Literature using and/or citing CarbonTracker

Please email us if you have suggested additions to this list.


Matching entries: 0
settings...
Aalto T, Hatakka J, Kouznetsov R and Stanislawska K (2015), "Background and anthropogenic influences on atmospheric CO2 concentrations measured at Pallas: comparison of two models for tracing air mass history", BOREAL ENVIRONMENT RESEARCH., APR 30, 2015. Vol. {20}({2}), pp. 213-226.
Abstract: The FLEXTRA and SILAM models were utilized in estimating the influence
regions (TR) for the measured CO2 concentration ([CO2]) at Pallas
together with tracers for anthropogenic emissions. The models produced
similar synoptic features and associated background [CO2] with marine
IR and elevated [CO2] with continental IR, but there were also
differences which affected the interpretation of measurements. The
background, i.e. marine boundary layer (MBL) signal, was compared to the
NOAA MBL reference. Both models performed well, with monthly mean
deviations from the reference usually inside 1 ppm. The FLEXTRA MBL
signal had some seasonality in the difference, however, only very few
cases were associated with anthropogenic emissions. We used [CO] and
fossil fuel [CO2] simulations by the TM5 (CarbonTracker CT2011oi)
model as emission tracers. The model and [CO] captured well the timing
of high [CO2] in measurements. The anthropogenic influence was more
pronounced in winter than in summer, and it had a large inter-annual
variation.
BibTeX:
@article{aalto15a,
  author = {Aalto, Tuula and Hatakka, Juha and Kouznetsov, Rostislav and Stanislawska, Karolina},
  title = {Background and anthropogenic influences on atmospheric CO2 concentrations measured at Pallas: comparison of two models for tracing air mass history},
  journal = {BOREAL ENVIRONMENT RESEARCH},
  year = {2015},
  volume = {20},
  number = {2},
  pages = {213--226}
}
Agol E, Jansen T, Lacy B, Robinson TD and Meadows V ({2015}), "THE CENTER OF LIGHT: SPECTROASTROMETRIC DETECTION OF EXOMOONS", ASTROPHYSICAL JOURNAL., OCT 10, {2015}. Vol. {812}({1})
Abstract: Direct imaging of extrasolar planets with future space-based
coronagraphic telescopes may provide a means of detecting companion
moons at wavelengths where the moon outshines the planet. We propose a
detection strategy based on the positional variation of the center of
light with wavelength, ``spectroastrometry.'' This new application of
this technique could be used to detect an exomoon, to determine the
exomoon's orbit and the mass of the host exoplanet, and to disentangle
the spectra of the planet and moon. We consider two model systems, for
which we discuss the requirements for detection of exomoons around
nearby stars. We simulate the characterization of an Earth-Moon analog
system with spectroastrometry, showing that the orbit, the planet mass,
and the spectra of both bodies can be recovered. To enable the detection
and characterization of exomoons we recommend that coronagraphic
telescopes should extend in wavelength coverage to 3 mu m, and should be
designed with spectroastrometric requirements in mind.
BibTeX:
@article{agol15a,
  author = {Agol, Eric and Jansen, Tiffany and Lacy, Brianna and Robinson, Tyler D. and Meadows, Victoria},
  title = {THE CENTER OF LIGHT: SPECTROASTROMETRIC DETECTION OF EXOMOONS},
  journal = {ASTROPHYSICAL JOURNAL},
  year = {2015},
  volume = {812},
  number = {1},
  doi = {10.1088/0004-637X/812/1/5}
}
Agusti-Panareda A, Massart S, Chevallier F, Balsamo G, Boussetta S, Dutra E and Beljaars A ({2016}), "A biogenic CO2 flux adjustment scheme for the mitigation of large-scale biases in global atmospheric CO2 analyses and forecasts", ATMOSPHERIC CHEMISTRY AND PHYSICS., AUG 18, {2016}. Vol. {16}({16}), pp. 10399-10418.
Abstract: Forecasting atmospheric CO2 daily at the global scale with a good
accuracy like it is done for the weather is a challenging task. However,
it is also one of the key areas of development to bridge the gaps
between weather, air quality and climate models. The challenge stems
from the fact that atmospheric CO2 is largely controlled by the CO2
fluxes at the surface, which are difficult to constrain with
observations. In particular, the biogenic fluxes simulated by land
surface models show skill in detecting synoptic and regional-scale
disturbances up to sub-seasonal time-scales, but they are subject to
large seasonal and annual budget errors at global scale, usually
requiring a posteriori adjustment. This paper presents a scheme to
diagnose and mitigate model errors associated with biogenic fluxes
within an atmospheric CO2 forecasting system. The scheme is an adaptive
scaling procedure referred to as a biogenic flux adjustment scheme
(BFAS), and it can be applied automatically in real time throughout the
forecast. The BFAS method generally improves the continental budget of
CO2 fluxes in the model by combining information from three sources: (1)
retrospective fluxes estimated by a global flux inversion system, (2)
land-use information, (3) simulated fluxes from the model. The method is
shown to produce enhanced skill in the daily CO2 10-day forecasts
without requiring continuous manual intervention. Therefore, it is
particularly suitable for near-real-time CO2 analysis and forecasting
systems.
BibTeX:
@article{agusti-panareda16a,
  author = {Agusti-Panareda, Anna and Massart, Sebastien and Chevallier, Frederic and Balsamo, Gianpaolo and Boussetta, Souhail and Dutra, Emanuel and Beljaars, Anton},
  title = {A biogenic CO2 flux adjustment scheme for the mitigation of large-scale biases in global atmospheric CO2 analyses and forecasts},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {16},
  pages = {10399--10418},
  doi = {10.5194/acp-16-10399-2016}
}
Ahlstrom A, Miller PA and Smith B ({2012}), "Too early to infer a global NPP decline since 2000", GEOPHYSICAL RESEARCH LETTERS., AUG 10, {2012}. Vol. {39}
Abstract: The global terrestrial carbon cycle plays a pivotal role in regulating
the atmospheric composition of greenhouse gases. It has recently been
suggested that the upward trend in net primary production (NPP) seen
during the 1980's and 90's has been replaced by a negative trend since
2000 induced by severe droughts mainly on the southern hemisphere. Here
we compare results from an individual-based global vegetation model to
satellite-based estimates of NPP and top-down reconstructions of net
biome production (NBP) based on inverse modelling of observed CO2
concentrations and CO2 growth rates. We find that simulated NBP exhibits
considerable covariation on a global scale with interannual fluctuations
in atmospheric CO2. Our simulations also suggest that droughts in the
southern hemisphere may have been a major driver of NPP variations
during the past decade. The results, however, do not support conjecture
that global terrestrial NPP has entered a period of drought-induced
decline. Citation: Ahlstrom, A., P. A. Miller, and B. Smith (2012), Too
early to infer a global NPP decline since 2000, Geophys. Res. Lett., 39,
L15403, doi:10.1029/2012GL052336.
BibTeX:
@article{ahlstrom12a,
  author = {Ahlstrom, Anders and Miller, Paul A. and Smith, Benjamin},
  title = {Too early to infer a global NPP decline since 2000},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2012},
  volume = {39},
  doi = {10.1029/2012GL052336}
}
Ahue WK (2010), "Regional carbon fluxes and boundary layer heights from the Airborne Carbon in the Mountains Experiment 2007". Thesis at: University of Wisconsin--Madison.
BibTeX:
@phdthesis{ahue10a,
  author = {Ahue, William KM},
  title = {Regional carbon fluxes and boundary layer heights from the Airborne Carbon in the Mountains Experiment 2007},
  school = {University of Wisconsin--Madison},
  year = {2010}
}
Alden CB, Miller JB and White JWC ({2010}), "Can bottom-up ocean CO2 fluxes be reconciled with atmospheric 13C observations?", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 369-388.
Abstract: The rare stable carbon isotope, 13C, has been used previously to
partition CO2 fluxes into land and ocean components. Net ocean and land
fluxes impose distinctive and predictable fractionation patterns upon
the stable isotope ratio, making it an excellent tool for distinguishing
between them. Historically, isotope constrained inverse methods for
calculating CO2 surface fluxes-the `double deconvolution'-have disagreed
with bottom-up ocean flux estimates. In this study, we use the double
deconvolution framework, but add, as a constraint, independent estimates
of time histories of ocean fluxes to the atmospheric observations of CO2
and 13CO(2). We calculate timeseries of net land flux, total
disequilibrium flux and terrestrial disequilibrium flux from 1991 to
2008 that are consistent with bottom-up net ocean fluxes. We investigate
possible drivers of interannual variability in terrestrial
disequilibrium flux, including terrestrial discrimination, and test the
sensitivity of our results to those mechanisms. We find that C-3 plant
discrimination and shifts in the global composition of C-3 and C-4
vegetation are likely drivers of interannual variability in terrestrial
disequilibrium flux, while contributions from heterotrophic respiration
and disturbance anomalies are also possible.
BibTeX:
@article{alden10a,
  author = {Alden, Caroline B. and Miller, John B. and White, James W. C.},
  title = {Can bottom-up ocean CO2 fluxes be reconciled with atmospheric 13C observations?},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {369--388},
  doi = {10.1111/j.1600-0889.2010.00481.x}
}
Alden CB, Miller JB, Gatti LV, Gloor MM, Guan K, Michalak AM, van der Laan-Luijkx IT, Touma D, Andrews A, Basso LS, Correia CSC, Domingues LG, Joiner J, Krol MC, Lyapustin AI, Peters W, Shiga YP, Thoning K, van der Velde IR, van Leeuwen TT, Yadav V and Diffenbaugh NS ({2016}), "Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange", GLOBAL CHANGE BIOLOGY., OCT, {2016}. Vol. {22}({10}), pp. 3427-3443.
Abstract: Understanding tropical rainforest carbon exchange and its response to
heat and drought is critical for quantifying the effects of climate
change on tropical ecosystems, including global climate-carbon
feedbacks. Of particular importance for the global carbon budget is net
biome exchange of CO2 with the atmosphere ( NBE), which represents
nonfire carbon fluxes into and out of biomass and soils. Subannual and
sub-Basin Amazon NBE estimates have relied heavily on process-based
biosphere models, despite lack of model agreement with plot-scale
observations. We present a new analysis of airborne measurements that
reveals monthly, regional-scale (similar to 1-8 x 10(6) km(2)) NBE
variations. We develop a regional atmospheric CO2 inversion that
provides the first analysis of geographic and temporal variability in
Amazon biosphere-atmosphere carbon exchange and that is minimally
influenced by biosphere model-based first guesses of seasonal and annual
mean fluxes. We find little evidence for a clear seasonal cycle in
Amazon NBE but do find NBE sensitivity to aberrations from long-term
mean climate. In particular, we observe increased NBE ( more carbon
emitted to the atmosphere) associated with heat and drought in 2010, and
correlations between wet season NBE and precipitation ( negative
correlation) and temperature ( positive correlation). In the eastern
Amazon, pulses of increased NBE persisted through 2011, suggesting
legacy effects of 2010 heat and drought. We also identify regional
differences in postdrought NBE that appear related to long-term water
availability. We examine satellite proxies and find evidence for higher
gross primary productivity ( GPP) during a pulse of increased carbon
uptake in 2011, and lower GPP during a period of increased NBE in the
2010 dry season drought, but links between GPP and NBE changes are not
conclusive. These results provide novel evidence of NBE sensitivity to
short-term temperature and moisture extremes in the Amazon, where
monthly and sub-Basin estimates have not been previously available.
BibTeX:
@article{alden16a,
  author = {Alden, Caroline B. and Miller, John B. and Gatti, Luciana V. and Gloor, Manuel M. and Guan, Kaiyu and Michalak, Anna M. and van der Laan-Luijkx, Ingrid T. and Touma, Danielle and Andrews, Arlyn and Basso, Luana S. and Correia, Caio S. C. and Domingues, Lucas G. and Joiner, Joanna and Krol, Maarten C. and Lyapustin, Alexei I. and Peters, Wouter and Shiga, Yoichi P. and Thoning, Kirk and van der Velde, Ivar R. and van Leeuwen, Thijs T. and Yadav, Vineet and Diffenbaugh, Noah S.},
  title = {Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2016},
  volume = {22},
  number = {10},
  pages = {3427--3443},
  doi = {10.1111/gcb.13305}
}
Alexandrov GA and Matsunaga T (2008), "Normative productivity of the global vegetation", Carbon balance and management. Vol. 3(1), pp. 8. Springer.
BibTeX:
@article{alexandrov08a,
  author = {Alexandrov, Georgii A and Matsunaga, Tsuneo},
  title = {Normative productivity of the global vegetation},
  journal = {Carbon balance and management},
  publisher = {Springer},
  year = {2008},
  volume = {3},
  number = {1},
  pages = {8}
}
Alexe M, Bergamaschi P, Segers A, Detmers R, Butz A, Hasekamp O, Guerlet S, Parker R, Boesch H, Frankenberg C, Scheepmaker RA, Dlugokencky E, Sweeney C, Wofsy SC and Kort EA ({2015}), "Inverse modelling of CH4 emissions for 2010-2011 using different satellite retrieval products from GOSAT and SCIAMACHY", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({1}), pp. 113-133.
Abstract: At the beginning of 2009 new space-borne observations of dry-air
column-averaged mole fractions of atmospheric methane (XCH4) became
available from the Thermal And Near infrared Sensor for carbon
Observations-Fourier Transform Spectrometer (TANSO-FTS) instrument on
board the Greenhouse Gases Observing SATellite (GOSAT). Until April 2012
concurrent methane (CH4) retrievals were provided by the SCanning
Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY)
instrument on board the ENVironmental SATellite (ENVISAT). The GOSAT and
SCIAMACHY XCH4 retrievals can be compared during the period of overlap.
We estimate monthly average CH4 emissions between January 2010 and
December 2011, using the TM5-4DVAR inverse modelling system. In addition
to satellite data, high-accuracy measurements from the Cooperative Air
Sampling Network of the National Oceanic and Atmospheric Administration
Earth System Research Laboratory (NOAA ESRL) are used, providing strong
constraints on the remote surface atmosphere. We discuss five inversion
scenarios that make use of different GOSAT and SCIAMACHY XCH4 retrieval
products, including two sets of GOSAT proxy retrievals processed
independently by the Netherlands Institute for Space Research
(SRON)/Karlsruhe Institute of Technology (KIT), and the University of
Leicester (UL), and the RemoTeC ``Full-Physics'' (FP) XCH4 retrievals
available from SRON/KIT. The GOSAT-based inversions show significant
reductions in the root mean square (rms) difference between retrieved
and modelled XCH4, and require much smaller bias corrections compared to
the inversion using SCIAMACHY retrievals, reflecting the higher
precision and relative accuracy of the GOSAT XCH4. Despite the large
differences between the GOSAT and SCIAMACHY retrievals, 2-year average
emission maps show overall good agreement among all satellite-based
inversions, with consistent flux adjustment patterns, particularly
across equatorial Africa and North America. Over North America, the
satellite inversions result in a significant redistribution of CH4
emissions from North-East to South-Central United States. This result is
consistent with recent independent studies suggesting a systematic
underestimation of CH4 emissions from North American fossil fuel sources
in bottom-up inventories, likely related to natural gas production
facilities. Furthermore, all four satellite inversions yield lower CH4
fluxes across the Congo basin compared to the NOAA-only scenario, but
higher emissions across tropical East Africa. The GOSAT and SCIAMACHY
inversions show similar performance when validated against independent
shipboard and aircraft observations, and XCH4 retrievals available from
the Total Carbon Column Observing Network (TCCON).
BibTeX:
@article{alexe15a,
  author = {Alexe, M. and Bergamaschi, P. and Segers, A. and Detmers, R. and Butz, A. and Hasekamp, O. and Guerlet, S. and Parker, R. and Boesch, H. and Frankenberg, C. and Scheepmaker, R. A. and Dlugokencky, E. and Sweeney, C. and Wofsy, S. C. and Kort, E. A.},
  title = {Inverse modelling of CH4 emissions for 2010-2011 using different satellite retrieval products from GOSAT and SCIAMACHY},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {1},
  pages = {113--133},
  doi = {10.5194/acp-15-113-2015}
}
Allen M, Erickson D, Kendall W, Fu J, Ott L and Pawson S ({2012}), "The influence of internal model variability in GEOS-5 on interhemispheric CO2 exchange", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 19, {2012}. Vol. {117}
Abstract: An ensemble of eight atmospheric CO2 simulations was completed employing
the National Aeronautics and Space Administration (NASA) Goddard Earth
Observation System, Version 5 (GEOS-5) for the years 2000-2001, each
with initial meteorological conditions corresponding to different days
in January 2000 to examine internal model variability. Globally, the
model runs show similar concentrations of CO2 for the two years, but in
regions of high CO2 concentrations due to fossil fuel emissions, large
differences among different model simulations appear. The phasing and
amplitude of the CO2 cycle at Northern Hemisphere locations in all of
the ensemble members is similar to that of surface observations. In
several southern hemisphere locations, however, some of the GEOS-5 model
CO2 cycles are out of phase by as much as four months, and large
variations occur between the ensemble members. This result indicates
that there is large sensitivity to transport in these regions. The
differences vary by latitude-the most extreme differences in the Tropics
and the least at the South Pole. Examples of these differences among the
ensemble members with regard to CO2 uptake and respiration of the
terrestrial biosphere and CO2 emissions due to fossil fuel emissions are
shown at Cape Grim, Tasmania. Integration-based flow analysis of the
atmospheric circulation in the model runs shows widely varying paths of
flow into the Tasmania region among the models including sources from
North America, South America, South Africa, South Asia and Indonesia.
These results suggest that interhemispheric transport can be strongly
influenced by internal model variability.
BibTeX:
@article{allen12a,
  author = {Allen, Melissa and Erickson, David and Kendall, Wesley and Fu, Joshua and Ott, Lesley and Pawson, Steven},
  title = {The influence of internal model variability in GEOS-5 on interhemispheric CO2 exchange},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2011JD017059}
}
Andres RJ, Boden TA, Breon FM, Ciais P, Davis S, Erickson D, Gregg JS, Jacobson A, Marland G, Miller J, Oda T, Olivier JGJ, Raupach MR, Rayner P and Treanton K ({2012}), "A synthesis of carbon dioxide emissions from fossil-fuel combustion", BIOGEOSCIENCES. Vol. {9}({5}), pp. 1845-1871.
Abstract: This synthesis discusses the emissions of carbon dioxide from
fossil-fuel combustion and cement production. While much is known about
these emissions, there is still much that is unknown about the details
surrounding these emissions. This synthesis explores our knowledge of
these emissions in terms of why there is concern about them; how they
are calculated; the major global efforts on inventorying them; their
global, regional, and national totals at different spatial and temporal
scales; how they are distributed on global grids (i.e., maps); how they
are transported in models; and the uncertainties associated with these
different aspects of the emissions. The magnitude of emissions from the
combustion of fossil fuels has been almost continuously increasing with
time since fossil fuels were first used by humans. Despite events in
some nations specifically designed to reduce emissions, or which have
had emissions reduction as a byproduct of other events, global total
emissions continue their general increase with time. Global total
fossil-fuel carbon dioxide emissions are known to within 10br> uncertainty (95% confidence interval). Uncertainty on individ-ual
national total fossil-fuel carbon dioxide emissions range from a few
percent to more than 50 %. This manuscript concludes that carbon
dioxide emissions from fossil-fuel combustion continue to increase with
time and that while much is known about the overall characteristics of
these emissions, much is still to be learned about the detailed
characteristics of these emissions.
BibTeX:
@article{andres12a,
  author = {Andres, R. J. and Boden, T. A. and Breon, F. -M. and Ciais, P. and Davis, S. and Erickson, D. and Gregg, J. S. and Jacobson, A. and Marland, G. and Miller, J. and Oda, T. and Olivier, J. G. J. and Raupach, M. R. and Rayner, P. and Treanton, K.},
  title = {A synthesis of carbon dioxide emissions from fossil-fuel combustion},
  journal = {BIOGEOSCIENCES},
  year = {2012},
  volume = {9},
  number = {5},
  pages = {1845--1871},
  doi = {10.5194/bg-9-1845-2012}
}
Andrews AE, Kofler JD, Trudeau ME, Williams JC, Neff DH, Masarie KA, Chao DY, Kitzis DR, Novelli PC, Zhao CL, Dlugokencky EJ, Lang PM, Crotwell MJ, Fischer ML, Parker MJ, Lee JT, Baumann DD, Desai AR, Stanier CO, De Wekker SFJ, Wolfe DE, Munger JW and Tans PP ({2014}), "CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({2}), pp. 647-687.
Abstract: A reliable and precise in situ CO2 and CO analysis system has been
developed and deployed at eight sites in the NOAA Earth System Research
Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network
uses very tall (> 300 m) television and radio transmitter towers that
provide a convenient platform for mid-boundary-layer trace-gas sampling.
Each analyzer has three sample inlets for profile sampling, and a
complete vertical profile is obtained every 15 min. The instrument suite
at one site has been augmented with a cavity ring-down spectrometer for
measuring CO2 and CH4. The long-term stability of the systems in the
field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5
ppb for CH4, as determined from repeated standard gas measurements. The
instrumentation is fully automated and includes sensors for measuring a
variety of status parameters, such as temperatures, pressures, and flow
rates, that are inputs for automated alerts and quality control
algorithms. Detailed and time-dependent uncertainty estimates have been
constructed for all of the gases, and the uncertainty framework could be
readily adapted to other species or analysis systems. The design
emphasizes use of off-theshelf parts and modularity to facilitate
network operations and ease of maintenance. The systems report
high-quality data with > 93% uptime. Recurrent problems and limitations
of the current system are discussed along with general recommendations
for high-accuracy trace-gas monitoring. The network is a key component
of the North American Carbon Program and a useful model for future
research-grade operational greenhouse gas monitoring efforts.
BibTeX:
@article{andrews14a,
  author = {Andrews, A. E. and Kofler, J. D. and Trudeau, M. E. and Williams, J. C. and Neff, D. H. and Masarie, K. A. and Chao, D. Y. and Kitzis, D. R. and Novelli, P. C. and Zhao, C. L. and Dlugokencky, E. J. and Lang, P. M. and Crotwell, M. J. and Fischer, M. L. and Parker, M. J. and Lee, J. T. and Baumann, D. D. and Desai, A. R. and Stanier, C. O. and De Wekker, S. F. J. and Wolfe, D. E. and Munger, J. W. and Tans, P. P.},
  title = {CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2014},
  volume = {7},
  number = {2},
  pages = {647--687},
  doi = {10.5194/amt-7-647-2014}
}
Babenhauserheide A, Basu S, Houweling S, Peters W and Butz A ({2015}), "Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({17}), pp. 9747-9763.
Abstract: Data assimilation systems allow for estimating surface fluxes of
greenhouse gases from atmospheric concentration measurements. Good
knowledge about fluxes is essential to understand how climate change
affects ecosystems and to characterize feedback mechanisms. Based on the
assimilation of more than 1 year of atmospheric in situ concentration
measurements, we compare the performance of two established data
assimilation models, CarbonTracker and TM5-4DVar (Transport Model 5 -
Four-Dimensional Variational model), for CO2 flux estimation.
CarbonTracker uses an ensemble Kalman filter method to optimize fluxes
on ecoregions. TM5-4DVar employs a 4-D variational method and optimizes
fluxes on a 6 degrees x 4 degrees longitude-latitude grid. Harmonizing
the input data allows for analyzing the strengths and weaknesses of the
two approaches by direct comparison of the modeled concentrations and
the estimated fluxes. We further assess the sensitivity of the two
approaches to the density of observations and operational parameters
such as the length of the assimilation time window.
Our results show that both models provide optimized CO2 concentration
fields of similar quality. In Antarctica CarbonTracker underestimates
the wintertime CO2 concentrations, since its 5-week assimilation window
does not allow for adjusting the distant surface fluxes in response to
the detected concentration mismatch. Flux estimates by CarbonTracker and
TM5-4DVar are consistent and robust for regions with good observation
coverage, regions with low observation coverage reveal significant
differences. In South America, the fluxes estimated by TM5-4DVar suffer
from limited representativeness of the few observations. For the North
American continent, mimicking the historical increase of the measurement
network density shows improving agreement between CarbonTracker and
TM5-4DVar flux estimates for increasing observation density.
BibTeX:
@article{babenhauserheide15a,
  author = {Babenhauserheide, A. and Basu, S. and Houweling, S. and Peters, W. and Butz, A.},
  title = {Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {17},
  pages = {9747--9763},
  doi = {10.5194/acp-15-9747-2015}
}
Badawy B, Polavarapu S, Jones DBA, Deng F, Neish M, Melton JR, Nassar R and Arora VK (2018), "Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model (v.107-glb)", GEOSCIENTIFIC MODEL DEVELOPMENT., FEB 20, 2018. Vol. 11(2), pp. 631-663.
Abstract: The Canadian Land Surface Scheme and the Canadian Terrestrial Ecosystem
Model (CLASS-CTEM) together form the land surface component in the
family of Canadian Earth system models (CanESMs). Here, CLASS-CTEM is
coupled to Environment and Climate Change Canada (ECCC)'s weather and
greenhouse gas forecast model (GEM-MACH-GHG) to consistently model
atmosphere-land exchange of CO2. The coupling between the land and the
atmospheric transport model ensures consistency between meteorological
forcing of CO2 fluxes and CO2 transport. The procedure used to spin up
carbon pools for CLASS-CTEM for multi-decadal simulations needed to be
significantly altered to deal with the limited availability of
consistent meteorological information from a constantly changing
operational environment in the GEM-MACH-GHG model. Despite the
limitations in the spin-up procedure, the simulated fluxes obtained by
driving the CLASS-CTEM model with meteorological forcing from
GEM-MACH-GHG were comparable to those obtained from CLASS-CTEM when it
is driven with standard meteorological forcing from the Climate Research
Unit (CRU) combined with reanalysis fields from the National Centers for
Environmental Prediction (NCEP) to form CRU-NCEP dataset. This is due to
the similarity of the two meteorological datasets in terms of
temperature and radiation. However, notable discrepancies in the
seasonal variation and spatial patterns of precipitation estimates,
especially in the tropics, were reflected in the estimated carbon
fluxes, as they significantly affected the mag-nitude of the vegetation
productivity and, to a lesser extent, the seasonal variations in carbon
fluxes. Nevertheless, the simulated fluxes based on the meteorological
forcing from the GEM-MACH-GHG model are consistent to some extent with
other estimates from bottom-up or top-down approaches. Indeed, when
simulated fluxes obtained by driving the CLASS-CTEM model with
meteorological data from the GEM-MACH-GHG model are used as prior
estimates for an atmospheric CO2 inversion analysis using the adjoint of
the GEOS-Chem model, the retrieved CO2 flux estimates are comparable to
those obtained from other systems in terms of the global budget and the
total flux estimates for the northern extratropical regions, which have
good observational coverage. In data-poor regions, as expected,
differences in the retrieved fluxes due to the prior fluxes become
apparent. Coupling CLASS-CTEM into the Environment Canada Carbon
Assimilation System (EC-CAS) is considered an important step toward
understanding how meteorological uncertainties affect both CO2 flux
estimates and modeled atmospheric transport. Ultimately, such an
approach will provide more direct feedback to the CLASS-CTEM developers
and thus help to improve the performance of CLASS-CTEM by identifying
the model limitations based on atmospheric constraints.
BibTeX:
@article{badawy18a,
  author = {Badawy, Bakr and Polavarapu, Saroja and Jones, Dylan B. A. and Deng, Feng and Neish, Michael and Melton, Joe R. and Nassar, Ray and Arora, Vivek K.},
  title = {Coupling the Canadian Terrestrial Ecosystem Model (CTEM v. 2.0) to Environment and Climate Change Canada's greenhouse gas forecast model (v.107-glb)},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2018},
  volume = {11},
  number = {2},
  pages = {631-663},
  doi = {10.5194/gmd-11-631-2018}
}
Baker IT, Denning AS and Stoeckli R ({2010}), "North American gross primary productivity: regional characterization and interannual variability", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 533-549.
Abstract: Seasonality and interannual variability in North American photosynthetic
activity reflect potential patterns of climate variability. We simulate
24 yr (1983-2006) and evaluate regional and seasonal contribution to
annual mean gross primary productivity (GPP) as well as its interannual
variability. The highest productivity occurs in Mexico, the southeast
United States and the Pacific Northwest. Annual variability is largest
in tropical Mexico, the desert Southwest and the Midwestern corridor. We
find that no single region or season consistently determines continental
annual GPP anomaly. GPP variability is dependent upon soil moisture
availability in low- and mid-latitudes, and temperature in the north.
Soil moisture is a better predictor than precipitation as it integrates
precipitation events temporally. The springtime anomaly is the most
frequent seasonal contributor to the annual GPP variability. No climate
mode (i.e. ENSO, NAM) can be associated with annual or seasonal
variability over the entire continent. We define a region extending from
the Northeast United States through the midwest and into the
southwestern United States and northern Mexico that explains a
significant fraction of the variability in springtime GPP. We cannot
correlate this region to a single mechanism (i.e. temperature,
precipitation or soil moisture) or mode of climate variability.
BibTeX:
@article{baker10a,
  author = {Baker, Ian T. and Denning, A. Scott and Stoeckli, Reto},
  title = {North American gross primary productivity: regional characterization and interannual variability},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {533--549},
  doi = {10.1111/j.1600-0889.2010.00492.x}
}
Ballantyne AP, Miller JB and Tans PP ({2010}), "Apparent seasonal cycle in isotopic discrimination of carbon in the atmosphere and biosphere due to vapor pressure deficit", GLOBAL BIOGEOCHEMICAL CYCLES., SEP 10, {2010}. Vol. {24}
Abstract: We explore seasonal variability in isotopic fractionation by analyzing
observational data from the atmosphere and the biosphere, as well as
simulated data from a global model. Using simulated values of
atmospheric CO2 and its carbon isotopic composition, we evaluated
different methods for specifying background concentrations when
calculating the isotopic signature of source CO2 (delta(s)) to the
atmosphere. Based on this evaluation, we determined that free
troposphere measurements should be used when available as a background
reference when calculating delta(s) from boundary layer observations. We
then estimate the seasonal distribution of delta(s) from monthly
climatologies derived from several atmospheric sampling sites. This
approach yields significant seasonal variations in delta(s) with more
enriched values during the summer months that exceed the uncertainty of
delta(s) estimated for any given month. Intra-annual measurements of
delta C-13 in the cellulose of Pinus taeda growing in the southeastern
U.S. also reveal seasonal isotopic variations that are consistent in
phase but not necessarily amplitude with atmospherically derived
estimates of delta(s). Coherent seasonal patterns in delta(s) inferred
from the atmosphere and observed in the biosphere were not consistent
with the seasonal isotopic discrimination simulated by a commonly used
biosphere model. However, delta(s) seasonality consistent with
observations from the atmosphere and biosphere was retrieved with a
revised biosphere model when stomatal conductance, and thus isotopic
discrimination, was allowed to vary in response to vapor pressure
deficit rather than relative humidity. Therefore, in regions where vapor
pressure deficit and relative humidity are positively covariant over the
growth season, such as the sub-tropics, different stomatal conductance
models may yield very different estimates of CO2 and H2O exchange
between the biosphere and atmosphere.
BibTeX:
@article{ballantyne10a,
  author = {Ballantyne, A. P. and Miller, J. B. and Tans, P. P.},
  title = {Apparent seasonal cycle in isotopic discrimination of carbon in the atmosphere and biosphere due to vapor pressure deficit},
  journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
  year = {2010},
  volume = {24},
  doi = {10.1029/2009GB003623}
}
Barichivich J, Briffa KR, Osborn TJ, Melvin TM and Caesar J ({2012}), "Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere", GLOBAL BIOGEOCHEMICAL CYCLES., DEC 6, {2012}. Vol. {26}
Abstract: Gridded daily temperature from 1950 to 2011 and atmospheric CO2
concentration data from high-latitude observing stations and the
CarbonTracker assimilation system are used to examine recent
spatiotemporal variability of the thermal growing season and its
relationship with seasonal biospheric carbon uptake and release in the
Northern Hemisphere. The thermal growing season has lengthened
substantially since 1950 but most of the lengthening has occurred during
the last three decades (2.9 days decade(-1), p < 0.01 for 1980-2011),
with stronger rates of extension in Eurasia (4.0 days decade(-1), p <
0.01) than in North America (1.2 days decade(-1), p > 0.05). Unlike most
previous studies, which had more limited data coverage over the past
decade, we find that strong autumn warming of about 1 degrees C during
the second half of the 2000s has led to a significant shift toward later
termination of the thermal growing season, resulting in the longest
potential growing seasons since 1950. On average, the thermal growing
season has extended symmetrically by about a week during this period,
starting some 4.0 days earlier and ending about 4.3 days later. The
earlier start of the thermal growing season is associated with earlier
onset of the biospheric carbon uptake period at high northern latitudes.
In contrast, later termination of the growing season is associated with
earlier termination of biospheric carbon uptake, but this relationship
appears to have decoupled since the beginning of the period of strong
autumn warming during the second half of the 2000s. Therefore, owing to
these contrasting biospheric responses at the margins of the growing
season, the current extension in the thermal growing season length has
not led to a concomitant extension of the period of biospheric carbon
uptake.
BibTeX:
@article{barichivich12a,
  author = {Barichivich, J. and Briffa, K. R. and Osborn, T. J. and Melvin, T. M. and Caesar, J.},
  title = {Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere},
  journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
  year = {2012},
  volume = {26},
  doi = {10.1029/2012GB004312}
}
(2018), "Detection and attribution of carbon cycle processes from atmospheric O2 and CO2 measurements at Halley Research Station, Antarctica and Weybourne Atmospheric Observatory, U.K." UNIVERSITY OF EAST ANGLIA, U.K..
BibTeX:
@phdthesis{barningham18a,,
  title = {Detection and attribution of carbon cycle processes from atmospheric O2 and CO2 measurements at Halley Research Station, Antarctica and Weybourne Atmospheric Observatory, U.K.},
  publisher = {UNIVERSITY OF EAST ANGLIA, U.K.},
  year = {2018}
}
Barthlott S, Schneider M, Hase F, Wiegele A, Christner E, Gonzalez Y, Blumenstock T, Dohe S, Garcia OE, Sepulveda E, Strong K, Mendonca J, Weaver D, Palm M, Deutscher NM, Warneke T, Notholt J, Lejeune B, Mahieu E, Jones N, Griffith DWT, Velazco VA, Smale D, Robinson J, Kivi R, Heikkinen P and Raffalski U ({2015}), "Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({3}), pp. 1555-1573.
Abstract: Within the NDACC (Network for the Detection of Atmospheric Composition
Change), more than 20 FTIR (Fourier-transform infrared) spectrometers,
spread worldwide, provide long-term data records of many atmospheric
trace gases. We present a method that uses measured and modelled XCO2
for assessing the consistency of these NDACC data records. Our XCO2
retrieval setup is kept simple so that it can easily be adopted for any
NDACC/FTIR-like measurement made since the late 1950s. By a comparison
to coincident TCCON (Total Carbon Column Observing Network)
measurements, we empirically demonstrate the useful quality of this
suggested NDACC XCO2 product (empirically obtained scatter between TCCON
and NDACC is about 4 parts per thousand for daily mean as well as
monthly mean comparisons, and the bias is 25 parts per thousand). Our
XCO2 model is a simple regression model fitted to CarbonTracker results
and the Mauna Loa CO2 in situ records. A comparison to TCCON data
suggests an uncertainty of the model for monthly mean data of below 3
parts per thousand. We apply the method to the NDACC/FTIR spectra that
are used within the project MUSICA (multi-platform remote sensing of
isotopologues for investigating the cycle of atmospheric water) and
demonstrate that there is a good consistency for these globally
representative set of spectra measured since 1996: the scatter between
the modelled and measured XCO2 on a yearly time scale is only 3 parts
per thousand.
BibTeX:
@article{barthlott15a,
  author = {Barthlott, S. and Schneider, M. and Hase, F. and Wiegele, A. and Christner, E. and Gonzalez, Y. and Blumenstock, T. and Dohe, S. and Garcia, O. E. and Sepulveda, E. and Strong, K. and Mendonca, J. and Weaver, D. and Palm, M. and Deutscher, N. M. and Warneke, T. and Notholt, J. and Lejeune, B. and Mahieu, E. and Jones, N. and Griffith, D. W. T. and Velazco, V. A. and Smale, D. and Robinson, J. and Kivi, R. and Heikkinen, P. and Raffalski, U.},
  title = {Using XCO2 retrievals for assessing the long-term consistency of NDACC/FTIR data sets},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {3},
  pages = {1555--1573},
  doi = {10.5194/amt-8-1555-2015}
}
Basu S, Houweling S, Peters W, Sweeney C, Machida T, Maksyutov S, Patra PK, Saito R, Chevallier F, Niwa Y, Matsueda H and Sawa Y ({2011}), "The seasonal cycle amplitude of total column CO2: Factors behind the model-observation mismatch", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 15, {2011}. Vol. {116}
Abstract: CO2 surface fluxes that are statistically consistent with surface layer
measurements of CO2, when propagated forward in time by atmospheric
transport models, underestimate the seasonal cycle amplitude of total
column CO2 in the northern temperate latitudes by 1-2 ppm. In this paper
we verify the systematic nature of this underestimation at a number of
Total Carbon Column Observation Network (TCCON) stations by comparing
their measurements with a number of transport models. In particular, at
Park Falls, Wisconsin (United States), we estimate this mismatch to be
1.4 ppm and try to attribute portions of this mismatch to different
factors affecting the total column. We find that errors due to (1) the
averaging kernel and prior profile used in forward models, (2) water
vapor in the model atmosphere, (3) incorrect vertical transport by
transport models in the free troposphere, (4) incorrect aging of air in
transport models in the stratosphere, and (5) air mass dependence in
TCCON data can explain up to 1 ppm of this mismatch. The remaining 0.4
ppm mismatch is at the edge of the <= 0.4 ppm accuracy requirement on
satellite measurements to improve on our current estimate of surface
fluxes. Uncertainties in the biosphere fluxes driving the transport
models could explain a part of the remaining 0.4 ppm mismatch, implying
that with corrections to the factors behind the accounted-for 1 ppm
underestimation, present inverse modeling frameworks could effectively
assimilate satellite CO2 measurements.
BibTeX:
@article{basu11a,
  author = {Basu, Sourish and Houweling, Sander and Peters, Wouter and Sweeney, Colm and Machida, Toshinobu and Maksyutov, Shamil and Patra, Prabir K. and Saito, Ryu and Chevallier, Frederic and Niwa, Yosuke and Matsueda, Hidekazu and Sawa, Yousuke},
  title = {The seasonal cycle amplitude of total column CO2: Factors behind the model-observation mismatch},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2011JD016124}
}
Basu S, Guerlet S, Butz A, Houweling S, Hasekamp O, Aben I, Krummel P, Steele P, Langenfelds R, Torn M, Biraud S, Stephens B, Andrews A and Worthy D ({2013}), "Global CO2 fluxes estimated from GOSAT retrievals of total column CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({17}), pp. 8695-8717.
Abstract: We present one of the first estimates of the global distribution of CO2
surface fluxes using total column CO2 measurements retrieved by the
SRON-KIT RemoTeC algorithm from the Greenhouse gases Observing SATellite
(GOSAT). We derive optimized fluxes from June 2009 to December 2010. We
estimate fluxes from surface CO2 measurements to use as baselines for
comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we
can reproduce the observed CO2 time series at surface and TC-CON sites
in the tropics and the northern extra-tropics. In contrast, in the
southern extra-tropics GOSAT X-CO2 leads to enhanced seasonal cycle
amplitudes compared to independent measurements, and we identify it as
the result of a land-sea bias in our GOSAT X-CO2 retrievals. A bias
correction in the form of a global offset between GOSAT land and sea
pixels in a joint inversion of satellite and surface measurements of CO2
yields plausible global flux estimates which are more tightly
constrained than in an inversion using surface CO2 data alone. We show
that assimilating the biascorrected GOSAT data on top of surface CO2
data (a) reduces the estimated global land sink of CO2, and (b) shifts
the terrestrial net uptake of carbon from the tropics to the
extratropics. It is concluded that while GOSAT total column CO2 provide
useful constraints for source-sink inversions, small spatiotemporal
biases -beyond what can be detected using current validation techniques
- have serious consequences for optimized fluxes, even aggregated over
continental scales.
BibTeX:
@article{basu13a,
  author = {Basu, S. and Guerlet, S. and Butz, A. and Houweling, S. and Hasekamp, O. and Aben, I. and Krummel, P. and Steele, P. and Langenfelds, R. and Torn, M. and Biraud, S. and Stephens, B. and Andrews, A. and Worthy, D.},
  title = {Global CO2 fluxes estimated from GOSAT retrievals of total column CO2},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {17},
  pages = {8695--8717},
  doi = {10.5194/acp-13-8695-2013}
}
Basu S, Miller JB and Lehman S ({2016}), "Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and (CO2)-C-14 measurements: Observation System Simulations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({9}), pp. 5665-5683.
Abstract: National annual total CO2 emissions from combustion of fossil fuels are
likely known to within 5-10aEuro-% for most developed countries.
However, uncertainties are inevitably larger (by unknown amounts) for
emission estimates at regional and monthly scales, or for developing
countries. Given recent international efforts to establish emission
reduction targets, independent determination and verification of
regional and national scale fossil fuel CO2 emissions are likely to
become increasingly important. Here, we take advantage of the fact that
precise measurements of C-14 in CO2 provide a largely unbiased tracer
for recently added fossil-fuel-derived CO2 in the atmosphere and present
an atmospheric inversion technique to jointly assimilate observations of
CO2 and (CO2)-C-14 in order to simultaneously estimate fossil fuel
emissions and biospheric exchange fluxes of CO2. Using this method in a
set of Observation System Simulation Experiments (OSSEs), we show that
given the coverage of (CO2)-C-14 measurements available in 2010 (969
over North America, 1063 globally), we can recover the US national total
fossil fuel emission to better than 1aEuro-% for the year and to within
5aEuro-% for most months. Increasing the number of (CO2)-C-14
observations to similar to 5000 per year over North America, as recently
recommended by the National Academy of Science (NAS) (Pacala et al.,
2010), we recover monthly emissions to within 5aEuro-% for all months
for the US as a whole and also for smaller, highly emissive regions over
which the specified data coverage is relatively dense, such as for the
New England states or the NY-NJ-PA tri-state area. This result suggests
that, given continued improvement in state-of-the art transport models,
a measurement program similar in scale to that recommended by the NAS
can provide for independent verification of bottom-up inventories of
fossil fuel CO2 at the regional and national scale. In addition, we show
that the dual tracer inversion framework can detect and minimize biases
in estimates of the biospheric flux that would otherwise arise in a
traditional CO2-only inversion when prescribing fixed but inaccurate
fossil fuel fluxes.
BibTeX:
@article{basu16a,
  author = {Basu, Sourish and Miller, John Bharat and Lehman, Scott},
  title = {Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and (CO2)-C-14 measurements: Observation System Simulations},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {9},
  pages = {5665--5683},
  doi = {10.5194/acp-16-5665-2016}
}
Belikov DA, Bril A, Maksyutov S, Oshchepkov S, Saeki T, Takagi H, Yoshida Y, Ganshin A, Zhuravlev R, Aoki S and Yokota T ({2014}), "Column-averaged CO2 concentrations in the subarctic from GOSAT retrievals and NIES transport model simulations", POLAR SCIENCE., JUN, {2014}. Vol. {8}({2, SI}), pp. 129-145.
Abstract: The distribution of atmospheric carbon dioxide (CO2) in the subarctic
was investigated using the National Institute for Environmental Studies
(NIBS) three-dimensional transport model (TM) and retrievals from the
Greenhouse gases Observing SATellite (GOSAT). Column-averaged dry air
mole fractions of subarctic atmospheric CO2 (XCO2) from the NIES TM for
four flux combinations were analyzed. Two flux datasets were optimized
using only surface observations and two others were optimized using both
surface and GOSAT Level 2 data. Two inverse modeling approaches using
GOSAT data were compared. In the basic approach adopted in the GOSAT
Level 4 product, the GOSAT observations are aggregated into monthly
means over 5 degrees x 5 degrees grids. In the alternative method, the
model observation misfit is estimated for each observation separately.
The XCO2 values simulated with optimized fluxes were validated against
Total Carbon Column Observing Network (TCCON) ground-based
high-resolution Fourier Transform Spectrometer (FTS) measurements.
Optimized fluxes were applied to study XCO2 seasonal variability over
the period 2009-2010 in the Arctic and subarctic regions. The impact on
CO2 levels of emissions from enhancement of biospheric respiration
induced by the high temperature and strong wildfires occurring in the
summer of 2010 was analyzed. Use of GOSAT data has a substantial impact
on estimates of the level of CO2 interanual variability. (C) 2014
Elsevier B.V. and NIPR. All rights reserved.
BibTeX:
@article{belikov14a,
  author = {Belikov, D. A. and Bril, A. and Maksyutov, S. and Oshchepkov, S. and Saeki, T. and Takagi, H. and Yoshida, Y. and Ganshin, A. and Zhuravlev, R. and Aoki, S. and Yokota, T.},
  title = {Column-averaged CO2 concentrations in the subarctic from GOSAT retrievals and NIES transport model simulations},
  journal = {POLAR SCIENCE},
  year = {2014},
  volume = {8},
  number = {2, SI},
  pages = {129--145},
  doi = {10.1016/j.polar.2014.02.002}
}
Belikov DA, Maksyutov S, Yaremchuk A, Ganshin A, Kaminski T, Blessing S, Sasakawa M, Gomez-Pelaez AJ and Starchenko A ({2016}), "Adjoint of the global Eulerian-Lagrangian coupled atmospheric transport model (A-GELCA v1.0): development and validation", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {9}({2}), pp. 749-764.
Abstract: We present the development of the Adjoint of the Global
Eulerian-Lagrangian Coupled Atmospheric (A-GELCA) model that consists of
the National Institute for Environmental Studies (NIES) model as an
Eulerian three-dimensional transport model (TM), and FLEXPART (FLEXible
PARTicle dispersion model) as the Lagrangian Particle Dispersion Model
(LPDM). The forward tangent linear and adjoint components of the
Eulerian model were constructed directly from the original NIES TM code
using an automatic differentiation tool known as TAF (Transformation of
Algorithms in Fortran; http://www.FastOpt.com), with additional manual
pre- and post-processing aimed at improving transparency and clarity of
the code and optimizing the performance of the computing, including MPI
(Message Passing Interface). The Lagrangian component did not require
any code modification, as LPDMs are self-adjoint and track a significant
number of particles backward in time in order to calculate the
sensitivity of the observations to the neighboring emission areas. The
constructed Eulerian adjoint was coupled with the Lagrangian component
at a time boundary in the global domain. The simulations presented in
this work were performed using the A-GELCA model in forward and adjoint
modes. The forward simulation shows that the coupled model improves
reproduction of the seasonal cycle and short-term variability of CO2.
Mean bias and standard deviation for five of the six Siberian sites
considered decrease roughly by 1 ppm when using the coupled model. The
adjoint of the Eulerian model was shown, through several numerical
tests, to be very accurate (within machine epsilon with mismatch around
to +/- 6 e(-14)) compared to direct forward sensitivity calculations.
The developed adjoint of the coupled model combines the flux
conservation and stability of an Eulerian discrete adjoint formulation
with the flexibility, accuracy, and high resolution of a Lagrangian
backward trajectory formulation. A-GELCA will be incorporated into a
variational inversion system designed to optimize surface fluxes of
greenhouse gases.
BibTeX:
@article{belikov16a,
  author = {Belikov, Dmitry A. and Maksyutov, Shamil and Yaremchuk, Alexey and Ganshin, Alexander and Kaminski, Thomas and Blessing, Simon and Sasakawa, Motoki and Gomez-Pelaez, Angel J. and Starchenko, Alexander},
  title = {Adjoint of the global Eulerian-Lagrangian coupled atmospheric transport model (A-GELCA v1.0): development and validation},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2016},
  volume = {9},
  number = {2},
  pages = {749--764},
  doi = {10.5194/gmd-9-749-2016}
}
Berberoglu H, Gomez PS and Pilon L ({2009}), "Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO2 fixation and biofuel production", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2009}. Vol. {110}({17}), pp. 1879-1893.
Abstract: This paper reports experimental measurements of the radiation
characteristics of green algae Used for carbon dioxide fixation via
photosynthesis. The generated biomass can be used to produce not only
biofuels but also feed for animal and food supplements for human
consumptions. Particular attention was paid to three widely used species
namely Botryococcus braunii, Chlorella sp., and Chlorococcum littorale.
Their extinction and absorption coefficients were obtained from
normal-normal and normal-hemispherical transmittance measurements over
the spectral range from 400 to 800 nm. Moreover, a polar nephelometer
was used to measure the scattering phase function of the microorganisms
at 632.8 nm. It was observed that for all strains, scattering dominates
over absorption. The magnitudes of the extinction and scattering
cross-section are functions of the size, shape, and chlorophyll content
of each strain in a nontrivial manner. Absorption peaks at 435,475, and
676 nm corresponding to chlorophyll a and chlorophyll b. The results can
be used for scaling and optimization of CO2 fixation in ponds or
photobioreactors as well as in the development of controlled ecological
life support systems. (C) 2009 Elsevier Ltd. All rights reserved.
BibTeX:
@article{berberoglu09a,
  author = {Berberoglu, Halil and Gomez, Pedro S. and Pilon, Laurent},
  title = {Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO2 fixation and biofuel production},
  journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
  year = {2009},
  volume = {110},
  number = {17},
  pages = {1879--1893},
  doi = {10.1016/j.jqsrt.2009.04.005}
}
Bergamaschi P, Frankenberg C, Meirink JF, Krol M, Villani MG, Houweling S, Dentener F, Dlugokencky EJ, Miller JB, Gatti LV, Engel A and Levin I ({2009}), "Inverse modeling of global and regional CH4 emissions using SCIAMACHY satellite retrievals", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 17, {2009}. Vol. {114}
Abstract: Methane retrievals from the Scanning Imaging Absorption Spectrometer for
Atmospheric Chartography (SCIAMACHY) instrument onboard ENVISAT provide
important information on atmospheric CH4 sources, particularly in
tropical regions which are poorly monitored by in situ surface
observations. Recently, Frankenberg et al. (2008a, 2008b) reported a
major revision of SCIAMACHY retrievals due to an update of spectroscopic
parameters of water vapor and CH4. Here, we analyze the impact of this
revision on global and regional CH4 emissions estimates in 2004, using
the TM5-4DVAR inverse modeling system. Inversions based on the revised
SCIAMACHY retrievals yield similar to 20% lower tropical emissions
compared to the previous retrievals. The new retrievals improve
significantly the consistency between observed and assimilated column
average mixing ratios and the agreement with independent validation
data. Furthermore, the considerable latitudinal and seasonal bias
correction of the previous SCIAMACHY retrievals, derived in the
TM5-4DVAR system by simultaneously assimilating high-accuracy surface
measurements, is reduced by a factor of similar to 3. The inversions
result in significant changes in the spatial patterns of emissions and
their seasonality compared to the bottom-up inventories. Sensitivity
tests were done to analyze the robustness of retrieved emissions,
revealing some dependence on the applied a priori emission inventories
and OH fields. Furthermore, we performed a detailed validation of
simulated CH4 mixing ratios using NOAA ship and aircraft profile
samples, as well as stratospheric balloon samples, showing overall good
agreement. We use the new SCIAMACHY retrievals for a regional analysis
of CH4 emissions from South America, Africa, and Asia, exploiting the
zooming capability of the TM5 model. This allows a more detailed
analysis of spatial emission patterns and better comparison with
aircraft profiles and independent regional emission estimates available
for South America. Large CH4 emissions are attributed to various wetland
regions in tropical South America and Africa, seasonally varying and
opposite in phase with CH4 emissions from biomass burning. India, China
and South East Asia are characterized by pronounced emissions from rice
paddies peaking in the third quarter of the year, in addition to further
anthropogenic emissions throughout the year.
BibTeX:
@article{bergamaschi09a,
  author = {Bergamaschi, Peter and Frankenberg, Christian and Meirink, Jan Fokke and Krol, Maarten and Villani, M. Gabriella and Houweling, Sander and Dentener, Frank and Dlugokencky, Edward J. and Miller, John B. and Gatti, Luciana V. and Engel, Andreas and Levin, Ingeborg},
  title = {Inverse modeling of global and regional CH4 emissions using SCIAMACHY satellite retrievals},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2009},
  volume = {114},
  doi = {10.1029/2009JD012287}
}
Bergamaschi P, Houweling S, Segers A, Krol M, Frankenberg C, Scheepmaker RA, Dlugokencky E, Wofsy SC, Kort EA, Sweeney C, Schuck T, Brenninkmeijer C, Chen H, Beck V and Gerbig C ({2013}), "Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUL 16, {2013}. Vol. {118}({13}), pp. 7350-7369.
Abstract: The causes of renewed growth in the atmospheric CH4 burden since 2007
are still poorly understood and subject of intensive scientific
discussion. We present a reanalysis of global CH4 emissions during the
2000s, based on the TM5-4DVAR inverse modeling system. The model is
optimized using high-accuracy surface observations from NOAA ESRL's
global air sampling network for 2000-2010 combined with retrievals of
column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT
(starting 2003). Using climatological OH fields, derived global total
emissions for 2007-2010 are 16-20 Tg CH4/yr higher compared to
2003-2005. Most of the inferred emission increase was located in the
tropics (9-14 Tg CH4/yr) and mid- latitudes of the northern hemisphere
(6-8 Tg CH4/yr), while no significant trend was derived for Arctic
latitudes. The atmospheric increase can be attributed mainly to
increased anthropogenic emissions, but the derived trend is
significantly smaller than estimated in the EDGARv4.2 emission
inventory. Superimposed on the increasing trend in anthropogenic CH4
emissions are significant inter-annual variations (IAV) of emissions
from wetlands (up to +/- 10 Tg CH4/yr), and biomass burning (up to +/- 7
Tg CH4/yr). Sensitivity experiments, which investigated the impact of
the SCIAMACHY observations (versus inversions using only surface
observations), of the OH fields used, and of a priori emission
inventories, resulted in differences in the detailed latitudinal
attribution of CH4 emissions, but the IAV and trends aggregated over
larger latitude bands were reasonably robust. All sensitivity
experiments show similar performance against independent shipboard and
airborne observations used for validation, except over Amazonia where
satellite retrievals improved agreement with observations in the free
troposphere.
BibTeX:
@article{bergamaschi13a,
  author = {Bergamaschi, P. and Houweling, S. and Segers, A. and Krol, M. and Frankenberg, C. and Scheepmaker, R. A. and Dlugokencky, E. and Wofsy, S. C. and Kort, E. A. and Sweeney, C. and Schuck, T. and Brenninkmeijer, C. and Chen, H. and Beck, V. and Gerbig, C.},
  title = {Atmospheric CH4 in the first decade of the 21st century: Inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2013},
  volume = {118},
  number = {13},
  pages = {7350--7369},
  doi = {10.1002/jgrd.50480}
}
Berry JA ({2012}), "There Ought to Be an Equation for That", Annual Review of Plant Biology., In ANNUAL REVIEW OF PLANT BIOLOGY, VOL 63. Vol. {63}(1), pp. 1-17.
Abstract: An overriding interest in photosynthesis has propelled my wanderings
from chemist to biochemist to plant physiologist and on to global
topics. Equations and models have been organizing principles along the
way. This fascination started as a reaction to difficulties with written
communication, but it has proven to be quite useful in moving across
different levels of organization. I conclude with some discussion of the
importance of Earth system models for understanding and predicting how
human activities may influence the climate, environment, and biota in
the future, and some ideas about how disciplinary science might make
larger contributions to this interdisciplinary problem.
BibTeX:
@article{berry12a,
  author = {Berry, Joseph A.},
  editor = {Merchant, SS},
  title = {There Ought to Be an Equation for That},
  booktitle = {ANNUAL REVIEW OF PLANT BIOLOGY, VOL 63},
  journal = {Annual Review of Plant Biology},
  year = {2012},
  volume = {63},
  number = {1},
  pages = {1--17},
  doi = {10.1146/annurev-arplant-042811-105547}
}
Biavati G, Feist DG, Gerbig C and Kretschmer R ({2015}), "Error estimation for localized signal properties: application to atmospheric mixing height retrievals", Atmospheric Measurement Techniques. Vol. {8}({10}), pp. 4215-4230.
Abstract: The mixing height is a key parameter for many applications that relate
surface-atmosphere exchange fluxes to atmospheric mixing ratios, e.g.,
in atmospheric transport modeling of pollutants. The mixing height can
be estimated with various methods: profile measurements from radiosondes
as well as remote sensing (e.g., optical backscatter measurements). For
quantitative applications, it is important to estimate not only the
mixing height itself but also the uncertainty associated with this
estimate. However, classical error propagation typically fails on mixing
height estimates that use thresholds in vertical profiles of some
measured or measurement-derived quantity. Therefore, we propose a method
to estimate the uncertainty of an estimation of the mixing height. The
uncertainty we calculate is related not to the physics of the boundary
layer (e.g., entrainment zone thickness) but to the quality of the
analyzed signals. The method relies on the concept of statistical
confidence and on the knowledge of the measurement errors. It can also
be applied to problems outside atmospheric mixing height retrievals
where properties have to be assigned to a specific position, e.g., the
location of a local extreme.
BibTeX:
@article{biavati15a,
  author = {Biavati, G. and Feist, D. G. and Gerbig, C. and Kretschmer, R.},
  title = {Error estimation for localized signal properties: application to atmospheric mixing height retrievals},
  journal = {Atmospheric Measurement Techniques},
  year = {2015},
  volume = {8},
  number = {10},
  pages = {4215--4230},
  doi = {10.5194/amt-8-4215-2015}
}
Biraud SC, Torn MS, Smith JR, Sweeney C, Riley WJ and Tans PP ({2013}), "A multi-year record of airborne CO2 observations in the US Southern Great Plains", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({3}), pp. 751-763.
Abstract: We report on 10 yr of airborne measurements of atmospheric CO2 mole
fraction from continuous and flask systems, collected between 2002 and
2012 over the Atmospheric Radiation Measurement Program Climate Research
Facility in the US Southern Great Plains (SGP). These observations were
designed to quantify trends and variability in atmospheric mole fraction
of CO2 and other greenhouse gases with the precision and accuracy needed
to evaluate ground-based and satellite-based column CO2 estimates, test
forward and inverse models, and help with the interpretation of
ground-based CO2 mole-fraction measurements. During flights, we measured
CO2 and meteorological data continuously and collected flasks for a rich
suite of additional gases: CO2, CO, CH4, N2O, (CO2)-C-13, carbonyl
sulfide (COS), and trace hydrocarbon species. These measurements were
collected approximately twice per week by small aircraft (Cessna 172
initially, then Cessna 206) on a series of horizontal legs ranging in
altitude from 460 m to 5500 m a.m.s.l. Since the beginning of the
program, more than 400 continuous CO2 vertical profiles have been
collected (2007-2012), along with about 330 profiles from NOAA/ESRL
12-flask (2006-2012) and 284 from NOAA/ESRL 2-flask (2002-2006) packages
for carbon cycle gases and isotopes. Averaged over the entire record,
there were no systematic differences between the continuous and flask
CO2 observations when they were sampling the same air, i.e., over the
one-minute flask-sampling time. Using multiple technologies (a flask
sampler and two continuous analyzers), we documented a mean difference
of < 0.2 ppm between instruments. However, flask data were not
equivalent in all regards; horizontal variability in CO2 mole fraction
within the 5-10 min legs sometimes resulted in significant differences
between flask and continuous measurement values for those legs, and the
information contained in fine-scale variability about atmospheric
transport was not captured by flask-based observations. The CO2 mole
fraction trend at 3000 m a.m.s.l. was 1.91 ppm yr(-1) between 2008 and
2010, very close to the concurrent trend at Mauna Loa of 1.95 ppm
yr(-1). The seasonal amplitude of CO2 mole fraction in the free
troposphere (FT) was half that in the planetary boundary layer (PBL)
(similar to 15 ppm vs. similar to 30 ppm) and twice that at Mauna Loa
(approximately 8 ppm). The CO2 horizontal variability was up to 10 ppm
in the PBL and less than 1 ppm at the top of the vertical profiles in
the FT.
BibTeX:
@article{biraud13a,
  author = {Biraud, S. C. and Torn, M. S. and Smith, J. R. and Sweeney, C. and Riley, W. J. and Tans, P. P.},
  title = {A multi-year record of airborne CO2 observations in the US Southern Great Plains},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2013},
  volume = {6},
  number = {3},
  pages = {751--763},
  doi = {10.5194/amt-6-751-2013}
}
Bodesheim P, Jung M, Gans F, Mahecha MD and Reichstein M (2018), "Upscaled diurnal cycles of land-atmosphere fluxes: a new global half-hourly data product", Earth System Science Data., JUL 20, 2018. Vol. 10(3), pp. 1327-1365.
Abstract: Interactions between the biosphere and the atmosphere can be well
characterized by fluxes between the two. In particular, carbon and
energy fluxes play a major role in understanding biogeochemical
processes on an ecosystem level or global scale. However, the fluxes can
only be measured at individual sites, e.g., by eddy covariance towers,
and an upscaling of these local observations is required to analyze
global patterns. Previous work focused on upscaling monthly, 8-day, or
daily average values, and global maps for each flux have been provided
accordingly. In this paper, we raise the upscaling of carbon and energy
fluxes between land and atmosphere to the next level by increasing the
temporal resolution to subdaily timescales. We provide continuous
half-hourly fluxes for the period from 2001 to 2014 at 0.5 degrees
spatial resolution, which allows for analyzing diurnal cycles globally.
The data set contains four fluxes: gross primary production (GPP), net
ecosystem exchange (NEE), latent heat (LE), and sensible heat (H). We
propose two prediction approaches for the diurnal cycles based on
large-scale regression models and compare them in extensive
cross-validation experiments using different sets of predictor
variables. We analyze the results for a set of FLUXNET tower sites
showing the suitability of our approaches for this upscaling task.
Finally, we have selected one approach to calculate the global
half-hourly data products based on predictor variables from remote
sensing and meteorology at daily resolution as well as half-hourly
potential radiation. In addition, we provide a derived product that only
contains monthly average diurnal cycles, which is a lightweight version
in terms of data storage that still allows studying the important
characteristics of diurnal patterns globally. We recommend to primarily
use these monthly average diurnal cycles, because they are less affected
by the impacts of day-to-day variation, observation noise, and
short-term fluctuations on subdaily timescales compared to the full
half-hourly flux products. The global half-hourly data products are
available at https://doi.org/10.17871/BACI.224.
BibTeX:
@article{bodesheim18a,
  author = {Bodesheim, Paul and Jung, Martin and Gans, Fabian and Mahecha, Miguel D. and Reichstein, Markus},
  title = {Upscaled diurnal cycles of land-atmosphere fluxes: a new global half-hourly data product},
  journal = {Earth System Science Data},
  year = {2018},
  volume = {10},
  number = {3},
  pages = {1327-1365},
  doi = {10.5194/essd-10-1327-2018}
}
Boland S, Bösch H, Brown L, Burrows J, Ciais P, Connor B, Crisp D, Denning S, Doney S, Engelen R and others (2009), "The need for atmospheric carbon dioxide measurements from space: Contributions from a rapid reflight of the Orbiting Carbon Observatory", White paper to NASA.
BibTeX:
@article{boland09a,
  author = {Boland, Stacey and Bösch, Hartmut and Brown, Linda and Burrows, John and Ciais, Philippe and Connor, Brian and Crisp, David and Denning, Scott and Doney, Scott and Engelen, Richard and others},
  title = {The need for atmospheric carbon dioxide measurements from space: Contributions from a rapid reflight of the Orbiting Carbon Observatory},
  journal = {White paper to NASA},
  year = {2009}
}
Bouche A, Beck-Winchatz B and Potosnak MJ ({2016}), "A high-altitude balloon platform for determining exchange of carbon dioxide over agricultural landscapes", ATMOSPHERIC MEASUREMENT TECHNIQUES., NOV 29, {2016}. Vol. {9}({12}), pp. 5707-5719.
Abstract: The exchange of carbon dioxide between the terrestrial biosphere and the
atmosphere is a key process in the global carbon cycle. Given emissions
from fossil fuel combustion and the appropriation of net primary
productivity by human activities, understanding the carbon dioxide
exchange of cropland agroecosystems is critical for evaluating future
trajectories of climate change. In addition, human manipulation of
agroecosystems has been proposed as a technique of removing carbon
dioxide from the atmosphere via practices such as no-tillage and cover
crops. We propose a novel method of measuring the exchange of carbon
dioxide over croplands using a high-altitude balloon (HAB) platform. The
HAB methodology measures two sequential vertical profiles of carbon
dioxide mixing ratio, and the surface exchange is calculated using a
fixed-mass column approach. This methodology is relatively inexpensive,
does not rely on any assumptions besides spatial homogeneity (no
horizontal advection) and provides data over a spatial scale between
stationary flux towers and satellite-based inversion calculations. The
HAB methodology was employed during the 2014 and 2015 growing seasons in
central Illinois, and the results are compared to satellite-based NDVI
values and a flux tower located relatively near the launch site in
Bondville, Illinois. These initial favorable results demonstrate the
utility of the methodology for providing carbon dioxide exchange data
over a large (10-100 km) spatial area. One drawback is its relatively
limited temporal coverage. While recruiting citizen scientists to
perform the launches could provide a more extensive dataset, the HAB
methodology is not appropriate for providing estimates of net annual
carbon dioxide exchange. Instead, a HAB dataset could provide an
important check for upscaling flux tower results and verifying
satellite-derived exchange estimates.
BibTeX:
@article{bouche16a,
  author = {Bouche, Angie and Beck-Winchatz, Bernhard and Potosnak, Mark J.},
  title = {A high-altitude balloon platform for determining exchange of carbon dioxide over agricultural landscapes},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {12},
  pages = {5707--5719},
  doi = {10.5194/amt-9-5707-2016}
}
Bovensmann H, Buchwitz M, Burrows JP, Reuter M, Krings T, Gerilowski K, Schneising O, Heymann J, Tretner A and Erzinger J ({2010}), "A remote sensing technique for global monitoring of power plant CO2 emissions from space and related applications", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {3}({4}), pp. 781-811.
Abstract: Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas
(GHG) causing global warming. The atmospheric CO2 concentration
increased by more than 30% since pre-industrial times - primarily due
to burning of fossil fuels - and still continues to increase. Reporting
of CO2 emissions is required by the Kyoto protocol. Independent
verification of reported emissions, which are typially not directly
measured, by methods such as inverse modeling of measured atmospheric
CO2 concentrations is currently not possible globally due to lack of
appropriate observations. Existing satellite instruments such as
SCIAMACHY/ENVISAT and TANSO/GOSAT focus on advancing our understanding
of natural CO2 sources and sinks. The obvious next step for future
generation satellites is to also constrain anthropogenic CO2 emissions.
Here we present a promising satellite remote sensing concept based on
spectroscopic measurements of reflected solar radiation and show, using
power plants as an example, that strong localized CO2 point sources can
be detected and their emissions quantified. This requires mapping the
atmospheric CO2 column distribution at a spatial resolution of 2x2 km(2)
with a precision of 0.5% (2 ppm) or better. We indicate that this can
be achieved with existing technology. For a single satellite in
sun-synchronous orbit with a swath width of 500 km, each power plant
(PP) is overflown every 6 days or more frequent. Based on the MODIS
cloud mask data product we conservatively estimate that typically 20
sufficiently cloud free overpasses per PP can be achieved every year. We
found that for typical wind speeds in the range of 2-6 m/s the
statistical uncertainty of the retrieved PP CO2 emission due to
instrument noise is in the range 1.6-4.8MtCO(2)/yr for single
overpasses. This corresponds to 12-36% of the emission of a mid-size PP
(13 MtCO(2)/yr). We have also determined the sensitivity to parameters
which may result in systematic errors such as atmospheric transport and
aerosol related parameters. We found that the emission error depends
linearly on wind speed, i.e., a 10% wind speed error results in a 10br> emission error, and that neglecting enhanced aerosol concentrations in
the PP plume may result in errors in the range 0.2-2.5 MtCO(2)/yr,
depending on PP aerosol emission. The discussed concept has the
potential to contribute to an independent verification of reported
anthropogenic CO2 emissions and therefore could be an important
component of a future global anthropogenic GHG emission monitoring
system. This is of relevance in the context of Kyoto protocol follow-on
agreements but also allows detection and monitoring of a variety of
other strong natural and anthropogenic CO2 and CH4 emitters. The
investigated instrument is not limited to these applications as it has
been specified to also deliver the data needed for global regional-scale
CO2 and CH4 surface flux inverse modeling.
BibTeX:
@article{bovensmann10a,
  author = {Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Reuter, M. and Krings, T. and Gerilowski, K. and Schneising, O. and Heymann, J. and Tretner, A. and Erzinger, J.},
  title = {A remote sensing technique for global monitoring of power plant CO2 emissions from space and related applications},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2010},
  volume = {3},
  number = {4},
  pages = {781--811},
  doi = {10.5194/amt-3-781-2010}
}
Bowman K, Liu J, Bloom A, Parazoo N, Lee M, Jiang Z, Menemenlis D, Gierach M, Collatz G, Gurney K and others (2017), "Global and Brazilian carbon response to El Niño Modoki 2011--2010", Earth and Space Science. Vol. 4(10), pp. 637-660.
BibTeX:
@article{bowman17a,
  author = {Bowman, KW and Liu, J and Bloom, AA and Parazoo, NC and Lee, M and Jiang, Z and Menemenlis, D and Gierach, MM and Collatz, GJ and Gurney, KR and others},
  title = {Global and Brazilian carbon response to El Niño Modoki 2011--2010},
  journal = {Earth and Space Science},
  year = {2017},
  volume = {4},
  number = {10},
  pages = {637--660}
}
Bozhinova DN (2015), "Interpreting plant-sampled?` 14CO2 to study regional anthropogenic CO2 signals in Europe" Wageningen University.
BibTeX:
@book{bozhinova15a,
  author = {Bozhinova, Denica Nikolaeva},
  title = {Interpreting plant-sampled?` 14CO2 to study regional anthropogenic CO2 signals in Europe},
  publisher = {Wageningen University},
  year = {2015}
}
Bril A, Oshchepkov S and Yokota T ({2009}), "Retrieval of atmospheric methane from high spectral resolution satellite measurements: a correction for cirrus cloud effects", APPLIED OPTICS., APR 10, {2009}. Vol. {48}({11}), pp. 2139-2148.
Abstract: We assessed the accuracy of methane (CH4) retrievals from synthetic
radiance spectra particular to Greenhouse Gases Observing Satellite
observations. We focused on estimating the CH4 vertical column amount
from an atmosphere that includes thin cirrus clouds, taking into account
uncertain meteorological conditions. A photon path-length probability
density function (PPDF)-based method was adapted to correct for
atmospheric scattering effects in CH4 retrievals. This method was shown
to provide similar retrieval accuracy as compared to a carbon dioxide
(CO2)-proxy-based correction approach. It infers some advantages of
PPDF-based method for methane retrievals under high variability of CO2
abundance. (C) 2009 Optical Society of America
BibTeX:
@article{bril09a,
  author = {Bril, Andrey and Oshchepkov, Sergey and Yokota, Tatsuya},
  title = {Retrieval of atmospheric methane from high spectral resolution satellite measurements: a correction for cirrus cloud effects},
  journal = {APPLIED OPTICS},
  year = {2009},
  volume = {48},
  number = {11},
  pages = {2139--2148},
  doi = {10.1364/AO.48.002139}
}
Brioude J, Petron G, Frost GJ, Ahmadov R, Angevine WM, Hsie EY, Kim SW, Lee SH, McKeen SA, Trainer M, Fehsenfeld FC, Holloway JS, Peischl J, Ryerson TB and Gurney KR ({2012}), "A new inversion method to calculate emission inventories without a prior at mesoscale: Application to the anthropogenic CO2 emission from Houston, Texas", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 10, {2012}. Vol. {117}
Abstract: We developed a new inversion method to calculate an emission inventory
for an anthropogenic pollutant without a prior emission estimate at
mesoscale. This method employs slopes between mixing ratio enhancements
of a given pollutant (CO2, for instance) with other co-emitted tracers
in conjunction with the emission inventories of those tracers (CO, NOy,
and SO2 are used in this example). The current application of this
method employed in situ measurements onboard the NOAA WP-3 research
aircraft during the 2006 Texas Air Quality Study (TexAQS 2006). We used
3 different transport models to estimate the uncertainties introduced by
the transport models in the inversion. We demonstrated the validity of
the new inversion method by calculating a 4 x 4 km(2) emission inventory
of anthropogenic CO2 in the Houston area in Texas, and comparing it to
the 10 x 10 km(2) Vulcan emission inventory for the same region. The
calculated anthropogenic CO2 inventory for the Houston Ship Channel,
home to numerous major industrial and port emission sources, showed
excellent agreement with Vulcan. The daytime CO2 average flux from the
Ship Channel is the largest urban CO2 flux reported in the literature.
Compared to Vulcan, the daytime urban area CO2 emissions were higher by
37% +/- 6%. Those differences can be explained by uncertainties in
emission factors in Vulcan and by increased emissions from point sources
and on-road emitters between 2002, the reference year in Vulcan, and
2006, the year that the TexAQS observations were made.
BibTeX:
@article{brioude12a,
  author = {Brioude, J. and Petron, G. and Frost, G. J. and Ahmadov, R. and Angevine, W. M. and Hsie, E. -Y. and Kim, S. -W. and Lee, S. -H. and McKeen, S. A. and Trainer, M. and Fehsenfeld, F. C. and Holloway, J. S. and Peischl, J. and Ryerson, T. B. and Gurney, K. R.},
  title = {A new inversion method to calculate emission inventories without a prior at mesoscale: Application to the anthropogenic CO2 emission from Houston, Texas},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2011JD016918}
}
Brioude J, Angevine WM, Ahmadov R, Kim SW, Evan S, McKeen SA, Hsie EY, Frost GJ, Neuman JA, Pollack IB, Peischl J, Ryerson TB, Holloway J, Brown SS, Nowak JB, Roberts JM, Wofsy SC, Santoni GW, Oda T and Trainer M ({2013}), "Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({7}), pp. 3661-3677.
Abstract: We present top-down estimates of anthropogenic CO, NOx and CO2 surface
fluxes at mesoscale using a Lagrangian model in combination with three
different WRF model configurations, driven by data from aircraft flights
during the CALNEX campaign in southern California in May-June 2010. The
US EPA National Emission Inventory 2005 (NEI 2005) was the prior in the
CO and NOx inversion calculations. The flux ratio inversion method,
based on linear relationships between chemical species, was used to
calculate the CO2 inventory without prior knowledge of CO2 surface
fluxes. The inversion was applied to each flight to estimate the
variability of single-flight-based flux estimates. In Los Angeles (LA)
County, the uncertainties on CO and NOx fluxes were 10% and 15
respectively. Compared with NEI 2005, the CO posterior emissions were
lower by 43% in LA County and by 37% in the South Coast Air Basin
(SoCAB). NOx posterior emissions were lower by 32% in LA County and by
27% in the SoCAB. NOx posterior emissions were 40% lower on weekends
relative to weekdays. The CO2 posterior estimates were 183 Tgyr(-1) in
SoCAB. A flight during ITCT (Intercontinental Transport and Chemical
Transformation) in 2002 was used to estimate emissions in the LA Basin
in 2002. From 2002 to 2010, the CO and NOx posterior emissions decreased
by 41% and 37 respectively, in agreement with previous studies. Over
the same time period, CO2 emissions increased by 10% in LA County but
decreased by 4% in the SoCAB, a statistically insignificant change.
Overall, the posterior estimates were in good agreement with the
California Air Resources Board (CARB) inventory, with differences of
15% or less. However, the posterior spatial distribution in the basin
was significantly different from CARB for NOx emissions. WRF-Chem
mesoscale chemical-transport model simulations allowed an evaluation of
differences in chemistry using different inventory assumptions,
including NEI 2005, a gridded CARB inventory and the posterior
inventories derived in this study. The biases in WRF-Chem ozone were
reduced and correlations were increased using the posterior from this
study compared with simulations with the two bottom-up inventories,
suggesting that improving the spatial distribution of ozone precursor
surface emissions is also important in mesoscale chemistry simulations.
BibTeX:
@article{brioude13a,
  author = {Brioude, J. and Angevine, W. M. and Ahmadov, R. and Kim, S. -W. and Evan, S. and McKeen, S. A. and Hsie, E. -Y. and Frost, G. J. and Neuman, J. A. and Pollack, I. B. and Peischl, J. and Ryerson, T. B. and Holloway, J. and Brown, S. S. and Nowak, J. B. and Roberts, J. M. and Wofsy, S. C. and Santoni, G. W. and Oda, T. and Trainer, M.},
  title = {Top-down estimate of surface flux in the Los Angeles Basin using a mesoscale inverse modeling technique: assessing anthropogenic emissions of CO, NOx and CO2 and their impacts},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {7},
  pages = {3661--3677},
  doi = {10.5194/acp-13-3661-2013}
}
Brondfield MN, Hutyra LR, Gately CK, Raciti SM and Peterson SA ({2012}), "Modeling and validation of on-road CO2 emissions inventories at the urban regional scale", ENVIRONMENTAL POLLUTION., NOV, {2012}. Vol. {170}, pp. 113-123.
Abstract: On-road emissions are a major contributor to rising concentrations of
atmospheric greenhouse gases. In this study, we applied a downscaling
methodology based on commonly available spatial parameters to model
on-road CO2 emissions at the 1 x 1 km scale for the Boston. MA region
and tested our approach with surface-level CO2 observations. Using two
previously constructed emissions inventories with differing spatial
patterns and underlying data sources, we developed regression models
based on impervious surface area and volume-weighted road density that
could be scaled to any resolution. We found that the models accurately
reflected the inventories at their original scales (R-2 = 0.63 for both
models) and exhibited a strong relationship with observed CO2 mixing
ratios when downscaled across the region. Moreover, the improved spatial
agreement of the models over the original inventories confirmed that
either product represents a viable basis for downscaling in other
metropolitan regions, even with limited data. (c) 2012 Elsevier Ltd. All
rights reserved.
BibTeX:
@article{brondfield12a,
  author = {Brondfield, Max N. and Hutyra, Lucy R. and Gately, Conor K. and Raciti, Steve M. and Peterson, Scott A.},
  title = {Modeling and validation of on-road CO2 emissions inventories at the urban regional scale},
  journal = {ENVIRONMENTAL POLLUTION},
  year = {2012},
  volume = {170},
  pages = {113--123},
  doi = {10.1016/j.envpol.2012.06.003}
}
Brooks BGJ, Desai AR, Stephens BB, Bowling DR, Burns SP, Watt AS, Heck SL and Sweeney C ({2012}), "Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({4}), pp. 2099-2115.
Abstract: There is a widely recognized need to improve our understanding of
biosphere-atmosphere carbon exchanges in areas of complex terrain
including the United States Mountain West. CO2 fluxes over mountainous
terrain are often difficult to measure due to unusual and complicated
influences associated with atmospheric transport. Consequently, deriving
regional fluxes in mountain regions with carbon cycle inversion of
atmospheric CO2 mole fraction is sensitive to filtering of observations
to those that can be represented at the transport model resolution.
Using five years of CO2 mole fraction observations from the Regional
Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky
RACCOON), five statistical filters are used to investigate a range of
approaches for identifying regionally representative CO2 mole fractions.
Test results from three filters indicate that subsets based on
short-term variance and local CO2 gradients across tower inlet heights
retain nine-tenths of the total observations and are able to define
representative diel variability and seasonal cycles even for
difficult-to-model sites where the influence of local fluxes is much
larger than regional mole fraction variations. Test results from two
other filters that consider measurements from previous and following
days using spline fitting or sliding windows are overly selective. Case
study examples showed that these windowing-filters rejected measurements
representing synoptic changes in CO2, which suggests that they are not
well suited to filtering continental CO2 measurements. We present a
novel CO2 lapse rate filter that uses CO2 differences between levels in
the model atmosphere to select subsets of site measurements that are
representative on model scales. Our new filtering techniques provide
guidance for novel approaches to assimilating mountain-top CO2 mole
fractions in carbon cycle inverse models.
BibTeX:
@article{brooks12a,
  author = {Brooks, B. -G. J. and Desai, A. R. and Stephens, B. B. and Bowling, D. R. and Burns, S. P. and Watt, A. S. and Heck, S. L. and Sweeney, C.},
  title = {Assessing filtering of mountaintop CO2 mole fractions for application to inverse models of biosphere-atmosphere carbon exchange},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2012},
  volume = {12},
  number = {4},
  pages = {2099--2115},
  doi = {10.5194/acp-12-2099-2012}
}
Bruhwiler L, Dlugokencky E, Masarie K, Ishizawa M, Andrews A, Miller J, Sweeney C, Tans P and Worthy D ({2014}), "CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({16}), pp. 8269-8293.
Abstract: We describe an assimilation system for atmospheric methane (CH4),
CarbonTracker-CH4, and demonstrate the diagnostic value of global or
zonally averaged CH4 abundances for evaluating the results. We show that
CarbonTracker-CH4 is able to simulate the observed zonal average mole
fractions and capture inter-annual variability in emissions quite well
at high northern latitudes (53-90 degrees N). In contrast,
CarbonTracker-CH4 is less successful in the tropics where there are few
observations and therefore misses significant variability and is more
influenced by prior flux estimates. CarbonTracker-CH4 estimates of total
fluxes at high northern latitudes are about 81+/- 7 TgCH(4) yr-1, about
12 TgCH(4) yr-1 (13 lower than prior estimates, a result that is
consistent with other atmospheric inversions. Emissions from European
wetlands are decreased by 30 a result consistent with previous work
by Bergamaschi et al. (2005); however, unlike their results, emissions
from wetlands in boreal Eurasia are increased relative to the prior
estimate. Although CarbonTracker-CH4 does not estimate an increasing
trend in emissions from high northern latitudes for 2000 through 2010,
significant inter-annual variability in high northern latitude fluxes is
recovered. Exceptionally warm growing season temperatures in the Arctic
occurred in 2007, a year that was also anonymously wet. Estimated
emissions from natural sources were greater than the decadal average by
4.4+/- 3.8 TgCH(4) yr(-1) in 2007.
CarbonTracker-CH4 estimates for temperate latitudes are only slightly
increased over prior estimates, but about 10 TgCH(4) yr(-1) is
redistributed from Asia to North America. This difference exceeds the
estimated uncertainty for North America (+/- 3.5 TgCH(4) yr(-1)). We
used time invariant prior flux estimates, so for the period from 2000 to
2006, when the growth rate of global atmospheric CH4 was very small, the
assimilation does not produce increases in natural or anthropogenic
emissions in contrast to bottom-up emission data sets. After 2006, when
atmospheric CH4 began its recent increases, CarbonTracker-CH4 allocates
some of the increases to anthropogenic emissions at temperate latitudes,
and some to tropical wetland emissions. For temperate North America the
prior flux increases by about 4 TgCH(4) yr(-1) during winter when
biogenic emissions are small. Examination of the residuals at some North
American observation sites suggests that increased gas and oil
exploration may play a role since sites near fossil fuel production are
particularly hard for the inversion to fit and the prior flux estimates
at these sites are apparently lower and lower over time than what the
atmospheric measurements imply.
The tropics are not currently well resolved by CarbonTracker-CH4 due to
sparse observational coverage and a short assimilation window. However,
there is a small uncertainty reduction and posterior emissions are about
18% higher than prior estimates. Most of this increase is allocated to
tropical South America rather than being distributed among the global
tropics. Our estimates for this source region are about 32+/- 4 TgCH(4)
yr(-1), in good agreement with the analysis of Melack et al. (2004) who
obtained 29 TgCH(4) yr(-1) for the most productive region, the Amazon
Basin.
BibTeX:
@article{bruhwiler14a,
  author = {Bruhwiler, L. and Dlugokencky, E. and Masarie, K. and Ishizawa, M. and Andrews, A. and Miller, J. and Sweeney, C. and Tans, P. and Worthy, D.},
  title = {CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {16},
  pages = {8269--8293},
  doi = {10.5194/acp-14-8269-2014}
}
Buchwitz M, Schneising O, Burrows JP, Bovensmann H, Reuter M and Notholt J ({2007}), "First direct observation of the atmospheric CO2 year-to-year increase from space", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {7}({16}), pp. 4249-4256.
BibTeX:
@article{buchwitz07a,
  author = {Buchwitz, M. and Schneising, O. and Burrows, J. P. and Bovensmann, H. and Reuter, M. and Notholt, J.},
  title = {First direct observation of the atmospheric CO2 year-to-year increase from space},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2007},
  volume = {7},
  number = {16},
  pages = {4249--4256}
}
Buchwitz M, Reuter M, Schneising O, Heymann J, Bovensmann H and Burrows J (2009), "Towards an improved CO2 retrieval algorithm for SCIAMACHY on ENVISAT", In Proceedings Atmospheric Science Conference, Barcelona, Spain. , pp. 7-11.
BibTeX:
@inproceedings{buchwitz09a,
  author = {Buchwitz, M and Reuter, M and Schneising, O and Heymann, J and Bovensmann, H and Burrows, JP},
  title = {Towards an improved CO2 retrieval algorithm for SCIAMACHY on ENVISAT},
  booktitle = {Proceedings Atmospheric Science Conference, Barcelona, Spain},
  year = {2009},
  pages = {7--11}
}
Buchwitz M, Bovensmann H, Burrows J, Schneising O and Reuter M (2010), "Global mapping of methane and carbon dioxide: from SCIAMACHY to CarbonSat", In Proceedings ESA-iLEAPS-EGU conference on earth observation for land-atmosphere interaction science, ESA Special Publications SP-688, ESRIN, Italy. , pp. 3-5.
BibTeX:
@inproceedings{buchwitz10a,
  author = {Buchwitz, M and Bovensmann, H and Burrows, JP and Schneising, O and Reuter, M},
  title = {Global mapping of methane and carbon dioxide: from SCIAMACHY to CarbonSat},
  booktitle = {Proceedings ESA-iLEAPS-EGU conference on earth observation for land-atmosphere interaction science, ESA Special Publications SP-688, ESRIN, Italy},
  year = {2010},
  pages = {3--5},
  url = {http://tratin.cinvestav.mx/Portals/0/PapersADM/B/Buchwitz%20et%20al%202011%20global%20mapping%20sciamachy%20carbonsat.pdf}
}
Buchwitz M, Reuter M, Schneising O, Boesch H, Aben I, Alexe M, Armante R, Bergamaschi P, Bovensmann H, Brunner D, Buchmann B, Burrows JP, Butz A, Chevallier F, Chedin A, Crevoisier CD, Gonzi S, De Maziere M, De Wachter E, Detmers R, Dils B, Frankenberg C, Hahne P, Hasekamp OP, Hewson W, Heymann J, Houweling S, Hilker M, Kaminski T, Kuhlmann G, Laeng A, v Leeuwen TT, Lichtenberg G, Marshall J, Noel S, Notholt J, Palmer P, Parker R, Scholze M, Stiller GP, Warneke T and Zehner C ({2015}), "THE GREENHOUSE GAS PROJECT OF ESA'S CLIMATE CHANGE INITIATIVE (GHG-CCI): OVERVIEW, ACHIEVEMENTS AND FUTURE PLANS", In 36TH INTERNATIONAL SYMPOSIUM ON REMOTE SENSING OF ENVIRONMENT. Vol. {47}({W3}), pp. 165-172.
Abstract: The GHG-CCI project (http://www.esa-ghg-cci.org/) is one of several
projects of the European Space Agency's (ESA) Climate Change Initiative
(CCI). The goal of the CCI is to generate and deliver data sets of
various satellite-derived Essential Climate Variables (ECVs) in line
with GCOS (Global Climate Observing System) requirements. The ``ECV
Greenhouse Gases'' (ECV GHG) is the global distribution of important
climate relevant gases - namely atmospheric CO2 and CH4 - with a quality
sufficient to obtain information on regional CO2 and CH4 sources and
sinks. The main goal of GHG-CCI is to generate long-term highly accurate
and precise time series of global near-surface-sensitive satellite
observations of CO2 and CH4, i.e., XCO2 and XCH4, starting with the
launch of ESA's ENVISAT satellite. These products are currently
retrieved from SCIAMACHY/ENVISAT (2002-2012) and TANSO-FTS/GOSAT
(2009-today) nadir mode observations in the
near-infrared/shortwave-infrared spectral region. In addition, other
sensors (e.g., IASI and MIPAS) and viewing modes (e.g., SCIAMACHY solar
occultation) are also considered and in the future also data from other
satellites. The GHG-CCI data products and related documentation are
freely available via the GHG-CCI website and yearly updates are
foreseen. Here we present an overview about the latest data set (Climate
Research Data Package No. 2 (CRDP2)) and summarize key findings from
using satellite CO2 and CH4 retrievals to improve our understanding of
the natural and anthropogenic sources and sinks of these important
atmospheric greenhouse gases. We also shortly mention ongoing activities
related to validation and initial user assessment of CRDP2 and future
plans.
BibTeX:
@inproceedings{buchwitz15a,
  author = {Buchwitz, M. and Reuter, M. and Schneising, O. and Boesch, H. and Aben, I. and Alexe, M. and Armante, R. and Bergamaschi, P. and Bovensmann, H. and Brunner, D. and Buchmann, B. and Burrows, J. P. and Butz, A. and Chevallier, F. and Chedin, A. and Crevoisier, C. D. and Gonzi, S. and De Maziere, M. and De Wachter, E. and Detmers, R. and Dils, B. and Frankenberg, C. and Hahne, P. and Hasekamp, O. P. and Hewson, W. and Heymann, J. and Houweling, S. and Hilker, M. and Kaminski, T. and Kuhlmann, G. and Laeng, A. and v Leeuwen, T. T. and Lichtenberg, G. and Marshall, J. and Noel, S. and Notholt, J. and Palmer, P. and Parker, R. and Scholze, M. and Stiller, G. P. and Warneke, T. and Zehner, C.},
  editor = {Schreier, G and Skrovseth, PE and Staudenrausch, H},
  title = {THE GREENHOUSE GAS PROJECT OF ESA'S CLIMATE CHANGE INITIATIVE (GHG-CCI): OVERVIEW, ACHIEVEMENTS AND FUTURE PLANS},
  booktitle = {36TH INTERNATIONAL SYMPOSIUM ON REMOTE SENSING OF ENVIRONMENT},
  year = {2015},
  volume = {47},
  number = {W3},
  pages = {165--172},
  note = {36th International Symposium on Remote Sensing of the Environment (ISRSE), Berlin, GERMANY, MAY 11-15, 2015},
  doi = {10.5194/isprsarchives-XL-7-W3-165-2015}
}
Buchwitz M, Reuter M, Schneising O, Hewson W, Detmers RG, Boesch H, Hasekamp OP, Aben I, Bovensmann H, Burrows JP, Butz A, Chevallier F, Dils B, Frankenberg C, Heymann J, Lichtenberg G, De Maziere M, Notholt J, Parker R, Warneke T, Zehner C, Griffith DWT, Deutscher NM, Kuze A, Suto H and Wunch D ({2017}), "Global satellite observations of column-averaged carbon dioxide and methane: The GHG-CCI XCO2 and XCH4 CRDP3 data set", REMOTE SENSING OF ENVIRONMENT., DEC 15, {2017}. Vol. {203}, pp. 276-295.
Abstract: Carbon dioxide (CO2) and methane (CH4) are the two most important
greenhouse gases emitted by mankind. Better knowledge of the surface
sources and sinks of these Essential Climate Variables (ECVs) and
related carbon uptake and release processes is needed for important
climate change related applications such as improved climate modelling
and prediction. Some satellites provide near-surface-sensitive
atmospheric CO2 and CH4 observations that can be used to obtain
information on CQ(2) and CH4 surface fluxes. The goal of the GHG-CCI
project of the European Space Agency's (ESA) Climate Change Initiative
(CCI) is to use satellite data to generate atmospheric CO2 and CH4 data
products meeting demanding GCOS (Global Climate Observing System)
greenhouse gas (GHG) ECV requirements. To achieve this, retrieval
algorithms are regularly being improved followed by annual data
reprocessing and analysis cycles to generate better products in terms of
extended time series and continuously improved data quality. Here we
present an overview about the latest GHG-CCI data set called Climate
Research Data Package No.3 (CRDP3) focusing on the GHG-CCI core data
products, which are column-averaged dry air mole fractions of CO2 and
CH4, i.e., XCO2 and XCH4, as retrieved from SCIAMACHY/ENVISAT and
TANSO/GOSAT satellite radiances covering the time period end of 2002 to
end of 2014. We present global maps and time series including initial
validation results obtained by comparisons with Total Carbon Column
Observing Network (TCCON) ground-based observations. We show that the
GCOS requirements for systematic error (<1 ppm for XCO2, <10 ppb for
XCH4) and long-term stability (<0.2 ppm/year for XCO2, <2 ppb/year for
XCH4) are met for nearly all products (an exception is SCIAMACHY methane
especially since 2010). For XCO2 we present comparisons with global
models using the output of two CO2 assimilation systems (MACC version
14r2 and CarbonTracker version CT2013B). We show that overall there is
reasonable consistency and agreement between all data sets (within-1-2
ppm) but we also found significant differences depending on region and
time period. (C) 2017 Elsevier Inc. All rights reserved.
BibTeX:
@article{buchwitz17a,
  author = {Buchwitz, M. and Reuter, M. and Schneising, O. and Hewson, W. and Detmers, R. G. and Boesch, H. and Hasekamp, O. P. and Aben, I. and Bovensmann, H. and Burrows, J. P. and Butz, A. and Chevallier, F. and Dils, B. and Frankenberg, C. and Heymann, J. and Lichtenberg, G. and De Maziere, M. and Notholt, J. and Parker, R. and Warneke, T. and Zehner, C. and Griffith, D. W. T. and Deutscher, N. M. and Kuze, A. and Suto, H. and Wunch, D.},
  title = {Global satellite observations of column-averaged carbon dioxide and methane: The GHG-CCI XCO2 and XCH4 CRDP3 data set},
  journal = {REMOTE SENSING OF ENVIRONMENT},
  year = {2017},
  volume = {203},
  pages = {276--295},
  doi = {10.1016/j.rse.2016.12.027}
}
Buchwitz M, Reuter M, Schneising O, Noel S, Gier B, Bovensmann H, Burrows JP, Boesch H, Anand J, Parker RJ, Somkuti P, Detmers RG, Hasekamp OP, Aben I, Butz A, Kuze A, Suto H, Yoshida Y, Crisp D and O'Dell C ({2018}), "Computation and analysis of atmospheric carbon dioxide annual mean growth rates from satellite observations during 2003-2016", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 7, {2018}. Vol. {18}({23}), pp. 17355-17370.
Abstract: The growth rate of atmospheric carbon dioxide (CO2) reflects the net
effect of emissions and uptake resulting from anthropogenic and natural
carbon sources and sinks. Annual mean CO2 growth rates have been
determined from satellite retrievals of column-averaged dry-air mole
fractions of CO2, i.e. XCO2, for the years 2003 to 2016. The XCO2 growth
rates agree with National Oceanic and Atmospheric Administration (NOAA)
growth rates from CO2 surface observations within the uncertainty of the
satellite-derived growth rates (mean difference +/- standard deviation:
0.0 +/- 0.3 ppm year(-1); R: 0.82). This new and independent data set
confirms record-large growth rates of around 3 ppm year(-1) in 2015 and
2016, which are attributed to the 2015-2016 El Nino. Based on a
comparison of the satellite-derived growth rates with human CO2
emissions from fossil fuel combustion and with El Nino Southern
Oscillation (ENSO) indices, we estimate by how much the impact of ENSO
dominates the impact of fossil-fuel-burning-related emissions in
explaining the variance of the atmospheric CO2 growth rate. Our analysis
shows that the ENSO impact on CO2 growth rate variations dominates that
of human emissions throughout the period 2003-2016 but in particular
during the period 2010-2016 due to strong La Nina and El Nino events.
Using the derived growth rates and their uncertainties, we estimate the
probability that the impact of ENSO on the variability is larger than
the impact of human emissions to be 63 % for the time period 2003-2016.
If the time period is restricted to 2010-2016, this probability
increases to 94%.
BibTeX:
@article{buchwitz18a,
  author = {Buchwitz, Michael and Reuter, Maximilian and Schneising, Oliver and Noel, Stefan and Gier, Bettina and Bovensmann, Heinrich and Burrows, John P. and Boesch, Hartmut and Anand, Jasdeep and Parker, Robert J. and Somkuti, Peter and Detmers, Rob G. and Hasekamp, Otto P. and Aben, Ilse and Butz, Andre and Kuze, Akihiko and Suto, Hiroshi and Yoshida, Yukio and Crisp, David and O'Dell, Christopher},
  title = {Computation and analysis of atmospheric carbon dioxide annual mean growth rates from satellite observations during 2003-2016},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2018},
  volume = {18},
  number = {23},
  pages = {17355--17370},
  doi = {10.5194/acp-18-17355-2018}
}
Burgin MS (2014), "Physics-based modeling for high-fidelity radar retrievals". Thesis at: University of Michigan.
BibTeX:
@phdthesis{burgin14a,
  author = {Burgin, Mariko Sofie},
  title = {Physics-based modeling for high-fidelity radar retrievals},
  school = {University of Michigan},
  year = {2014}
}
Buschmann M, Deutscher NM, Sherlock V, Palm M, Warneke T and Notholt J ({2016}), "Retrieval of xCO(2) from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({2}), pp. 577-585.
Abstract: High-resolution solar absorption spectra, taken within the Network for
the Detection of Atmospheric Composition Change Infrared Working Group
(NDACC-IRWG) in the mid-infrared spectral region, are used to infer
partial or total column abundances of many gases. In this paper we
present the retrieval of a column-averaged mole fraction of carbon
dioxide from NDACC-IRWG spectra taken with a Fourier transform infrared
(FTIR) spectrometer at the site in Ny-Alesund, Spitsbergen. The
retrieved time series is compared to colocated standard TCCON (Total
Carbon Column Observing Network) measurements of column-averaged dry-air
mole fractions of CO2 (denoted by xCO(2)). Comparing the NDACC and TCCON
retrievals, we find that the sensitivity of the NDACC retrieval is lower
in the troposphere (by a factor of 2) and higher in the stratosphere,
compared to TCCON. Thus, the NDACC retrieval is less sensitive to
tropospheric changes (e.g., the seasonal cycle) in the column average.
BibTeX:
@article{buschmann16a,
  author = {Buschmann, Matthias and Deutscher, Nicholas M. and Sherlock, Vanessa and Palm, Mathias and Warneke, Thorsten and Notholt, Justus},
  title = {Retrieval of xCO(2) from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {2},
  pages = {577--585},
  doi = {10.5194/amt-9-577-2016}
}
Butler MP, Davis KJ, Denning AS and Kawa SR ({2010}), "Using continental observations in global atmospheric inversions of CO2: North American carbon sources and sinks", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 550-572.
Abstract: We evaluate North American carbon fluxes using a monthly global Bayesian
synthesis inversion that includes well-calibrated carbon dioxide
concentrations measured at continental flux towers. We employ the NASA
Parametrized Chemistry Tracer Model (PCTM) for atmospheric transport and
a TransCom-style inversion with subcontinental resolution. We subsample
carbon dioxide time series at four North American flux tower sites for
mid-day hours to ensure sampling of a deep, well-mixed atmospheric
boundary layer. The addition of these flux tower sites to a global
network reduces North America mean annual flux uncertainty for 2001-2003
by 20% to 0.4 Pg C yr-1 compared to a network without the tower sites.
North American flux is estimated to be a net sink of 1.2 +/- 0.4 Pg C
yr-1 which is within the uncertainty bounds of the result without the
towers. Uncertainty reduction is found to be local to the regions within
North America where the flux towers are located, and including the
towers reduces covariances between regions within North America. Mid-day
carbon dioxide observations from flux towers provide a viable means of
increasing continental observation density and reducing the uncertainty
of regional carbon flux estimates in atmospheric inversions.
BibTeX:
@article{butler10a,
  author = {Butler, M. P. and Davis, K. J. and Denning, A. S. and Kawa, S. R.},
  title = {Using continental observations in global atmospheric inversions of CO2: North American carbon sources and sinks},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {550--572},
  doi = {10.1111/j.1600-0889.2010.00501.x}
}
Butz A, Hasekamp OP, Frankenberg C, Vidot J and Aben I ({2010}), "CH4 retrievals from space-based solar backscatter measurements: Performance evaluation against simulated aerosol and cirrus loaded scenes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 16, {2010}. Vol. {115}
Abstract: Monitoring of atmospheric methane (CH4) concentrations from space-based
instruments such as the Scanning Imaging Absorption Spectrometer for
Atmospheric Chartography (SCIAMACHY) and the Greenhouse Gases Observing
Satellite (GOSAT) relies on observations of sunlight backscattered to
space by the Earth's surface and atmosphere. Retrieval biases occur due
to unaccounted scattering effects by aerosols and thin cirrus that
modify the lightpath. Here, we evaluate the accuracy of two retrieval
methods that aim at minimizing such scattering induced errors. The
lightpath ``proxy'' method, applicable to SCIAMACHY and GOSAT,
retrieves CH4 and carbon dioxide (CO2) simultaneously and uses CO2 as a
proxy for lightpath modification. The ``physics-based'' method, which
we propose for GOSAT, aims at simultaneously retrieving CH4
concentrations and scattering properties of the atmosphere. We evaluate
performance of the methods against a trial ensemble of simulated aerosol
and cirrus loaded scenes. More than 80% of the trials yield residual
scattering induced CH4 errors below 0.6% and 0.8% for the proxy and
the physics-based approach, respectively. Very few cases result in
errors greater than 2% for both methods. Advantages of the proxy
approach are efficient and robust performance yielding more useful
retrievals than the physics-based method which reveals some
nonconvergent cases. The major disadvantage of the proxy method is the
uncertainty of the proxy CO2 concentration contributing to the overall
error budget. Residual errors generally correlate with particle and
surface properties and thus might impact inverse modeling of CH4 sources
and sinks.
BibTeX:
@article{butz10a,
  author = {Butz, A. and Hasekamp, O. P. and Frankenberg, C. and Vidot, J. and Aben, I.},
  title = {CH4 retrievals from space-based solar backscatter measurements: Performance evaluation against simulated aerosol and cirrus loaded scenes},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2010},
  volume = {115},
  doi = {10.1029/2010JD014514}
}
Butz A, Guerlet S, Hasekamp O, Schepers D, Galli A, Aben I, Frankenberg C, Hartmann JM, Tran H, Kuze A, Keppel-Aleks G, Toon G, Wunch D, Wennberg P, Deutscher N, Griffith D, Macatangay R, Messerschmidt J, Notholt J and Warneke T ({2011}), "Toward accurate CO2 and CH4 observations from GOSAT", GEOPHYSICAL RESEARCH LETTERS., JUL 30, {2011}. Vol. {38}
Abstract: The column-average dry air mole fractions of atmospheric carbon dioxide
and methane (X-CO2 and X-CH4) are inferred from observations of
backscattered sunlight conducted by the Greenhouse gases Observing
SATellite (GOSAT). Comparing the first year of GOSAT retrievals over
land with colocated ground-based observations of the Total Carbon Column
Observing Network (TCCON), we find an average difference (bias) of
-0.05% and -0.30% for X-CO2 and X-CH4 with a station-to-station
variability (standard deviation of the bias) of 0.37% and 0.26% among
the 6 considered TCCON sites. The root-mean square deviation of the
bias-corrected satellite retrievals from colocated TCCON observations
amounts to 2.8 ppm for X-CO2 and 0.015 ppm for X-CH4. Without any data
averaging, the GOSAT records reproduce general source/sink patterns such
as the seasonal cycle of X-CO2 suggesting the use of the satellite
retrievals for constraining surface fluxes. Citation: Butz, A., et al.
(2011), Toward accurate CO2 and CH4 observations from GOSAT, Geophys.
Res. Lett., 38, L14812, doi:10.1029/2011GL047888.
BibTeX:
@article{butz11a,
  author = {Butz, A. and Guerlet, S. and Hasekamp, O. and Schepers, D. and Galli, A. and Aben, I. and Frankenberg, C. and Hartmann, J. -M. and Tran, H. and Kuze, A. and Keppel-Aleks, G. and Toon, G. and Wunch, D. and Wennberg, P. and Deutscher, N. and Griffith, D. and Macatangay, R. and Messerschmidt, J. and Notholt, J. and Warneke, T.},
  title = {Toward accurate CO2 and CH4 observations from GOSAT},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2011},
  volume = {38},
  doi = {10.1029/2011GL047888}
}
Butz A, Guerlet S, Hasekamp OP, Kuze A and Suto H ({2013}), "Using ocean-glint scattered sunlight as a diagnostic tool for satellite remote sensing of greenhouse gases", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({9}), pp. 2509-2520.
Abstract: Spectroscopic measurements of sunlight backscattered by the Earth's
surface is a technique widely used for remote sensing of atmospheric
constituent concentrations from space. Thereby, remote sensing of
greenhouse gases poses particularly challenging accuracy requirements
for instrumentation and retrieval algorithms which, in general, suffer
from various error sources. Here, we investigate a method that helps
disentangle sources of error for observations of sunlight backscattered
from the glint spot on the ocean surface. The method exploits the
backscattering characteristics of the ocean surface, which is bright for
glint geometry but dark for off-glint angles. This property allows for
identifying a set of clean scenes where light scattering due to
particles in the atmosphere is negligible such that uncertain knowledge
of the lightpath can be excluded as a source of error. We apply the
method to more than 3 yr of ocean-glint measurements by the Thermal And
Near infrared Sensor for carbon Observation (TANSO) Fourier Transform
Spectrometer (FTS) onboard the Greenhouse Gases Observing Satellite
(GOSAT), which aims at measuring carbon dioxide (CO2) and methane (CH4)
concentrations. The proposed method is able to clearly monitor recent
improvements in the instrument calibration of the oxygen (O-2) A-band
channel and suggests some residual uncertainty in our knowledge about
the instrument. We further assess the consistency of CO2 retrievals from
several absorption bands between 6400 cm(-1) (1565 nm) and 4800 cm(-1)
(2100 nm) and find that the absorption bands commonly used for
monitoring of CO2 dry air mole fractions from GOSAT allow for
consistency better than 1.5 ppm. Usage of other bands reveals
significant inconsistency among retrieved CO2 concentrations pointing at
inconsistency of spectroscopic parameters.
BibTeX:
@article{butz13a,
  author = {Butz, A. and Guerlet, S. and Hasekamp, O. P. and Kuze, A. and Suto, H.},
  title = {Using ocean-glint scattered sunlight as a diagnostic tool for satellite remote sensing of greenhouse gases},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2013},
  volume = {6},
  number = {9},
  pages = {2509--2520},
  doi = {10.5194/amt-6-2509-2013}
}
Butz A, Orphal J, Checa-Garcia R, Friedl-Vallon F, von Clarmann T, Bovensmann H, Hasekamp O, Landgraf J, Knigge T, Weise D, Sqalli-Houssini O and Kemper D ({2015}), "Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({11}), pp. 4719-4734.
Abstract: The Geostationary Emission Explorer for Europe (G3E) is a concept for a
geostationary satellite sounder that aims to constrain the sources and
sinks of greenhouse gases carbon dioxide (CO2) and methane (CH4) for
continental-scale regions. Its primary focus is on central Europe. G3E
carries a spectrometer system that collects sunlight backscattered from
the Earth's surface and atmosphere in the near-infrared (NIR) and
shortwave-infrared (SWIR) spectral range. Solar absorption spectra allow
for spatiotemporally dense observations of the column-average
concentrations of carbon dioxide (XCO2), methane (XCH4), and carbon
monoxide (XCO). The mission concept in particular facilitates sampling
of the diurnal variation with several measurements per day during
summer.
Here, we present the mission concept and carry out an initial
performance assessment of the retrieval capabilities. The radiometric
performance of the 4 grating spectrometers is tuned to reconcile small
ground-pixel sizes (similar to 2 km x 3 km at 50 degrees latitude) with
short single-shot exposures (similar to 2.9 s) that allow for sampling
continental regions such as central Europe within 2 h while providing a
sufficient signal-to-noise ratio. The noise errors to be expected for
XCO2, XCH4, and XCO are assessed through retrieval simulations for a
European trial ensemble. Generally, single-shot precision for the
targeted XCO2 and XCH4 is better than 0.5% with some exception for
scenes with low infrared surface albedo observed under low sun
conditions in winter. For XCO, precision is generally better than 10 br> Performance for aerosol and cirrus loaded atmospheres is assessed by
mimicking G3E's slant view on Europe for an ensemble of atmospheric
scattering properties used previously for evaluating nadir-viewing
low-Earth-orbit (LEO) satellites. While retrieval concepts developed for
LEO configurations generally succeed in mitigating aerosol- and
cirrus-induced retrieval errors for G3E's setup, residual errors are
somewhat greater in geostationary orbit (GEO) than in LEO. G3E's
deployment in the vicinity of the Meteosat Third Generation (MTG)
satellites has the potential to make synergistic use of MTG's sounding
capabilities e.g. with respect to characterization of aerosol and cloud
properties or with respect to enhancing carbon monoxide retrievals by
combining G3E's solar and MTG's thermal infrared spectra.
BibTeX:
@article{butz15a,
  author = {Butz, A. and Orphal, J. and Checa-Garcia, R. and Friedl-Vallon, F. and von Clarmann, T. and Bovensmann, H. and Hasekamp, O. and Landgraf, J. and Knigge, T. and Weise, D. and Sqalli-Houssini, O. and Kemper, D.},
  title = {Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {11},
  pages = {4719--4734},
  doi = {10.5194/amt-8-4719-2015}
}
Byrne B, Jones DBA, Strong K, Zeng ZC, Deng F and Liu J ({2017}), "Sensitivity of CO2 surface flux constraints to observational coverage", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 27, {2017}. Vol. {122}({12}), pp. 6672-6694.
Abstract: Inverse modeling of regional CO2 fluxes using atmospheric CO2 data is
sensitive to the observational coverage of the observing network. Here
we use the GEOS-Chem adjoint model to examine the sensitivity to CO2
fluxes of observations from the in situ surface network, the Total
Carbon Column Observing Network (TCCON), the Greenhouse Gases Observing
Satellite (GOSAT), and the Orbiting Carbon Observatory (OCO-2). We find
that OCO-2 has high sensitivity to fluxes throughout the tropics and
Southern Hemisphere, while surface observations have high sensitivity to
fluxes in the northern extratropics throughout the year. For GOSAT
viewing modes, ocean glint data provide the strongest constraints on
fluxes in the tropics and Southern Hemisphere during Northern Hemisphere
fall and winter relative to other viewing modes. In contrast, GOSAT
nadir land data offer the greater sensitivity to fluxes in these regions
during Northern Hemisphere spring and summer. For OCO-2 viewing modes,
ocean glint data provided the dominant sensitivity to the surface fluxes
in the northern subtropics, tropics, and Southern Hemisphere. We
performed a series of inversion analyses using pseudodata and found that
the varying sensitivities can result in large differences in regional
flux estimates. However, combining measurements from different observing
systems to exploit their complementarity may lead to a posteriori flux
estimates with improved accuracy.
BibTeX:
@article{byrne17a,
  author = {Byrne, B. and Jones, D. B. A. and Strong, K. and Zeng, Z. -C. and Deng, F. and Liu, J.},
  title = {Sensitivity of CO2 surface flux constraints to observational coverage},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2017},
  volume = {122},
  number = {12},
  pages = {6672--6694},
  doi = {10.1002/2016JD026164}
}
Byrne B, Wunch D, Jones DBA, Strong K, Deng F, Baker I, Kohler P, Frankenberg C, Joiner J, Arora VK, Badawy B, Harper AB, Warneke T, Petri C, Kivi R and Roehl CM ({2018}), "Evaluating GPP and Respiration Estimates Over Northern Midlatitude Ecosystems Using Solar-Induced Fluorescence and Atmospheric CO2 Measurements", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., SEP, {2018}. Vol. {123}({9}), pp. {2976-2997}.
Abstract: On regional to global scales, few constraints exist on gross primary
productivity (GPP) and ecosystem respiration (R-e) fluxes. Yet
constraints on these fluxes are critical for evaluating and improving
terrestrial biosphere models. In this study, we evaluate the seasonal
cycle of GPP, R-e, and net ecosystem exchange (NEE) produced by four
terrestrial biosphere models and FLUXCOM, a data-driven model, over
northern midlatitude ecosystems. We evaluate the seasonal cycle of GPP
and NEE using solar-induced fluorescence retrieved from the Global Ozone
Monitoring Experiment-2 and column-averaged dry-air mole fractions of
CO2 (X-CO2) from the Total Carbon Column Observing Network,
respectively. We then infer R-e by combining constraints on GPP with
constraints on NEE from two flux inversions. An ensemble of optimized
R-e seasonal cycles is generated using five GPP estimates and two NEE
estimates. The optimized R-e curves generally show high consistency with
each other, with the largest differences due to the magnitude of GPP. We
find optimized R-e exhibits a systematically broader summer maximum than
modeled R-e, with values lower during June-July and higher during the
fall than R-e. Further analysis suggests that the differences could be
due to seasonal variations in the carbon use efficiency (possibly due to
an ecosystem-scale Kok effect) and to seasonal variations in the leaf
litter and fine root carbon pool. The results suggest that the inclusion
of variable carbon use efficiency for autotrophic respiration and carbon
pool dependence for heterotrophic respiration is important for
accurately simulating R-e.
BibTeX:
@article{byrne18a,
  author = {Byrne, B. and Wunch, D. and Jones, D. B. A. and Strong, K. and Deng, F. and Baker, I. and Kohler, P. and Frankenberg, C. and Joiner, J. and Arora, V. K. and Badawy, B. and Harper, A. B. and Warneke, T. and Petri, C. and Kivi, R. and Roehl, C. M.},
  title = {Evaluating GPP and Respiration Estimates Over Northern Midlatitude Ecosystems Using Solar-Induced Fluorescence and Atmospheric CO2 Measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2018},
  volume = {123},
  number = {9},
  pages = {2976-2997},
  doi = {{10.1029/2018JG004472}}
}
Carels N ({2011}), "The Challenge of Bioenergies: An Overview", In BIOFUEL'S ENGINEERING PROCESS TECHNOLOGY. , pp. 23-64. InTech.
BibTeX:
@incollection{carels11a,
  author = {Carels, Nicolas},
  editor = {Bernardes, MAD},
  title = {The Challenge of Bioenergies: An Overview},
  booktitle = {BIOFUEL'S ENGINEERING PROCESS TECHNOLOGY},
  publisher = {InTech},
  year = {2011},
  pages = {23--64}
}
Carouge C, Rayner PJ, Peylin P, Bousquet P, Chevallier F and Ciais P ({2010}), "What can we learn from European continuous atmospheric CO2 measurements to quantify regional fluxes - Part 2: Sensitivity of flux accuracy to inverse setup", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({6}), pp. 3119-3129.
Abstract: An inverse model using atmospheric CO2 observations from a European
network of stations to reconstruct daily CO2 fluxes and their
uncertainties over Europe at 50 km resolution has been developed within
a Bayesian framework. We use the pseudo-data approach in which we try to
recover known fluxes using a range of perturbations to the input. In
this study, the focus is put on the sensitivity of flux accuracy to the
inverse setup, varying the prior flux errors, the pseudo-data errors and
the network of stations. We show that, under a range of assumptions
about prior error and data error we can recover fluxes reliably at the
scale of 1000 km and 10 days. At smaller scales the performance is
highly sensitive to details of the inverse set-up. The use of temporal
correlations in the flux domain appears to be of the same importance as
the spatial correlations. We also note that the use of simple, isotropic
correlations on the prior flux errors is more reliable than the use of
apparently physically-based errors. Finally, increasing the European
atmospheric network density improves the area with significant error
reduction in the flux retrieval.
BibTeX:
@article{carouge10a,
  author = {Carouge, C. and Rayner, P. J. and Peylin, P. and Bousquet, P. and Chevallier, F. and Ciais, P.},
  title = {What can we learn from European continuous atmospheric CO2 measurements to quantify regional fluxes - Part 2: Sensitivity of flux accuracy to inverse setup},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {6},
  pages = {3119--3129},
  doi = {10.5194/acp-10-3119-2010}
}
Cervarich M, Shu S, Jain AK, Arneth A, Canadell J, Friedlingstein P, Houghton RA, Kato E, Koven C, Patra P, Poulter B, Sitch S, Stocker B, Viovy N, Wiltshire A and Zeng N ({2016}), "The terrestrial carbon budget of South and Southeast Asia", ENVIRONMENTAL RESEARCH LETTERS., OCT, {2016}. Vol. {11}({10})
Abstract: Accomplishing the objective of the current climate policies will require
establishing carbon budget and flux estimates in each region and county
of the globe by comparing and reconciling multiple estimates including
the observations and the results of top-down atmospheric carbon dioxide
(CO2) inversions and bottom-up dynamic global vegetation models. With
this in view, this study synthesizes the carbon source/sink due to net
ecosystem productivity (NEP), land cover land use change (E-LUC), fires
and fossil burning (E-FIRE) for the South Asia (SA), Southeast Asia
(SEA) and South and Southeast Asia (SSEA = SA + SEA) and each country in
these regions using the multiple top-down and bottom-up modeling
results. The terrestrial net biome productivity (NBP = NEP - E-LUC -
E-FIRE) calculated based on bottom-up models in combination with E-FIRE
based on GFED4s data show net carbon sinks of 217 +/- 147, 10 +/- 55,
and 227 +/- 279 TgC yr(-1) for SA, SEA, and SSEA. The top-down models
estimated NBP net carbon sinks were 20 +/- 170, 4 +/- 90 and 24 +/- 180
TgC yr(-1). In comparison, regional emissions from the combustion of
fossil fuels were 495, 275, and 770 TgC yr(-1), which are many times
higher than the NBP sink estimates, suggesting that the contribution of
the fossil fuel emissions to the carbon budget of SSEA results in a
significant net carbon source during the 2000s. When considering both
NBP and fossil fuel emissions for the individual countries within the
regions, Bhutan and Laos were net carbon sinks and rest of the countries
were net carbon source during the 2000s. The relative contributions of
each of the fluxes (NBP, NEP, ELUC, and EFIRE, fossil fuel emissions) to
a nation's net carbon flux varied greatly from country to country,
suggesting a heterogeneous dominant carbon fluxes on the country-level
throughout SSEA.
BibTeX:
@article{cervarich16a,
  author = {Cervarich, Matthew and Shu, Shijie and Jain, Atul K. and Arneth, Almut and Canadell, Josep and Friedlingstein, Pierre and Houghton, Richard A. and Kato, Etsushi and Koven, Charles and Patra, Prabir and Poulter, Ben and Sitch, Stephen and Stocker, Beni and Viovy, Nicolas and Wiltshire, Andy and Zeng, Ning},
  title = {The terrestrial carbon budget of South and Southeast Asia},
  journal = {ENVIRONMENTAL RESEARCH LETTERS},
  year = {2016},
  volume = {11},
  number = {10},
  doi = {10.1088/1748-9326/11/10/105006}
}
Chatterjee A, Michalak AM, Anderson JL, Mueller KL and Yadav V ({2012}), "Toward reliable ensemble Kalman filter estimates of CO2 fluxes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 28, {2012}. Vol. {117}
Abstract: The use of ensemble filters for estimating sources and sinks of carbon
dioxide (CO2) is becoming increasingly common, because they provide a
relatively computationally efficient framework for assimilating
high-density observations of CO2. Their applicability for estimating
fluxes at high-resolutions and the equivalence of their estimates to
those from more traditional ``batch'' inversion methods have not been
demonstrated, however. In this study, we introduce a Geostatistical
Ensemble Square Root Filter (GEnSRF) as a prototypical filter and
examine its performance using a synthetic data study over North America
at a high spatial (1 degrees x 1 degrees) and temporal (3-hourly)
resolution. The ensemble performance, both in terms of estimates and
associated uncertainties, is benchmarked against a batch inverse
modeling setup in order to isolate and quantify the degradation in the
estimates due to the numerical approximations and parameter choices in
the ensemble filter. The examined case studies demonstrate that adopting
state-of-the-art covariance inflation and localization schemes is a
necessary but not sufficient condition for ensuring good filter
performance, as defined by its ability to yield reliable flux estimates
and uncertainties across a range of resolutions. Observational density
is found to be another critical factor for stabilizing the ensemble
performance, which is attributed to the lack of a dynamical model for
evolving the ensemble between assimilation times. This and other results
point to key differences between the applicability of ensemble
approaches to carbon cycle science relative to its use in meteorological
applications where these tools were originally developed.
BibTeX:
@article{chatterjee12a,
  author = {Chatterjee, Abhishek and Michalak, Anna M. and Anderson, Jeffrey L. and Mueller, Kim L. and Yadav, Vineet},
  title = {Toward reliable ensemble Kalman filter estimates of CO2 fluxes},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2012JD018176}
}
Chatterjee A (2012), "Data Assimilation for Atmospheric CO2: Towards Improved Estimates of CO2 Concentrations and Fluxes.". Thesis at: University of Michigan.
BibTeX:
@phdthesis{chatterjee12b,
  author = {A Chatterjee},
  title = {Data Assimilation for Atmospheric CO2: Towards Improved Estimates of CO2 Concentrations and Fluxes.},
  school = {University of Michigan},
  year = {2012},
  url = {https://deepblue.lib.umich.edu/handle/2027.42/96172}
}
Checa-Garcia R, Landgraf J, Galli A, Hase F, Velazco VA, Tran H, Boudon V, Alkemade F and Butz A ({2015}), "Mapping spectroscopic uncertainties into prospective methane retrieval errors from Sentinel-5 and its precursor", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({9}), pp. 3617-3629.
Abstract: Sentinel-5 (S5) and its precursor (S5P) are future European satellite
missions aiming at global monitoring of methane (CH4) column-average dry
air mole fractions (XCH4). The spectrometers to be deployed onboard the
satellites record spectra of sunlight backscattered from the Earth's
surface and atmosphere. In particular, they exploit CH4 absorption in
the shortwave infrared spectral range around 1.65 mu m (S5 only) and
2.35 mu m (both S5 and S5P) wavelength. Given an accuracy goal of better
than 2% for XCH4 to be delivered on regional scales, assessment and
reduction of potential sources of systematic error such as spectroscopic
uncertainties is crucial. Here, we investigate how spectroscopic errors
propagate into retrieval errors on the global scale. To this end,
absorption spectra of a ground-based Fourier transform spectrometer
(FTS) operating at very high spectral resolution serve as estimate for
the quality of the spectroscopic parameters. Feeding the FTS fitting
residuals as a perturbation into a global ensemble of simulated S5- and
S5P-like spectra at relatively low spectral resolution, XCH4 retrieval
errors exceed 0.6% in large parts of the world and show systematic
correlations on regional scales, calling for improved spectroscopic
parameters.
BibTeX:
@article{checa-garcia15a,
  author = {Checa-Garcia, R. and Landgraf, J. and Galli, A. and Hase, F. and Velazco, V. A. and Tran, H. and Boudon, V. and Alkemade, F. and Butz, A.},
  title = {Mapping spectroscopic uncertainties into prospective methane retrieval errors from Sentinel-5 and its precursor},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {9},
  pages = {3617--3629},
  doi = {10.5194/amt-8-3617-2015}
}
Chen B and Coops NC ({2009}), "Understanding of Coupled Terrestrial Carbon, Nitrogen and Water Dynamics-An Overview", SENSORS., NOV, {2009}. Vol. {9}({11}), pp. 8624-8657.
Abstract: Coupled terrestrial carbon (C), nitrogen (N) and hydrological processes
play a crucial role in the climate system, providing both positive and
negative feedbacks to climate change. In this review we summarize
published research results to gain an increased understanding of the
dynamics between vegetation and atmosphere processes. A variety of
methods, including monitoring (e. g., eddy covariance flux tower, remote
sensing, etc.) and modeling (i.e., ecosystem, hydrology and atmospheric
inversion modeling) the terrestrial carbon and water budgeting, are
evaluated and compared. We highlight two major research areas where
additional research could be focused: (i) Conceptually, the hydrological
and biogeochemical processes are closely linked, however, the coupling
processes between terrestrial C, N and hydrological processes are far
from well understood; and (ii) there are significant uncertainties in
estimates of the components of the C balance, especially at landscape
and regional scales. To address these two questions, a synthetic
research framework is needed which includes both bottom-up and top-down
approaches integrating scalable (footprint and ecosystem) models and a
spatially nested hierarchy of observations which include multispectral
remote sensing, inventories, existing regional clusters of
eddy-covariance flux towers and CO2 mixing ratio towers and chambers.
BibTeX:
@article{chen09a,
  author = {Chen, Baozhang and Coops, Nicholas C.},
  title = {Understanding of Coupled Terrestrial Carbon, Nitrogen and Water Dynamics-An Overview},
  journal = {SENSORS},
  year = {2009},
  volume = {9},
  number = {11},
  pages = {8624--8657},
  doi = {10.3390/s91108624}
}
Chen H, Winderlich J, Gerbig C, Katrynski K, Jordan A and Heimann M ({2012}), "Validation of routine continuous airborne CO2 observations near the Bialystok Tall Tower", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({4}), pp. 873-889.
Abstract: Since 2002 in situ airborne measurements of atmospheric CO2 mixing
ratios have been performed regularly aboard a rental aircraft near
Bialystok (53A degrees 08A ` N, 23A degrees 09A ` E), a city in
northeastern Poland. Since August 2008, the in situ CO2 measurements
have been made by a modified commercially available and fully automated
non-dispersive infrared (NDIR) analyzer system. The response of the
analyzer has been characterized and the CO2 mixing ratio stability of
the associated calibration system has been fully tested, which results
in an optimal calibration strategy and allows for an accuracy of the CO2
measurements within 0.2 ppm. Besides the in situ measurements, air
samples have been collected in glass flasks and analyzed in the
laboratory for CO2 and other trace gases. To validate the in situ CO2
measurements against reliable discrete flask measurements, we developed
weighting functions that mimic the temporal averaging of the flask
sampling process. Comparisons between in situ and flask CO2 measurements
demonstrate that these weighting functions can compensate for
atmospheric variability, and provide an effective method for validating
airborne in situ CO2 measurements. In addition, we show the nine-year
records of flask CO2 measurements. The new system, automated since
August 2008, has eliminated the need for manual in-flight calibrations,
and thus enables an additional vertical profile, 20 km away, to be
sampled at no additional cost in terms of flight hours. This sampling
strategy provides an opportunity to investigate both temporal and
spatial variability on a regular basis.
BibTeX:
@article{chen12a,
  author = {Chen, H. and Winderlich, J. and Gerbig, C. and Katrynski, K. and Jordan, A. and Heimann, M.},
  title = {Validation of routine continuous airborne CO2 observations near the Bialystok Tall Tower},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2012},
  volume = {5},
  number = {4},
  pages = {873--889},
  doi = {10.5194/amt-5-873-2012}
}
Chen B (2012), "Towards an understanding of coupled carbon, water and nitrogen dynamics at sand, landscape and regional scales". Thesis at: THE UNIVERSITY OF BRITISH COLUMBIA.
BibTeX:
@phdthesis{chen12b,
  author = {B Chen},
  title = {Towards an understanding of coupled carbon, water and nitrogen dynamics at sand, landscape and regional scales},
  school = {THE UNIVERSITY OF BRITISH COLUMBIA},
  year = {2012},
  url = {https://open.library.ubc.ca/collections/ubctheses/24/items/1.0103459}
}
Chen B, Zhang H, Coops NC, Fu D, Worthy DEJ, Xu G and Black TA ({2014}), "Assessing scalar concentration footprint climatology and land surface impacts on tall-tower CO2 concentration measurements in the boreal forest of central Saskatchewan, Canada", THEORETICAL AND APPLIED CLIMATOLOGY., OCT, {2014}. Vol. {118}({1-2}), pp. 115-132.
Abstract: Reducing the large uncertainties in current estimates of CO2 sources and
sinks at regional scales (10(2)-10(5) km(2)) is fundamental to improving
our understanding of the terrestrial carbon cycle. Continuous
high-precision CO2 concentration measurements on a tower within the
planetary boundary layer contain information on regional carbon fluxes;
however, its spatial representativeness is generally unknown. In this
study, we developed a footprint model (Simple Analytical Footprint model
based on Eulerian coordinates for scalar Concentration [SAFE-C]) and
applied it to two CO2 concentration towers in central Canada: the East
Trout Lake 106-m-tall tower (54A degrees 21'N, 104A degrees 59'W) and
the Candle Lake 28-m-high tower (53A degrees 59'N, 105A degrees 07'W).
Results show that the ETL tower's annual concentration footprints were
around 10(3)-10(5) km(2). The monthly footprint climatologies in summer
were 1.5-2 times larger than in winter. The impacts of land surface
carbon flux associated with heterogeneous distribution of vegetation
types on the CO2 concentration measurements were different for the
different heights, varied with a range of +/- 5 % to +/- 10 % among
four heights. This study indicates that concentration footprint
climatology analysis is important in interpreting the seasonal, annual
and inter-annual variations of tower measured CO2 concentration data and
is essential for comparing and scaling regional carbon flux estimates
using top-down or bottom-up approaches.
BibTeX:
@article{chen14a,
  author = {Chen, Baozhang and Zhang, Huifang and Coops, Nicholas C. and Fu, Dongjie and Worthy, Douglas E. J. and Xu, Guang and Black, T. Andy},
  title = {Assessing scalar concentration footprint climatology and land surface impacts on tall-tower CO2 concentration measurements in the boreal forest of central Saskatchewan, Canada},
  journal = {THEORETICAL AND APPLIED CLIMATOLOGY},
  year = {2014},
  volume = {118},
  number = {1-2},
  pages = {115--132},
  doi = {10.1007/s00704-013-1038-2}
}
Chen JM, Fung JW, Mo G, Deng F and West TO ({2015}), "Atmospheric inversion of surface carbon flux with consideration of the spatial distribution of US crop production and consumption", BIOGEOSCIENCES. Vol. {12}({2}), pp. 323-343.
Abstract: In order to improve quantification of the spatial distribution of carbon
sinks and sources in the conterminous US, we conduct a nested global
atmospheric inversion with detailed spatial information on crop
production and consumption. County-level cropland net primary
productivity, harvested biomass, soil carbon change, and human and
livestock consumption data over the conterminous US are used for this
purpose. Time-dependent Bayesian synthesis inversions are conducted
based on CO2 observations at 210 stations to infer CO2 fluxes globally
at monthly time steps with a nested focus on 30 regions in North
America. Prior land surface carbon fluxes are first generated using a
bio-spheric model, and the inversions are constrained using prior fluxes
with and without adjustments for crop production and consumption over
the 2002-2007 period. After these adjustments, the inverted regional
carbon sink in the US Midwest increases from 0.25 +/- 0.03 to 0.42 +/-
0.13 PgC yr(-1), whereas the large sink in the US southeast forest
region is weakened from 0.41 +/- 0.12 to 0.29 +/- 0.12 PgC yr(-1). These
adjustments also reduce the inverted sink in the west region from 0.066
+/- 0.04 to 0.040 +/- 0.02 PgC yr(-1) because of high crop consumption
and respiration by humans and livestock. The general pattern of sink
increases in crop production areas and sink decreases (or source
increases) in crop consumption areas highlights the importance of
considering the lateral carbon transfer in crop products in atmospheric
inverse modeling, which provides a reliable atmospheric perspective of
the overall carbon balance at the continental scale but is unreliable
for separating fluxes from different ecosystems.
BibTeX:
@article{chen15a,
  author = {Chen, J. M. and Fung, J. W. and Mo, G. and Deng, F. and West, T. O.},
  title = {Atmospheric inversion of surface carbon flux with consideration of the spatial distribution of US crop production and consumption},
  journal = {BIOGEOSCIENCES},
  year = {2015},
  volume = {12},
  number = {2},
  pages = {323--343},
  doi = {10.5194/bg-12-323-2015}
}
Chen M (2016), "Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems". Thesis at: UNIVERSITY OF MINNESOTA.
BibTeX:
@phdthesis{chen16a,
  author = {M Chen},
  title = {Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems},
  school = {UNIVERSITY OF MINNESOTA},
  year = {2016},
  url = {http://search.proquest.com/openview/4e5113263c4ca244a5b38a8271693056/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Chen Z, Chen JM, Zhang S, Zheng X, Ju W, Mo G and Lu X (2016), "Optimization of terrestrial ecosystem model parameters using atmospheric CO2 concentration data with the Global Carbon Assimilation System (GCAS)", Journal of Geophysical Research: Biogeosciences. Vol. 122(12), pp. 3218-3237. Wiley Online Library.
BibTeX:
@article{chen16b,
  author = {Chen, Zhuoqi and Chen, Jing M and Zhang, Shupeng and Zheng, Xiaogu and Ju, Weiming and Mo, Gang and Lu, Xiaoliang},
  title = {Optimization of terrestrial ecosystem model parameters using atmospheric CO2 concentration data with the Global Carbon Assimilation System (GCAS)},
  journal = {Journal of Geophysical Research: Biogeosciences},
  publisher = {Wiley Online Library},
  year = {2016},
  volume = {122},
  number = {12},
  pages = {3218--3237},
  doi = {10.1002/2016JG003716/full}
}
Chen JM, Mo G and Deng F ({2017}), "A joint global carbon inversion system using both CO2 and (CO2)-C-13 atmospheric concentration data", GEOSCIENTIFIC MODEL DEVELOPMENT., MAR 16, {2017}. Vol. {10}({3}), pp. 1131-1156.
Abstract: Observations of (CO2)-C-13 at 73 sites compiled in the GLOBALVIEW
database are used for an additional constraint in a global atmospheric
inversion of the surface CO2 flux using CO2 observations at 210 sites
(62 collocated with (CO2)-C-13 sites) for the 2002-2004 period for 39
land regions and 11 ocean regions. This constraint is implemented using
prior CO2 fluxes estimated with a terrestrial ecosystem model and an
ocean model. These models simulate (CO2)-C-13 discrimination rates of
terrestrial photosynthesis and oceanatmosphere diffusion processes. In
both models, the (CO2)-C-13 disequilibrium between fluxes to and from
the atmosphere is considered due to the historical change in atmospheric
(CO2)-C-13 concentration. This joint inversion system using
both(13)CO(2) and CO2 observations is effectively a double deconvolution
system with consideration of the spatial variations of isotopic
discrimination and disequilibrium. Compared to the CO2-only inversion,
this (CO2)-C-13 constraint on the inversion considerably reduces the
total land carbon sink from 3.40 +/- 0.84 to 2.53 +/- 0.93 Pg Cyear 1
but increases the total oceanic carbon sink from 1.48 +/- 0.40 to 2.36
+/- 0.49 Pg C year 1. This constraint also changes the spatial
distribution of the carbon sink. The largest sink increase occurs in the
Amazon, while the largest source increases are in southern Africa, and
Asia, where CO2 data are sparse. Through a case study, in which the
spatial distribution of the annual (CO2)-C-13 discrimination rate over
land is ignored by treating it as a constant at the global average of 14
: 1 the spatial distribution of the inverted CO2 flux over land was
found to be significantly modified (up to 15% for some regions). The
uncertainties in our disequilibrium flux estimation are 8.0 and 12.7 Pg
C year 1% for land and ocean, respectively. These uncertainties induced
the unpredictability of 0.47 and 0.54 Pg Cyear(-1) in the inverted CO2
fluxes for land and ocean, respectively. Our joint inversion system is
therefore useful for improving the partitioning between ocean and land
sinks and the spatial distribution of the inverted carbon flux.
BibTeX:
@article{chen17a,
  author = {Chen, Jing M. and Mo, Gang and Deng, Feng},
  title = {A joint global carbon inversion system using both CO2 and (CO2)-C-13 atmospheric concentration data},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2017},
  volume = {10},
  number = {3},
  pages = {1131--1156},
  doi = {10.5194/gmd-10-1131-2017}
}
Cheng Y, An X, Yun F, Zhou L, Liu L, Fang S and Xu L (2013), "Simulation of CO2 variations at Chinese background atmospheric monitoring stations between 2000 and 2009: Applying a CarbonTracker model", Chin. Sci. Bull. Vol. 58(32), pp. 3986-3993.
BibTeX:
@article{cheng13a,
  author = {Cheng, Y and An, X and Yun, F and Zhou, L and Liu, L and Fang, S and Xu, Lin},
  title = {Simulation of CO2 variations at Chinese background atmospheric monitoring stations between 2000 and 2009: Applying a CarbonTracker model},
  journal = {Chin. Sci. Bull},
  year = {2013},
  volume = {58},
  number = {32},
  pages = {3986--3993}
}
Cheng S, An X, Zhou L, Liu L, Fang S, Yao B and Liu Z (2015), "CO2 concentration representation of source and sink area at Shangdianzi atmospheric background station in Beijing", China Environmental Science.
BibTeX:
@article{cheng15a,
  author = {Cheng, Siyang and An, Xingqin and Zhou, Lingxi and Liu, LiXin and Fang, Shuangxi and Yao, Bo and Liu, Zhao},
  title = {CO2 concentration representation of source and sink area at Shangdianzi atmospheric background station in Beijing},
  journal = {China Environmental Science},
  year = {2015},
  url = {http://or.nsfc.gov.cn/bitstream/00001903-5/261235/1/1000014841151.pdf}
}
Cheng S, An X, Zhou L, Tans PP and Jacobson A ({2017}), "Atmospheric CO2 at Waliguan station in China: Transport climatology, temporal patterns and source-sink region representativeness", ATMOSPHERIC ENVIRONMENT., JUN, {2017}. Vol. {159}, pp. 107-116.
Abstract: In order to explore where the source and sink have the greatest impact
on CO2 background concentration at Waliguan (WLG) station, a statistical
method is here proposed to calculate the representative source sink
region. The key to this method is to find the best footprint threshold,
and the study is carried out in four parts. Firstly, transport
climatology, expressed by total monthly footprint, was simulated by FLEX
PART on a 7-day time scale. Surface CO2 emissions in Eurasia frequently
transported to WLG station. WLG station was mainly influenced by the
westerlies in winter and partly controlled by the Southeast Asian
monsoon in summer. Secondly, CO2 concentrations, simulated by CT2015,
were processed and analyzed through data quality control, screening,
fitting and comparing. CO2 concentrations displayed obvious seasonal
variation, with the maximum and minimum concentration appearing in April
and August, respectively. The correlation of CO2 fitting background
concentrations was R-2 = 0.91 between simulation and observation. The
temporal patterns were mainly correlated with CO2 exchange of biosphere
atmosphere, human activities and air transport. Thirdly, for the monthly
CO2 fitting background concentrations from CT2015, a best footprint
threshold was found based on correlation analysis and numerical
iteration using the data of footprints and emissions. The grid cells
where monthly footprints were greater than the best footprint threshold
were the best threshold area corresponding to representative source-sink
region. The representative source-sink region of maximum CO2
concentration in April was primarily located in Qinghai province, but
the minimum CO2 concentration in August was mainly influenced by
emissions in a wider region. Finally, we briefly presented the CO2
source-sink characteristics in the best threshold area. Generally, the
best threshold area was a carbon sink. The major source and sink were
relatively weak owing to less human activities and vegetation types in
this high altitude area. CO2 concentrations were more influenced by
human activities when air mass passed through many urban areas in
summer. Therefore, the combination of footprints and emissions is an
effective approach for assessing the source-sink region
representativeness of CO2 background concentration. (C) 2017 Elsevier
Ltd. All rights reserved.
BibTeX:
@article{cheng17a,
  author = {Cheng, Siyang and An, Xingqin and Zhou, Lingxi and Tans, Pieter P. and Jacobson, Andy},
  title = {Atmospheric CO2 at Waliguan station in China: Transport climatology, temporal patterns and source-sink region representativeness},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2017},
  volume = {159},
  pages = {107--116},
  doi = {10.1016/j.atmosenv.2017.03.055}
}
Cheng H, Mi Z, Wei X, Yong-wei W, Wei W, Griffis T, Shou-dong L and Xu-hui L (2017), "Effect of Flux and its Uncertainty on Tall Tower CO2 Concentration Simulation in the Agricultural Domain", 中国农业气象 (Chinese Journal of Agrometeorology).
BibTeX:
@article{cheng17b,
  author = {Hu Cheng and Zhang Mi and Xiao Wei and Wang Yong-wei and Wang Wei and Tim Griffis and Liu Shou-dong and Li Xu-hui},
  title = {Effect of Flux and its Uncertainty on Tall Tower CO2 Concentration Simulation in the Agricultural Domain},
  journal = {中国农业气象 (Chinese Journal of Agrometeorology)},
  year = {2017},
  url = {https://yncenter.sites.yale.edu/sites/default/files/files/hu_cheng_2017-2.pdf}
}
Cheng H, Mi Z, Wei X, Yong-wei W, Wei W, Griffis T, Shou-dong L and Xu-hui L (2017), "Tall tower CO2 concentration simulation using the WRF-STILT model", China Environmental Science. Vol. 37(7), pp. 2424-24-37.
BibTeX:
@article{cheng17c,
  author = {Hu Cheng and Zhang Mi and Xiao Wei and Wang Yong-wei and Wang Wei and Tim Griffis and Liu Shou-dong and Li Xu-hui},
  title = {Tall tower CO2 concentration simulation using the WRF-STILT model},
  journal = {China Environmental Science},
  year = {2017},
  volume = {37},
  number = {7},
  pages = {2424-24-37},
  url = {http://manu36.magtech.com.cn/Jweb_zghjkx/CN/article/downloadArticleFile.do?attachType=PDF&id=15218}
}
Cheng H, Shoudong L, Chang C, Jingzheng X, Zhengda C, Wengian L, Jiaping X, mi Z, Wei X and Xuhui L (2017), "Simulation of atmospheric CO2 concentration and source apportionment analysis in Nanjing City", Acta Scientiae Circumstantiae., OCT, 2017. Vol. 37(10), pp. 3862-3875.
BibTeX:
@article{cheng17d,
  author = {Hu Cheng and Liu Shoudong and Cao Chang and Xu Jingzheng and Cao Zhengda and Li Wengian and Xu Jiaping and Zhang mi and Xiao Wei and Li Xuhui},
  title = {Simulation of atmospheric CO2 concentration and source apportionment analysis in Nanjing City},
  journal = {Acta Scientiae Circumstantiae},
  year = {2017},
  volume = {37},
  number = {10},
  pages = {3862-3875},
  url = {http://html.rhhz.net/hjkxxb/html/20170224004.htm}
}
Cheng S, Zhou L, Tans PP, An X and Liu Y ({2018}), "Comparison of atmospheric CO2 mole fractions and source sink characteristics at four WMO/GAW stations in China", ATMOSPHERIC ENVIRONMENT., MAY, {2018}. Vol. {180}, pp. {216-225}.
Abstract: As CO2 is a primary driving factor of climate change, the mole fraction
and source-sink characteristics of atmospheric CO2 over China are
constantly inferred from multi-source and multi-site data. In this
paper, we compared ground-based CO2 measurements with satellite
retrievals and investigated the source-sink regional representativeness
at China's four WMO/GAW stations. The results indicate that, firstly,
atmospheric CO2 mole fractions from ground-based sampling measurement
and Greenhouse Gases Observing Satellite (GOSAT) products reveal similar
seasonal variation. The seasonal amplitude of the column-averaged CO2
mole fractions is smaller than that of the ground-based CO2 at all
stations. The extrema of the seasonal cycle of ground-based and column
CO2 mole fractions are basically synchronous except a slight phase delay
at Lin'an (LAN) station. For the two-year average, the column CO2 is
lower than ground-based CO2, and both of them reveal the lowest CO2 mole
fraction at Waliguan (WLG) station. The lowest (similar to 4 ppm) and
largest (similar to 8 ppm) differences between the column and
ground-based CO2 appear at WLG and Longfengshan (LFS) stations,
respectively. The CO2 mole fraction and its difference between GOSAT and
ground-based measurement are smaller in summer than in winter. The
differences of summer column CO2 among these stations are also much
smaller than their ground-based counterparts. In winter, the maximum of
ground-based CO2 mole fractions and the greatest difference between the
two (ground-based and column) datasets appear at the LFS station.
Secondly, the representative areas of the monthly CO2 background mole
fractions at each station were found by employing footprints and
emissions. Smaller representative areas appeared at Shangdianzi (SDZ)
and LFS, whereas larger ones were seen at WLG and LAN. The
representative areas in summer are larger than those in winter at WLG
and SDZ, but the situation is opposite at LAN and LFS. The
representative areas for the stations are different in summer and
winter, distributed in four typical regions. The CO2 net fluxes in these
representative areas show obvious seasonal cycles with similar trends
but different varying ranges and different time of the strongest sink.
The intensities and uncertainties of the CO2 fluxes are different at
different stations in different months and source-sink sectors. Overall,
the WLG station is almost a carbon sink, but the other three stations
present stronger carbon sources for most of the year. These findings
could be conducive to the application of multi-source CO2 data and the
understanding of regional CO2 source-sink characteristics and patterns
over China.
BibTeX:
@article{cheng18a,
  author = {Cheng, Siyang and Zhou, Lingxi and Tans, Pieter P. and An, Xingqin and Liu, Yunsong},
  title = {Comparison of atmospheric CO2 mole fractions and source sink characteristics at four WMO/GAW stations in China},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2018},
  volume = {180},
  pages = {216-225},
  doi = {{10.1016/j.atmosenv.2018.03.010}}
}
Chevallier F, Engelen RJ, Carouge C, Conway TJ, Peylin P, Pickett-Heaps C, Ramonet M, Rayner PJ and Xueref-Remy I ({2009}), "AIRS-based versus flask-based estimation of carbon surface fluxes", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 23, {2009}. Vol. {114}
Abstract: This paper demonstrates an inversion of surface CO2 fluxes using
concentrations derived from assimilation of satellite radiances.
Radiances come from the Atmospheric Infrared Sounder (AIRS) and are
assimilated within the system of the European Centre for Medium-Range
Weather Forecasts. We evaluate the quality of the inverted fluxes by
comparing simulated concentrations with independent airborne
measurements. As a benchmark we use an inversion based on surface flask
measurements and another using only the global concentration trend. We
show that the AIRS-based inversion is able to improve the match to the
independent data compared to the prior estimate but that it usually
performs worse than either the flask-based or trend-based inversion.
BibTeX:
@article{chevallier09a,
  author = {Chevallier, Frederic and Engelen, Richard J. and Carouge, Claire and Conway, Thomas J. and Peylin, Philippe and Pickett-Heaps, Christopher and Ramonet, Michel and Rayner, Peter J. and Xueref-Remy, Irene},
  title = {AIRS-based versus flask-based estimation of carbon surface fluxes},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2009},
  volume = {114},
  doi = {10.1029/2009JD012311}
}
Chevallier F, Ciais P, Conway TJ, Aalto T, Anderson BE, Bousquet P, Brunke EG, Ciattaglia L, Esaki Y, Froehlich M, Gomez A, Gomez-Pelaez AJ, Haszpra L, Krummel PB, Langenfelds RL, Leuenberger M, Machida T, Maignan F, Matsueda H, Morgui JA, Mukai H, Nakazawa T, Peylin P, Ramonet M, Rivier L, Sawa Y, Schmidt M, Steele LP, Vay SA, Vermeulen AT, Wofsy S and Worthy D ({2010}), "CO2 surface fluxes at grid point scale estimated from a global 21 year reanalysis of atmospheric measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 9, {2010}. Vol. {115}
Abstract: This paper documents a global Bayesian variational inversion of CO2
surface fluxes during the period 1988-2008. Weekly fluxes are estimated
on a 3.75 degrees x 2.5 degrees (longitude-latitude) grid throughout the
21 years. The assimilated observations include 128 station records from
three large data sets of surface CO2 mixing ratio measurements. A Monte
Carlo approach rigorously quantifies the theoretical uncertainty of the
inverted fluxes at various space and time scales, which is particularly
important for proper interpretation of the inverted fluxes. Fluxes are
evaluated indirectly against two independent CO2 vertical profile data
sets constructed from aircraft measurements in the boundary layer and in
the free troposphere. The skill of the inversion is evaluated by the
improvement brought over a simple benchmark flux estimation based on the
observed atmospheric growth rate. Our error analysis indicates that the
carbon budget from the inversion should be more accurate than the a
priori carbon budget by 20% to 60% for terrestrial fluxes aggregated
at the scale of subcontinental regions in the Northern Hemisphere and
over a year, but the inversion cannot clearly distinguish between the
regional carbon budgets within a continent. On the basis of the
independent observations, the inversion is seen to improve the fluxes
compared to the benchmark: the atmospheric simulation of CO2 with the
Bayesian inversion method is better by about 1 ppm than the benchmark in
the free troposphere, despite possible systematic transport errors. The
inversion achieves this improvement by changing the regional fluxes over
land at the seasonal and at the interannual time scales.
BibTeX:
@article{chevallier10a,
  author = {Chevallier, F. and Ciais, P. and Conway, T. J. and Aalto, T. and Anderson, B. E. and Bousquet, P. and Brunke, E. G. and Ciattaglia, L. and Esaki, Y. and Froehlich, M. and Gomez, A. and Gomez-Pelaez, A. J. and Haszpra, L. and Krummel, P. B. and Langenfelds, R. L. and Leuenberger, M. and Machida, T. and Maignan, F. and Matsueda, H. and Morgui, J. A. and Mukai, H. and Nakazawa, T. and Peylin, P. and Ramonet, M. and Rivier, L. and Sawa, Y. and Schmidt, M. and Steele, L. P. and Vay, S. A. and Vermeulen, A. T. and Wofsy, S. and Worthy, D.},
  title = {CO2 surface fluxes at grid point scale estimated from a global 21 year reanalysis of atmospheric measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2010},
  volume = {115},
  doi = {10.1029/2010JD013887}
}
Chevallier F, Wang T, Ciais P, Maignan F, Bocquet M, Arain MA, Cescatti A, Chen J, Dolman AJ, Law BE, Margolis HA, Montagnani L and Moors EJ ({2012}), "What eddy-covariance measurements tell us about prior land flux errors in CO2-flux inversion schemes", GLOBAL BIOGEOCHEMICAL CYCLES., MAR 10, {2012}. Vol. {26}
Abstract: To guide the future development of CO2-atmospheric inversion modeling
systems, we analyzed the errors arising from prior information about
terrestrial ecosystem fluxes. We compared the surface fluxes calculated
by a process-based terrestrial ecosystem model with daily averages of
CO2 flux measurements at 156 sites across the world in the FLUXNET
network. At the daily scale, the standard deviation of the model-data
fit was 2.5 gC.m(2).d(-1); temporal autocorrelations were significant at
the weekly scale (>0.3 for lags less than four weeks), while spatial
correlations were confined to within the first few hundred kilometers
(<0.2 after 200 km). Separating out the plant functional types did not
increase the spatial correlations, except for the deciduous broad-leaved
forests. Using the statistics of the flux measurements as a proxy for
the statistics of the prior flux errors was shown not to be a viable
approach. A statistical model allowed us to upscale the site-level flux
error statistics to the coarser spatial and temporal resolutions used in
regional or global models. This approach allowed us to quantify how
aggregation reduces error variances, while increasing correlations. As
an example, for a typical inversion of grid point (300 km x 300 km)
monthly fluxes, we found that the prior flux error follows an
approximate e-folding correlation length of 500 km only, with
correlations from one month to the next as large as 0.6.
BibTeX:
@article{chevallier12a,
  author = {Chevallier, Frederic and Wang, Tao and Ciais, Philippe and Maignan, Fabienne and Bocquet, Marc and Arain, M. Altaf and Cescatti, Alessandro and Chen, Jiquan and Dolman, A. Johannes and Law, Beverly E. and Margolis, Hank A. and Montagnani, Leonardo and Moors, Eddy J.},
  title = {What eddy-covariance measurements tell us about prior land flux errors in CO2-flux inversion schemes},
  journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
  year = {2012},
  volume = {26},
  doi = {10.1029/2010GB003974}
}
Chevallier F and O'Dell CW ({2013}), "Error statistics of Bayesian CO2 flux inversion schemes as seen from GOSAT", GEOPHYSICAL RESEARCH LETTERS., MAR 28, {2013}. Vol. {40}({6}), pp. 1252-1256.
Abstract: Statistical modeling is at the root of CO2 atmospheric inversion
systems, but few studies have focused on the quality of their assigned
probability distributions. In this paper, we assess the reliability of
the error models that are in input and in output of a specific CO2
atmospheric inversion system when it assimilates surface air sample
measurements. We confront these error models with the mismatch between
4D simulations of CO2 and independent satellite retrievals of the total
CO2 column. Taking all sources of uncertainties into account, it is
shown that both prior and posterior errors are consistent with the
actual departures, to the point that the theoretical error reduction
brought by the surface measurements on the simulation of the Greenhouse
gases Observing SATellite (GOSAT) total column measurements (15
corresponds to the actual reduction seen over the midlatitude and
tropical lands and over the tropical oceans.
BibTeX:
@article{chevallier13a,
  author = {Chevallier, Frederic and O'Dell, Christopher W.},
  title = {Error statistics of Bayesian CO2 flux inversion schemes as seen from GOSAT},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2013},
  volume = {40},
  number = {6},
  pages = {1252--1256},
  doi = {10.1002/grl.50228}
}
Chevallier F ({2013}), "On the parallelization of atmospheric inversions of CO2 surface fluxes within a variational framework", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {6}({3}), pp. 783-790.
Abstract: The variational formulation of Bayes' theorem allows inferring CO2
sources and sinks from atmospheric concentrations at much higher
time-space resolution than the ensemble or analytical approaches.
However, it usually exhibits limited scalable parallelism. This
limitation hinders global atmospheric inversions operated on decadal
time scales and regional ones with kilometric spatial scales because of
the computational cost of the underlying transport model that has to be
run at each iteration of the variational minimization. Here, we
introduce a physical parallelization (PP) of variational atmospheric
inversions. In the PP, the inversion still manages a single physically
and statistically consistent window, but the transport model is run in
parallel overlapping sub-segments in order to massively reduce the
computation wall-clock time of the inversion. For global inversions, a
simplification of transport modelling is described to connect the output
of all segments. We demonstrate the performance of the approach on a
global inversion for CO2 with a 32 yr inversion window (1979-2010) with
atmospheric measurements from 81 sites of the NOAA global cooperative
air sampling network. In this case, we show that the duration of the
inversion is reduced by a seven-fold factor (from months to days), while
still processing the three decades consistently and with improved
numerical stability.
BibTeX:
@article{chevallier13b,
  author = {Chevallier, F.},
  title = {On the parallelization of atmospheric inversions of CO2 surface fluxes within a variational framework},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2013},
  volume = {6},
  number = {3},
  pages = {783--790},
  doi = {10.5194/gmd-6-783-2013}
}
Chevallier F (2013), "Report on the quality of the inverted CO2 fluxes", MACC-II delivrable D. Vol. 43
BibTeX:
@article{chevallier13c,
  author = {F Chevallier},
  title = {Report on the quality of the inverted CO2 fluxes},
  journal = {MACC-II delivrable D},
  year = {2013},
  volume = {43},
  url = {https://www-gmes-atmosphere-eu.ecmwf.int/documents/maccii/deliverables/ghg/MACCII_GHG_DEL_D43.4_20120430_Chevallier.pdf}
}
Ciais P, Canadell JG, Luyssaert S, Chevallier F, Shvidenko A, Poussi Z, Jonas M, Peylin P, King AW, Schulze E-D, Piao S, Roedenbeck C, Peters W and Breon F-M ({2010}), "Can we reconcile atmospheric estimates of the Northern terrestrial carbon sink with land-based accounting?", CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY., OCT, {2010}. Vol. {2}({4}), pp. 225-230.
Abstract: We estimate the northern hemisphere (NH) terrestrial carbon sink by
comparing four recent atmospheric inversions with land-based C
accounting data for six large northern regions. The mean NH terrestrial
CO2 sink from the inversion models is 1.7 Pg C year(-1) over the period
2000-2004. The uncertainty of this estimate is based on the typical
individual (1-sigma) precision of one inversion (0.9 Pg C year(-1)) and
is consistent with the min-max range of the four inversion mean
estimates (0.8 Pg C year(-1)). Inversions agree within their uncertainty
for the distribution of the NH sink of CO2 in longitude, with Russia
being the largest sink. The land-based accounting estimate of NH carbon
sink is 1.7 Pg C year(-1) for the sum of the six regions studied. The
1-sigma uncertainty of the land-based estimate (0.3 Pg C year(-1)) is
smaller than that of atmospheric inversions, but no independent
land-based flux estimate is available to derive a `between accounting
model' uncertainty. Encouragingly, the top-down atmospheric and the
bottom-up land-based methods converge to consistent mean estimates
within their respective errors, increasing the confidence in the overall
budget. These results also confirm the continued critical role of NH
terrestrial ecosystems in slowing down the atmospheric accumulation of
anthropogenic CO2.
BibTeX:
@article{ciais10a,
  author = {Ciais, Philippe and Canadell, Josep G. and Luyssaert, Sebastiaan and Chevallier, Frederic and Shvidenko, Anatoly and Poussi, Zegbeu and Jonas, Matthias and Peylin, Philippe and King, Anthony Wayne and Schulze, Ernest-Detlef and Piao, Shilong and Roedenbeck, Christian and Peters, Wouter and Breon, Francois-Marie},
  title = {Can we reconcile atmospheric estimates of the Northern terrestrial carbon sink with land-based accounting?},
  journal = {CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY},
  year = {2010},
  volume = {2},
  number = {4},
  pages = {225--230},
  doi = {10.1016/j.cosust.2010.06.008}
}
Ciais P, Dolman AJ, Bombelli A, Duren R, Peregon A, Rayner PJ, Miller C, Gobron N, Kinderman G, Marland G, Gruber N, Chevallier F, Andres RJ, Balsamo G, Bopp L, Breon FM, Broquet G, Dargaville R, Battin TJ, Borges A, Bovensmann H, Buchwitz M, Butler J, Canadell JG, Cook RB, DeFries R, Engelen R, Gurney KR, Heinze C, Heimann M, Held A, Henry M, Law B, Luyssaert S, Miller J, Moriyama T, Moulin C, Myneni RB, Nussli C, Obersteiner M, Ojima D, Pan Y, Paris JD, Piao SL, Poulter B, Plummer S, Quegan S, Raymond P, Reichstein M, Rivier L, Sabine C, Schimel D, Tarasova O, Valentini R, Wang R, van der Werf G, Wickland D, Williams M and Zehner C ({2014}), "Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system", BIOGEOSCIENCES. Vol. {11}({13}), pp. 3547-3602.
Abstract: A globally integrated carbon observation and analysis system is needed
to improve the fundamental understanding of the global carbon cycle, to
improve our ability to project future changes, and to verify the
effectiveness of policies aiming to reduce greenhouse gas emissions and
increase carbon sequestration. Building an integrated carbon observation
system requires transformational advances from the existing sparse,
exploratory framework towards a dense, robust, and sustained system in
all components: anthropogenic emissions, the atmosphere, the ocean, and
the terrestrial biosphere. The paper is addressed to scientists,
policymakers, and funding agencies who need to have a global picture of
the current state of the (diverse) carbon observations. We identify the
current state of carbon observations, and the needs and notional
requirements for a global integrated carbon observation system that can
be built in the next decade. A key conclusion is the substantial
expansion of the ground-based observation networks required to reach the
high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks
for addressing policy-relevant objectives, and attributing flux changes
to underlying processes in each region. In order to establish flux and
stock diagnostics over areas such as the southern oceans, tropical
forests, and the Arctic, in situ observations will have to be
complemented with remote-sensing measurements. Remote sensing offers the
advantage of dense spatial coverage and frequent revisit. A key
challenge is to bring remote-sensing measurements to a level of
long-term consistency and accuracy so that they can be efficiently
combined in models to reduce uncertainties, in synergy with ground-based
data. Bringing tight observational constraints on fossil fuel and land
use change emissions will be the biggest challenge for deployment of a
policy-relevant integrated carbon observation system. This will require
in situ and remotely sensed data at much higher resolution and density
than currently achieved for natural fluxes, although over a small land
area (cities, industrial sites, power plants), as well as the inclusion
of fossil fuel CO2 proxy measurements such as radiocarbon in CO2 and
carbon-fuel combustion tracers. Additionally, a policy-relevant carbon
monitoring system should also provide mechanisms for reconciling
regional top-down (atmosphere-based) and bottom-up (surface-based) flux
estimates across the range of spatial and temporal scales relevant to
mitigation policies. In addition, uncertainties for each observation
data-stream should be assessed. The success of the system will rely on
long-term commitments to monitoring, on improved international
collaboration to fill gaps in the current observations, on sustained
efforts to improve access to the different data streams and make
databases interoperable, and on the calibration of each component of the
system to agreed-upon international scales.
BibTeX:
@article{ciais14a,
  author = {Ciais, P. and Dolman, A. J. and Bombelli, A. and Duren, R. and Peregon, A. and Rayner, P. J. and Miller, C. and Gobron, N. and Kinderman, G. and Marland, G. and Gruber, N. and Chevallier, F. and Andres, R. J. and Balsamo, G. and Bopp, L. and Breon, F. -M. and Broquet, G. and Dargaville, R. and Battin, T. J. and Borges, A. and Bovensmann, H. and Buchwitz, M. and Butler, J. and Canadell, J. G. and Cook, R. B. and DeFries, R. and Engelen, R. and Gurney, K. R. and Heinze, C. and Heimann, M. and Held, A. and Henry, M. and Law, B. and Luyssaert, S. and Miller, J. and Moriyama, T. and Moulin, C. and Myneni, R. B. and Nussli, C. and Obersteiner, M. and Ojima, D. and Pan, Y. and Paris, J. -D. and Piao, S. L. and Poulter, B. and Plummer, S. and Quegan, S. and Raymond, P. and Reichstein, M. and Rivier, L. and Sabine, C. and Schimel, D. and Tarasova, O. and Valentini, R. and Wang, R. and van der Werf, G. and Wickland, D. and Williams, M. and Zehner, C.},
  title = {Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system},
  journal = {BIOGEOSCIENCES},
  year = {2014},
  volume = {11},
  number = {13},
  pages = {3547--3602},
  doi = {10.5194/bg-11-3547-2014}
}
Cochran FV and Brunsell NA ({2012}), "Temporal scales of tropospheric CO2, precipitation, and ecosystem responses in the central Great Plains", REMOTE SENSING OF ENVIRONMENT., DEC, {2012}. Vol. {127}, pp. 316-328.
Abstract: Natural and anthropogenic sources of CO2 around the globe contribute to
mid-tropospheric concentrations, yet it remains unknown how measurements
of mid-tropospheric CO2 relate to regional ecosystem dynamics. NASA
Atmospheric Infrared Sounder (AIRS) measurements of CO2 concentrations
in the mid-troposphere from 2002 to 2010 were examined in relation to
precipitation and vegetation phenology across the US Great Plains.
Wavelet multi-resolution analysis and the information theory metric of
relative entropy were applied to assess regional relationships between
mid-tropospheric CO2, Normalized Difference Vegetation Index (NDVI), and
precipitation (PPT). Results show that AIRS observations of
mid-tropospheric CO2 exchange greater amounts of information with
regional PPT and NDVI at seasonal, annual, and longer time scales
compared to shorter time scales. PPT and NDVI contribute to
mid-tropospheric CO2 at the 18-month time scale, while spatial patterns
seen at this time scale for PIT and mid-tropospheric CO2 are reflective
of the influence of PPT on NDVI at the annual scale. Identification of
these dominant temporal scales may facilitate utilization of AIRS CO2
for monitoring regional source/sink dynamics related to climate and
land-use/cover change. (c) 2012 Elsevier Inc. All rights reserved.
BibTeX:
@article{cochran12a,
  author = {Cochran, Ferdouz V. and Brunsell, Nathaniel A.},
  title = {Temporal scales of tropospheric CO2, precipitation, and ecosystem responses in the central Great Plains},
  journal = {REMOTE SENSING OF ENVIRONMENT},
  year = {2012},
  volume = {127},
  pages = {316--328},
  doi = {10.1016/j.rse.2012.09.012}
}
Collalti A, Marconi S, Ibrom A, Trotta C, Anav A, D'Andrea E, Matteucci G, Montagnani L, Gielen B, Mammarella I, Gruenwald T, Knohl A, Berninger F, Zhao Y, Valentini R and Santini M ({2016}), "Validation of 3D-CMCC Forest Ecosystem Model (v.5.1) against eddy covariance data for 10 European forest sites", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {9}({2}), pp. 479-504.
Abstract: This study evaluates the performances of the new version (v.5.1) of
3D-CMCC Forest Ecosystem Model (FEM) in simulating gross primary
productivity (GPP), against eddy covariance GPP data for 10 FLUXNET
forest sites across Europe. A new carbon allocation module, coupled with
new both phenological and autotrophic respiration schemes, was
implemented in this new daily version. Model ability in reproducing
timing and magnitude of daily and monthly GPP fluctuations is validated
at intra-annual and inter-annual scale, including extreme anomalous
seasons. With the purpose to test the 3D-CMCC FEM applicability over
Europe without a site-related calibration, the model has been
deliberately parametrized with a single set of species-specific
parametrizations for each forest ecosystem. The model consistently
reproduces both in timing and in magnitude daily and monthly GPP
variability across all sites, with the exception of the two
Mediterranean sites. We find that 3D-CMCC FEM tends to better simulate
the timing of inter-annual anomalies than their magnitude within
measurements' uncertainty. In six of eight sites where data are
available, the model well reproduces the 2003 summer drought event.
Finally, for three sites we evaluate whether a more accurate
representation of forest structural characteristics (i.e. cohorts,
forest layers) and species composition can improve model results. In two
of the three sites results reveal that model slightly increases its
performances although, statistically speaking, not in a relevant way.
BibTeX:
@article{collalti16a,
  author = {Collalti, A. and Marconi, S. and Ibrom, A. and Trotta, C. and Anav, A. and D'Andrea, E. and Matteucci, G. and Montagnani, L. and Gielen, B. and Mammarella, I. and Gruenwald, T. and Knohl, A. and Berninger, F. and Zhao, Y. and Valentini, R. and Santini, M.},
  title = {Validation of 3D-CMCC Forest Ecosystem Model (v.5.1) against eddy covariance data for 10 European forest sites},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2016},
  volume = {9},
  number = {2},
  pages = {479--504},
  doi = {10.5194/gmd-9-479-2016}
}
Combe M, de wit AJW, de Arellano JV-G, van der Molen MK, Magliulo V and Peters W ({2017}), "Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., DEC, {2017}. Vol. {122}({12}), pp. {3238-3259}.
Abstract: Carbon exchange over croplands plays an important role in the European
carbon cycle over daily to seasonal time scales. A better description of
this exchange in terrestrial biosphere models-most of which currently
treat crops as unmanaged grasslands-is needed to improve atmospheric CO2
simulations. In the framework we present here, we model gross European
cropland CO2 fluxes with a crop growth model constrained by grain yield
observations. Our approach follows a two-step procedure. In the first
step, we calculate day-to-day crop carbon fluxes and pools with the
WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is
optimized regionally by minimizing the final grain carbon pool
difference to crop yield observations from the Statistical Office of the
European Union. In a second step, we re-run our WOFOST model for the
full European 25 x 25 km gridded domain using the optimized scaling
factors. We combine our optimized crop CO2 fluxes with a simple soil
respiration model to obtain the net cropland CO2 exchange. We assess our
model's ability to represent cropland CO2 exchange using 40 years of
observations at seven European FluxNet sites and compare it with carbon
fluxes produced by a typical terrestrial biosphere model. We conclude
that our new model framework provides a more realistic and strongly
observation-driven estimate of carbon exchange over European croplands.
Its products will be made available to the scientific community through
the ICOS Carbon Portal and serve as a new cropland component in the
CarbonTracker Europe inverse model.
BibTeX:
@article{combe17a,
  author = {Combe, M. and de wit, A. J. W. and de Arellano, J. Vila-Guerau and van der Molen, M. K. and Magliulo, V. and Peters, W.},
  title = {Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2017},
  volume = {122},
  number = {12},
  pages = {3238-3259},
  doi = {{10.1002/2017JG003937}}
}
Cooley D, Breidt FJ, Ogle SM, Schuh AE and Lauvaux T ({2013}), "A constrained least-squares approach to combine bottom-up and top-down CO2 flux estimates", ENVIRONMENTAL AND ECOLOGICAL STATISTICS., MAR, {2013}. Vol. {20}({1}), pp. 129-146.
Abstract: Terrestrial CO2 flux estimates are obtained from two fundamentally
different methods generally termed bottom-up and top-down approaches.
Inventory methods are one type of bottom-up approach which uses various
sources of information such as crop production surveys and forest
monitoring data to estimate the annual CO2 flux at locations covering a
study region. Top-down approaches are various types of atmospheric
inversion methods which use CO2 concentration measurements from
monitoring towers and atmospheric transport models to estimate CO2 flux
over a study region. Both methods can also quantify the uncertainty
associated with their estimates. Historically, these two approaches have
produced estimates that differ considerably. The goal of this work is to
construct a statistical model which sensibly combines estimates from the
two approaches to produce a new estimate of CO2 flux for our study
region. The two approaches have complementary strengths and weaknesses,
and our results show that certain aspects of the uncertainty associated
with each of the approaches are greatly reduced by combining the
methods. Our model is purposefully simple and designed to take the two
approaches' estimates and measures of uncertainty at `face value'.
Specifically, we use a constrained least-squares approach to
appropriately weigh the estimates by the inverse of their variance, and
the constraint imposes agreement between the two sources. Our
application involves nearly 18,000 flux estimates for the upper midwest
United States. The constrained dependencies result in a non-sparse
covariance matrix, but computation requires only minutes due to the
structure of the model.
BibTeX:
@article{cooley13a,
  author = {Cooley, Daniel and Breidt, F. Jay and Ogle, Stephen M. and Schuh, Andrew E. and Lauvaux, Thomas},
  title = {A constrained least-squares approach to combine bottom-up and top-down CO2 flux estimates},
  journal = {ENVIRONMENTAL AND ECOLOGICAL STATISTICS},
  year = {2013},
  volume = {20},
  number = {1},
  pages = {129--146},
  doi = {10.1007/s10651-012-0211-6}
}
Corbin KD (2008), "Investigating causes of regional variations in atmospheric carbon dioxide concentrations". Thesis at: Colorado State University.
BibTeX:
@phdthesis{corbin08a,
  author = {Corbin, Katherine D},
  title = {Investigating causes of regional variations in atmospheric carbon dioxide concentrations},
  school = {Colorado State University},
  year = {2008}
}
Crevoisier C, Sweeney C, Gloor M, Sarmiento JL and Tans PP ({2010}), "Regional US carbon sinks from three-dimensional atmospheric CO2 sampling", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., OCT 26, {2010}. Vol. {107}({43}), pp. 18348-18353.
Abstract: Studies diverge substantially on the actual magnitude of the North
American carbon budget. This is due to the lack of appropriate data and
also stems from the difficulty to properly model all the details of the
flux distribution and transport inside the region of interest. To
sidestep these difficulties, we use here a simple budgeting approach to
estimate land-atmosphere fluxes across North America by balancing the
inflow and outflow of CO2 from the troposphere. We base our study on the
unique sampling strategy of atmospheric CO2 vertical profiles over North
America from the National Oceanic and Atmospheric Administration/Earth
System Research Laboratory aircraft network, from which we infer the
three-dimensional CO2 distribution over the continent. We find a
moderate sink of 0.5 +/- 0.4 PgCy(-1) for the period 2004-2006 for the
coterminous United States, in good agreement with the
forest-inventory-based estimate of the first North American State of the
Carbon Cycle Report, and averaged climate conditions. We find that the
highest uptake occurs in the Midwest and in the Southeast. This
partitioning agrees with independent estimates of crop uptake in the
Midwest, which proves to be a significant part of the US atmospheric
sink, and of secondary forest regrowth in the Southeast. Provided that
vertical profile measurements are continued, our study offers an
independent means to link regional carbon uptake to climate drivers.
BibTeX:
@article{crevoisier10a,
  author = {Crevoisier, Cyril and Sweeney, Colm and Gloor, Manuel and Sarmiento, Jorge L. and Tans, Pieter P.},
  title = {Regional US carbon sinks from three-dimensional atmospheric CO2 sampling},
  journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
  year = {2010},
  volume = {107},
  number = {43},
  pages = {18348--18353},
  doi = {10.1073/pnas.0900062107}
}
Crowell SMR, Kawa SR, Browell EV, Hammerling DM, Moore B, Schaefer K and Doney SC ({2018}), "On the Ability of Space-Based Passive and Active Remote Sensing Observations of CO2 to Detect Flux Perturbations to the Carbon Cycle", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2018}. Vol. {123}({2}), pp. {1460-1477}.
Abstract: Space-borne observations of CO2 are vital to gaining understanding of
the carbon cycle in regions of the world that are difficult to measure
directly, such as the tropical terrestrial biosphere, the high northern
and southern latitudes, and in developing nations such as China.
Measurements from passive instruments such as GOSAT and OCO-2, however,
are constrained by solar zenith angle limitations as well as sensitivity
to the presence of clouds and aerosols. Active measurements such as
those in development for the Active Sensing of CO2 Emissions over
Nights, Days and Seasons (ASCENDS) mission show strong potential for
making measurements in the high-latitude winter and in cloudy regions.
In this work we examine the enhanced flux constraint provided by the
improved coverage from an active measurement such as ASCENDS. The
simulation studies presented here show that with sufficient precision,
ASCENDS will detect permafrost thaw and fossil fuel emissions shifts at
annual and seasonal time scales, even in the presence of transport
errors, representativeness errors, and biogenic flux errors. While OCO-2
can detect some of these perturbations at the annual scale, the seasonal
sampling provided by ASCENDS provides the stronger constraint.
Plain Language Summary Active and passive remote sensors show the
potential to provide unprecedented information on the carbon cycle. With
the all-season sampling, active remote sensors are more capable of
constraining high-latitude emissions. The reduced sensitivity to cloud
and aerosol also makes active sensors more capable of providing
information in cloudy and polluted scenes with sufficient accuracy.
These experiments account for errors that are fundamental to the
top-down approach for constraining emissions, and even including these
sources of error, we show that satellite remote sensors are critical for
understanding the carbon cycle.
BibTeX:
@article{crowell18a,
  author = {Crowell, Sean M. R. and Kawa, S. Randolph and Browell, Edward V. and Hammerling, Dorit M. and Moore, Berrien and Schaefer, Kevin and Doney, Scott C.},
  title = {On the Ability of Space-Based Passive and Active Remote Sensing Observations of CO2 to Detect Flux Perturbations to the Carbon Cycle},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2018},
  volume = {123},
  number = {2},
  pages = {1460-1477},
  doi = {{10.1002/2017JD027836}}
}
Dang X, Lai C-T, Hollinger DY, Schauer AJ, Xiao J, Munger JW, Owensby C and Ehleringer JR ({2011}), "Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., SEP 20, {2011}. Vol. {116}
Abstract: We evaluated an idealized boundary layer (BL) model with simple
parameterizations using vertical transport information from community
model outputs (NCAR/NCEP Reanalysis and ECMWF Interim Analysis) to
estimate regional-scale net CO2 fluxes from 2002 to 2007 at three forest
and one grassland flux sites in the United States. The BL modeling
approach builds on a mixed-layer model to infer monthly average net CO2
fluxes using high-precision mixing ratio measurements taken on flux
towers. We compared BL model net ecosystem exchange (NEE) with estimates
from two independent approaches. First, we compared modeled NEE with
tower eddy covariance measurements. The second approach (EC-MOD) was a
data-driven method that upscaled EC fluxes from towers to regions using
MODIS data streams. Comparisons between modeled CO2 and tower NEE fluxes
showed that modeled regional CO2 fluxes displayed interannual and
intra-annual variations similar to the tower NEE fluxes at the Rannells
Prairie and Wind River Forest sites, but model predictions were
frequently different from NEE observations at the Harvard Forest and
Howland Forest sites. At the Howland Forest site, modeled CO2 fluxes
showed a lag in the onset of growing season uptake by 2 months behind
that of tower measurements. At the Harvard Forest site, modeled CO2
fluxes agreed with the timing of growing season uptake but
underestimated the magnitude of observed NEE seasonal fluctuation. This
modeling inconsistency among sites can be partially attributed to the
likely misrepresentation of atmospheric transport and/or CO2 gradients
between ABL and the free troposphere in the idealized BL model. EC-MOD
fluxes showed that spatial heterogeneity in land use and cover very
likely explained the majority of the data-model inconsistency. We show a
site-dependent atmospheric rectifier effect that appears to have had the
largest impact on ABL CO2 inversion in the North American Great Plains.
We conclude that a systematic BL modeling approach provided new insights
when employed in multiyear, cross-site synthesis studies. These results
can be used to develop diagnostic upscaling tools, improving our
understanding of the seasonal and interannual variability of surface CO2
fluxes.
BibTeX:
@article{dang11a,
  author = {Dang, Xuerui and Lai, Chun-Ta and Hollinger, David Y. and Schauer, Andrew J. and Xiao, Jingfeng and Munger, J. William and Owensby, Clenton and Ehleringer, James R.},
  title = {Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JG001554}
}
Dang Y, Ren W, Tao B, Chen G, Lu C, Yang J, Pan S, Wang G, Li S and Tian H ({2014}), "Climate and Land Use Controls on Soil Organic Carbon in the Loess Plateau Region of China", PLOS ONE., MAY 1, {2014}. Vol. {9}({5})
Abstract: The Loess Plateau of China has the highest soil erosion rate in the
world where billion tons of soil is annually washed into Yellow River.
In recent decades this region has experienced significant climate change
and policy-driven land conversion. However, it has not yet been well
investigated how these changes in climate and land use have affected
soil organic carbon (SOC) storage on the Loess Plateau. By using the
Dynamic Land Ecosystem Model (DLEM), we quantified the effects of
climate and land use on SOC storage on the Loess Plateau in the context
of multiple environmental factors during the period of 1961-2005. Our
results show that SOC storage increased by 0.27 Pg C on the Loess
Plateau as a result of multiple environmental factors during the study
period. About 55% (0.14 Pg C) of the SOC increase was caused by land
conversion from cropland to grassland/forest owing to the government
efforts to reduce soil erosion and improve the ecological conditions in
the region. Historical climate change reduced SOC by 0.05 Pg C
(approximately 19% of the total change) primarily due to a significant
climate warming and a slight reduction in precipitation. Our results
imply that the implementation of ``Grain for Green'' policy may
effectively enhance regional soil carbon storage and hence starve off
further soil erosion on the Loess Plateau.
BibTeX:
@article{dang14a,
  author = {Dang, Yaai and Ren, Wei and Tao, Bo and Chen, Guangsheng and Lu, Chaoqun and Yang, Jia and Pan, Shufen and Wang, Guodong and Li, Shiqing and Tian, Hanqin},
  title = {Climate and Land Use Controls on Soil Organic Carbon in the Loess Plateau Region of China},
  journal = {PLOS ONE},
  year = {2014},
  volume = {9},
  number = {5},
  doi = {10.1371/journal.pone.0095548}
}
Davidson GR, Phillips-Housley A and Stevens MT ({2013}), "Soil-zone adsorption of atmospheric CO2 as a terrestrial carbon sink", GEOCHIMICA ET COSMOCHIMICA ACTA., APR 1, {2013}. Vol. {106}, pp. 44-50.
Abstract: Identifying and quantifying sources and sinks of CO2 is integral to
developing global carbon budgets and effectively modeling climate
change. Adsorption of CO2 onto mineral and soil surfaces has generally
been regarded as an insignificant sink, though few studies have
investigated adsorption on natural materials at temperatures and CO2
concentrations relevant to atmospheric or soil zone conditions. In this
study, annual adsorption at the scale of North America was modeled for
the upper 3 m of the Earth's surface (the root zone) based on our own
and published adsorption data, and results compared with reported
estimates for the North American terrestrial carbon sink during
2000-2005. Our results suggest that adsorption can account for 1-3% of
the average annual sink during these years. At smaller regional scales
where more adsorptive deposits are present, such as volcanic ash or
high-organic soils, the sink may be significantly larger. (C) 2013
Elsevier Ltd. All rights reserved.
BibTeX:
@article{davidson13a,
  author = {Davidson, Gregg R. and Phillips-Housley, Ashley and Stevens, Maria T.},
  title = {Soil-zone adsorption of atmospheric CO2 as a terrestrial carbon sink},
  journal = {GEOCHIMICA ET COSMOCHIMICA ACTA},
  year = {2013},
  volume = {106},
  pages = {44--50},
  doi = {10.1016/j.gca.2012.12.015}
}
Deng F and Chen JM ({2011}), "Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses", BIOGEOSCIENCES. Vol. {8}({11}), pp. 3263-3281.
Abstract: The net surface exchange of CO2 for the years 2002-2007 is inferred from
12 181 atmospheric CO2 concentration data with a time-dependent Bayesian
synthesis inversion scheme. Monthly CO2 fluxes are optimized for 30
regions of the North America and 20 regions for the rest of the globe.
Although there have been many previous multiyear inversion studies, the
reliability of atmospheric inversion techniques has not yet been
systematically evaluated for quantifying regional interannual
variability in the carbon cycle. In this study, the global interannual
variability of the CO2 flux is found to be dominated by terrestrial
ecosystems, particularly by tropical land, and the variations of
regional terrestrial carbon fluxes are closely related to climate
variations. These interannual variations are mostly caused by abnormal
meteorological conditions in a few months in the year or part of a
growing season and cannot be well represented using annual means,
suggesting that we should pay attention to finer temporal climate
variations in ecosystem modeling. We find that, excluding fossil fuel
and biomass burning emissions, terrestrial ecosystems and oceans absorb
an average of 3.63 +/- 0.49 and 1.94 +/- 0.41 PgC yr(-1), respectively.
The terrestrial uptake is mainly in northern land while the tropical and
southern lands contribute 0.62 +/- 0.47, and 0.67 +/- 0.34 PgC yr(-1) to
the sink, respectively. In North America, terrestrial ecosystems absorb
0.89 +/- 0.18 PgC yr(-1) on average with a strong flux density found in
the south-east of the continent.
BibTeX:
@article{deng11a,
  author = {Deng, F. and Chen, J. M.},
  title = {Recent global CO2 flux inferred from atmospheric CO2 observations and its regional analyses},
  journal = {BIOGEOSCIENCES},
  year = {2011},
  volume = {8},
  number = {11},
  pages = {3263--3281},
  doi = {10.5194/bg-8-3263-2011}
}
Deng F, Chen JM, Pan Y, Peters W, Birdsey R, McCullough K and Xiao J ({2013}), "The use of forest stand age information in an atmospheric CO2 inversion applied to North America", BIOGEOSCIENCES. Vol. {10}({8}), pp. 5335-5348.
Abstract: Atmospheric inversions have become an important tool in quantifying
carbon dioxide (CO2) sinks and sources at a variety of spatiotemporal
scales, but associated large uncertainties restrain the inversion
research community from reaching agreement on many important subjects.
We enhanced an atmospheric inversion of the CO2 flux for North America
by introducing spatially explicit information on forest stand age for US
and Canada as an additional constraint, since forest carbon dynamics are
closely related to time since disturbance. To use stand age information
in the inversion, we converted stand age into an age factor, and
included the covariances between subcontinental regions in the inversion
based on the similarity of the age factors. Our inversion results show
that, considering age factors, regions with recently disturbed or old
forests are often nudged towards carbon sources, while regions with
middle-aged productive forests are shifted towards sinks. This conforms
to stand age effects observed in flux networks. At the subcontinental
level, our inverted carbon fluxes agree well with continuous estimates
of net ecosystem carbon exchange (NEE) upscaled from eddy covariance
flux data based on MODIS data. Inverted fluxes with the age constraint
exhibit stronger correlation to these upscaled NEE estimates than those
inverted without the age constraint. While the carbon flux at the
continental and subcontinental scales is predominantly determined by
atmospheric CO2 observations, the age constraint is shown to have
potential to improve the inversion of the carbon flux distribution among
subcontinental regions, especially for regions lacking atmospheric CO2
observations.
BibTeX:
@article{deng13a,
  author = {Deng, F. and Chen, J. M. and Pan, Y. and Peters, W. and Birdsey, R. and McCullough, K. and Xiao, J.},
  title = {The use of forest stand age information in an atmospheric CO2 inversion applied to North America},
  journal = {BIOGEOSCIENCES},
  year = {2013},
  volume = {10},
  number = {8},
  pages = {5335--5348},
  doi = {10.5194/bg-10-5335-2013}
}
Deng F, Jones DBA, Henze DK, Bousserez N, Bowman KW, Fisher JB, Nassar R, O'Dell C, Wunch D, Wennberg PO, Kort EA, Wofsy SC, Blumenstock T, Deutscher NM, Griffith DWT, Hase F, Heikkinen P, Sherlock V, Strong K, Sussmann R and Warneke T ({2014}), "Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({7}), pp. 3703-3727.
Abstract: We have examined the utility of retrieved column-averaged, dry-air mole
fractions of CO2 (XCO2) from the Greenhouse Gases Observing Satellite
(GOSAT) for quantifying monthly, regional flux estimates of CO2, using
the GEOS-Chem four-dimensional variational (4D-Var) data assimilation
system. We focused on assessing the potential impact of biases in the
GOSAT CO2 data on the regional flux estimates. Using different screening
and bias correction approaches, we selected three different subsets of
the GOSAT XCO2 data for the 4D-Var inversion analyses, and found that
the inferred global fluxes were consistent across the three XCO2
inversions. However, the GOSAT observational coverage was a challenge
for the regional flux estimates. In the northern extratropics, the
inversions were more sensitive to North American fluxes than to European
and Asian fluxes due to the lack of observations over Eurasia in winter
and over eastern and southern Asia in summer. The regional flux
estimates were also sensitive to the treatment of the residual bias in
the GOSAT XCO2 data. The largest differences obtained were for temperate
North America and temperate South America, for which the largest spread
between the inversions was 1.02 and 0.96 Pg C, respectively. In the case
of temperate North America, one inversion suggested a strong source,
whereas the second and third XCO2 inversions produced a weak and strong
sink, respectively. Despite the discrepancies in the regional flux
estimates between the three XCO2 inversions, the a posteriori CO2
distributions were in good agreement (with a mean difference between the
three inversions of typically less than 0.5 ppm) with independent data
from the Total Carbon Column Observing Network (TCCON), the surface
flask network, and from the HIAPER Pole-to-Pole Observations (HIPPO)
aircraft campaign. The discrepancy in the regional flux estimates from
the different inversions, despite the agreement of the global flux
estimates suggests the need for additional work to determine the minimum
spatial scales at which we can reliably quantify the fluxes using GOSAT
XCO2. The fact that the a posteriori CO2 from the different inversions
were in good agreement with the independent data although the regional
flux estimates differed significantly, suggests that innovative ways of
exploiting existing data sets, and possibly additional observations, are
needed to better evaluate the inferred regional flux estimates.
BibTeX:
@article{deng14a,
  author = {Deng, F. and Jones, D. B. A. and Henze, D. K. and Bousserez, N. and Bowman, K. W. and Fisher, J. B. and Nassar, R. and O'Dell, C. and Wunch, D. and Wennberg, P. O. and Kort, E. A. and Wofsy, S. C. and Blumenstock, T. and Deutscher, N. M. and Griffith, D. W. T. and Hase, F. and Heikkinen, P. and Sherlock, V. and Strong, K. and Sussmann, R. and Warneke, T.},
  title = {Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {7},
  pages = {3703--3727},
  doi = {10.5194/acp-14-3703-2014}
}
Deng F, Jones DBA, O'Dell CW, Nassar R and Parazoo NC ({2016}), "Combining GOSAT XCO2 observations over land and ocean to improve regional CO2 flux estimates", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 27, {2016}. Vol. {121}({4}), pp. 1896-1913.
Abstract: We used the GEOS-Chem data assimilation system to examine the impact of
combining Greenhouse Gases Observing Satellite (GOSAT) XCO2 data over
land and ocean on regional CO2 flux estimates for 2010-2012. We found
that compared to assimilating only land data, combining land and ocean
data produced an a posteriori CO2 distribution that is in better
agreement with independent data and fluxes that are in closer agreement
with existing top-down and bottom-up estimates. Adding XCO2 data over
oceans changed the tropical land regions from a source of 0.64PgC/yr to
a sink of -0.60PgC/yr and produced a corresponding reduction in the
estimated sink in northern and southern land regions by 0.49PgC/yr and
0.80PgC/yr, respectively. This highlights the importance of improved
observational coverage in the tropics to better quantify the latitudinal
distribution of the terrestrial fluxes. Based only on land XCO2 data, we
estimated a strong source in northern tropical South America, which
experienced wet conditions in 2010-2012. In contrast, with the land and
ocean data, we estimated a sink for this wet region in the north, and a
source for the seasonally dry regions in the south and east, which is
consistent with our understanding of the impact of moisture availability
on the carbon balance of the region. Our results suggest that using
satellite data with a more zonally balanced observational coverage could
help mitigate discrepancies in CO2 flux estimates; further improvement
could be expected with the greater observational coverage provided by
the Orbiting Carbon Observatory-2.
BibTeX:
@article{deng16a,
  author = {Deng, Feng and Jones, Dylan B. A. and O'Dell, Christopher W. and Nassar, Ray and Parazoo, Nicholas C.},
  title = {Combining GOSAT XCO2 observations over land and ocean to improve regional CO2 flux estimates},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2016},
  volume = {121},
  number = {4},
  pages = {1896--1913},
  doi = {10.1002/2015JD024157}
}
Deng A, Lauvaux T, Davis KJ, Gaudet BJ, Miles N, Richardson SJ, Wu K, Sarmiento DP, Hardesty RM and Bonin TA (2017), "Toward reduced transport errors in a high resolution urban CO2 inversion system", Elem Sci Anth.
BibTeX:
@article{deng17a,
  author = {Deng, Aijun and Lauvaux, Thomas and Davis, Kenneth J and Gaudet, Brian J and Miles, Natasha and Richardson, Scott J and Wu, Kai and Sarmiento, Daniel P and Hardesty, R Michael and Bonin, Timothy A},
  title = {Toward reduced transport errors in a high resolution urban CO2 inversion system},
  journal = {Elem Sci Anth},
  year = {2017},
  doi = {10.1525/elementa.133/}
}
Desai AR, Helliker BR, Moorcroft PR, Andrews AE and Berry JA ({2010}), "Climatic controls of interannual variability in regional carbon fluxes from top-down and bottom-up perspectives", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., MAY 1, {2010}. Vol. {115}
Abstract: Observations of regional net ecosystem exchange (NEE) of CO(2) for
1997-2007 were analyzed for climatic controls on interannual variability
(IAV). Quantifying IAV of regional (10(4)-10(6) km(2)) NEE over long
time periods is key to understanding potential feedbacks between climate
and the carbon cycle. Four independent techniques estimated monthly
regional NEE for 10(4) km(2) in a spatially heterogeneous
temperate-boreal transition region of the north central United States,
centered on the Park Falls, Wisconsin, United States, National Oceanic
and Atmospheric Administration tall tower site. These techniques
included two bottom-up methods, based on flux tower upscaling and forest
inventory based demographic modeling, respectively, and two top-down
methods, based on tall tower equilibrium boundary layer budgets and
tracer-transport inversion, respectively. While all four methods
revealed a moderate carbon sink, they diverged significantly in
magnitude. Coherence of relative magnitude and variability of NEE
anomalies was strong across the methods. The strongest coherence was a
trend of declining carbon sink since 2002. Most climatic controls were
not strongly correlated with IAV. Significant controls on IAV were those
related to hydrology, such as water table depth, and atmospheric CO(2).
Weaker relationships were found with phenological controls such as
autumn soil temperature. Hydrologic relationships were strongest with a
1 year lag, potentially highlighting a previously unrecognized predictor
of IAV in this region. These results highlight a need for continued
development of techniques to estimate regional IAV and incorporation of
hydrologic cycling into couple carbon-climate models.
BibTeX:
@article{desai10a,
  author = {Desai, Ankur R. and Helliker, Brent R. and Moorcroft, Paul R. and Andrews, Arlyn E. and Berry, Joseph A.},
  title = {Climatic controls of interannual variability in regional carbon fluxes from top-down and bottom-up perspectives},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2010},
  volume = {115},
  doi = {10.1029/2009JG001122}
}
Desai AR, Moore DJP, Ahue WKM, Wilkes PTV, De Wekker SFJ, Brooks BG, Campos TL, Stephens BB, Monson RK, Burns SP, Quaife T, Aulenbach SM and Schimel DS ({2011}), "Seasonal pattern of regional carbon balance in the central Rocky Mountains from surface and airborne measurements", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., OCT 22, {2011}. Vol. {116}
Abstract: High-elevation forests represent a large fraction of potential carbon
uptake in North America, but this uptake is not well constrained by
observations. Additionally, forests in the Rocky Mountains have recently
been severely damaged by drought, fire, and insect outbreaks, which have
been quantified at local scales but not assessed in terms of carbon
uptake at regional scales. The Airborne Carbon in the Mountains
Experiment was carried out in 2007 partly to assess carbon uptake in
western U. S. mountain ecosystems. The magnitude and seasonal change of
carbon uptake were quantified by (1) paired upwind-downwind airborne CO2
observations applied in a boundary layer budget, (2) a spatially
explicit ecosystem model constrained using remote sensing and flux tower
observations, and (3) a downscaled global tracer transport inversion.
Top-down approaches had mean carbon uptake equivalent to flux tower
observations at a subalpine forest, while the ecosystem model showed
less. The techniques disagreed on temporal evolution. Regional carbon
uptake was greatest in the early summer immediately following snowmelt
and tended to lessen as the region experienced dry summer conditions.
This reduction was more pronounced in the airborne budget and inversion
than in flux tower or upscaling, possibly related to lower snow water
availability in forests sampled by the aircraft, which were lower in
elevation than the tower site. Changes in vegetative greenness
associated with insect outbreaks were detected using satellite
reflectance observations, but impacts on regional carbon cycling were
unclear, highlighting the need to better quantify this emerging
disturbance effect on montane forest carbon cycling.
BibTeX:
@article{desai11a,
  author = {Desai, Ankur R. and Moore, David J. P. and Ahue, William K. M. and Wilkes, Phillip T. V. and De Wekker, Stephan F. J. and Brooks, Bjorn G. and Campos, Teresa L. and Stephens, Britton B. and Monson, Russell K. and Burns, Sean P. and Quaife, Tristan and Aulenbach, Steven M. and Schimel, David S.},
  title = {Seasonal pattern of regional carbon balance in the central Rocky Mountains from surface and airborne measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2011JG001655}
}
Deutscher NM, Sherlock V, Fletcher SEM, Griffith DWT, Notholt J, Macatangay R, Connor BJ, Robinson J, Shiona H, Velazco VA, Wang Y, Wennberg PO and Wunch D ({2014}), "Drivers of column-average CO2 variability at Southern Hemispheric Total Carbon Column Observing Network sites", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({18}), pp. 9883-9901.
Abstract: We investigate factors that drive the variability in total column CO2 at
the Total Carbon Column Observing Network sites in the Southern
Hemisphere using fluxes tagged by process and by source region from the
Carbon-Tracker analysed product as well as the Simple Biosphere model.
We show that the terrestrial biosphere is the largest driver of
variability in the Southern Hemisphere column CO2. However, it does not
dominate in the same fashion as in the Northern Hemisphere. Local-and
hemispheric-scale biomass burning can also play an important role,
particularly at the tropical site, Darwin. The magnitude of seasonal
variability in the column-average dry-air mole fraction of CO2, XCO2, is
also much smaller in the Southern Hemisphere and comparable in magnitude
to the annual increase. Comparison of measurements to the model
simulations highlights that there is some discrepancy between the two
time series, especially in the early part of the Darwin data record. We
show that this mismatch is most likely due to erroneously estimated
local fluxes in the Australian tropical region, which are associated
with enhanced photosynthesis caused by early rainfall during the
tropical monsoon season.
BibTeX:
@article{deutscher14a,
  author = {Deutscher, N. M. and Sherlock, V. and Fletcher, S. E. Mikaloff and Griffith, D. W. T. and Notholt, J. and Macatangay, R. and Connor, B. J. and Robinson, J. and Shiona, H. and Velazco, V. A. and Wang, Y. and Wennberg, P. O. and Wunch, D.},
  title = {Drivers of column-average CO2 variability at Southern Hemispheric Total Carbon Column Observing Network sites},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {18},
  pages = {9883--9901},
  doi = {10.5194/acp-14-9883-2014}
}
Diallo M, Legras B, Ray E, Engel A and Anel JA ({2017}), "Global distribution of CO2 in the upper troposphere and stratosphere", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAR 21, {2017}. Vol. {17}({6}), pp. 3861-3878.
Abstract: In this study, we construct a new monthly zonal mean carbon dioxide
(CO2) distribution from the upper troposphere to the stratosphere over
the 2000-2010 time period. This reconstructed CO2 product is based on a
Lagrangian backward trajectory model driven by ERA-Interim reanalysis
meteorology and tropospheric CO2 measurements. Comparisons of our CO2
product to extratropical in situ measurements from aircraft transects
and balloon profiles show remarkably good agreement. The main features
of the CO2 distribution include (1) relatively large mixing ratios in
the tropical stratosphere; (2) seasonal variability in the extratropics,
with relatively high mixing ratios in the summer and autumn hemisphere
in the 15-20 km altitude layer; and (3) decreasing mixing ratios with
increasing altitude from the upper troposphere to the middle
stratosphere (similar to 35 km). These features are consistent with
expected variability due to the transport of long-lived trace gases by
the stratospheric Brewer-Dobson circulation. The method used here to
construct this CO2 product is unique from other modelling efforts and
should be useful for model and satellite validation in the upper
troposphere and stratosphere as a prior for inversion modelling and to
analyse features of stratosphere-troposphere exchange as well as the
stratospheric circulation and its variability.
BibTeX:
@article{diallo17a,
  author = {Diallo, Mohamadou and Legras, Bernard and Ray, Eric and Engel, Andreas and Anel, Juan A.},
  title = {Global distribution of CO2 in the upper troposphere and stratosphere},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {6},
  pages = {3861--3878},
  doi = {10.5194/acp-17-3861-2017}
}
D\iaz-Isaac LI, Lauvaux T and Davis KJ (2018), "Impact of physical parameterizations and initial conditions on simulated atmospheric transport and CO2 mole fractions in the US Midwest", ATMOSPHERIC CHEMISTRY AND PHYSICS., 14835, 2018. Vol. 18, pp. 14813.
BibTeX:
@article{diaz-isaac18a,
  author = {Liza I. D\iaz-Isaac and Thomas Lauvaux and Kenneth J. Davis},
  title = {Impact of physical parameterizations and initial conditions on simulated atmospheric transport and CO2 mole fractions in the US Midwest},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2018},
  volume = {18},
  pages = {14813},
  url = {https://www.atmos-chem-phys.net/18/14813/2018/acp-18-14813-2018.pdf}
}
Dils B, Buchwitz M, Reuter M, Schneising O, Boesch H, Parker R, Guerlet S, Aben I, Blumenstock T, Burrows JP, Butz A, Deutscher NM, Frankenberg C, Hase F, Hasekamp OP, Heymann J, De Maziere M, Notholt J, Sussmann R, Warneke T, Griffith D, Sherlock V and Wunch D ({2014}), "The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({6}), pp. 1723-1744.
Abstract: Column-averaged dry-air mole fractions of carbon dioxide and methane
have been retrieved from spectra acquired by the TANSO-FTS (Thermal And
Near-infrared Sensor for carbon Observations-Fourier Transform
Spectrometer) and SCIAMACHY (Scanning Imaging Absorption Spectrometer
for Atmospheric Cartography) instruments on board GOSAT (Greenhouse
gases Observing SATellite) and ENVISAT (ENVIronmental SATellite),
respectively, using a range of European retrieval algorithms. These
retrievals have been compared with data from ground-based
high-resolution Fourier transform spectrometers (FTSs) from the Total
Carbon Column Observing Network (TCCON). The participating algorithms
are the weighting function modified differential optical absorption
spectroscopy (DOAS) algorithm (WFMD, University of Bremen), the Bremen
optimal estimation DOAS algorithm (BESD, University of Bremen), the
iterative maximum a posteriori DOAS (IMAP, Jet Propulsion Laboratory
(JPL) and Netherlands Institute for Space Research algorithm (SRON)),
the proxy and full-physics versions of SRON's RemoTeC algorithm (SRPR
and SRFP, respectively) and the proxy and full-physics versions of the
University of Leicester's adaptation of the OCO (Orbiting Carbon
Observatory) algorithm (OCPR and OCFP, respectively). The goal of this
algorithm inter-comparison was to identify strengths and weaknesses of
the various so-called round-robin data sets generated with the various
algorithms so as to determine which of the competing algorithms would
proceed to the next round of the European Space Agency's (ESA)
Greenhouse Gas Climate Change Initiative (GHG-CCI) project, which is the
generation of the so-called Climate Research Data Package (CRDP), which
is the first version of the Essential Climate Variable (ECV)
``greenhouse gases'' (GHGs).
For XCO2, all algorithms reach the precision requirements for inverse
modelling (< 8 ppm), with only WFMD having a lower precision (4.7 ppm)
than the other algorithm products (2.4-2.5 ppm). When looking at the
seasonal relative accuracy (SRA, variability of the bias in space and
time), none of the algorithms have reached the demanding < 0.5 ppm
threshold.
For XCH4, the precision for both SCIAMACHY products (50.2 ppb for IMAP
and 76.4 ppb for WFMD) fails to meet the < 34 ppb threshold for inverse
modelling, but note that this work focusses on the period after the 2005
SCIAMACHY detector degradation. The GOSAT XCH4 precision ranges between
18.1 and 14.0 ppb. Looking at the SRA, all GOSAT algorithm products
reach the < 10 ppm threshold (values ranging between 5.4 and 6.2 ppb).
For SCIAMACHY, IMAP and WFMD have a SRA of 17.2 and 10.5 ppb,
respectively.
BibTeX:
@article{dils14a,
  author = {Dils, B. and Buchwitz, M. and Reuter, M. and Schneising, O. and Boesch, H. and Parker, R. and Guerlet, S. and Aben, I. and Blumenstock, T. and Burrows, J. P. and Butz, A. and Deutscher, N. M. and Frankenberg, C. and Hase, F. and Hasekamp, O. P. and Heymann, J. and De Maziere, M. and Notholt, J. and Sussmann, R. and Warneke, T. and Griffith, D. and Sherlock, V. and Wunch, D.},
  title = {The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2014},
  volume = {7},
  number = {6},
  pages = {1723--1744},
  doi = {10.5194/amt-7-1723-2014}
}
Doherty SJ, Bojinski S, Henderson-Sellers A, Noone K, Goodrich D, Bindoff NL, Church JA, Hibbard KA, Karl TR, Kajefez-Bogataj L, Lynch AH, Parker DE, Prentice IC, Ramaswamy V, Saunders RW, Smith MS, Steffen K, Stocker TF, Thorne PW, Trenberth KE, Verstraete MM and Zwiers FW ({2009}), "LESSONS LEARNED FROM IPCC AR4 Scientific Developments Needed To Understand, Predict, And Respond To Climate Change", BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY., APR, {2009}. Vol. {90}({4}), pp. 497-513.
Abstract: The Fourth Assessment Report (AR4) of the Intergovernmental Panel on
Climate Change (IPCC) concluded that global warming is ``unequivocal''
and that most of the observed increase since the mid-twentieth century
is very likely due to the increase in anthropogenic greenhouse gas
concentrations, with discernible human influences on ocean warming,
continental-average temperatures, temperature extremes, wind patterns,
and other physical and biological indicators, impacting both
socioeconomic and ecological systems. It is now clear that we are
committed to some level of global climate change, and it is imperative
that this be considered when planning future climate research and
observational strategies. The Global Climate Observing System program
(GCOS), the World Climate Research Programme (WCRP), and the
International Geosphere-Biosphere Programme (IGBP) therefore initiated a
process to summarize the lessons learned through AR4 Working Groups I
and II and to identify a set of high-priority modeling and observational
needs. Two classes of recommendations emerged. First is the need to
improve climate models, observational and climate monitoring systems,
and our understanding of key processes. Second, the framework for
climate research and observations must be extended to document impacts
and to guide adaptation and mitigation efforts. Research and
observational strategies specifically aimed at improving our ability to
predict and understand impacts, adaptive capacity, and societal and
ecosystem vulnerabilities will serve both purposes and are the subject
of the specific recommendations made in this paper.
BibTeX:
@article{doherty09a,
  author = {Doherty, Sarah J. and Bojinski, Stephan and Henderson-Sellers, Ann and Noone, Kevin and Goodrich, David and Bindoff, Nathaniel L. and Church, John A. and Hibbard, Kathy A. and Karl, Thomas R. and Kajefez-Bogataj, Lucka and Lynch, Amanda H. and Parker, David E. and Prentice, I. Colin and Ramaswamy, Venkatachalam and Saunders, Roger W. and Smith, Mark Stafford and Steffen, Konrad and Stocker, Thomas F. and Thorne, Peter W. and Trenberth, Kevin E. and Verstraete, Michel M. and Zwiers, Francis W.},
  title = {LESSONS LEARNED FROM IPCC AR4 Scientific Developments Needed To Understand, Predict, And Respond To Climate Change},
  journal = {BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY},
  year = {2009},
  volume = {90},
  number = {4},
  pages = {497--513},
  doi = {10.1175/2008BAMS2643.1}
}
Dolman AJ, Gerbig C, Noilhan J, Sarrat C and Miglietta F ({2009}), "Detecting regional variability in sources and sinks of carbon dioxide: a synthesis", BIOGEOSCIENCES. Vol. {6}({6}), pp. 1015-1026.
Abstract: The current paper reviews the experimental setup of the CarboEurope
Experimental Strategy (CERES) campaigns with the aim of providing an
overview of the instrumentation used, the data-set and associated
modelling. It then assesses progress in the field of regional
observation and modelling of carbon fluxes, bringing the papers of this
special issue into a somewhat broader context of analysis.
Instrumental progress has been obtained in the field of remotely
monitoring from tall towers and the experimental planning. Flux
measurements from aircraft are now capable, within some constraints, to
provide regular regional observations of fluxes of CO(2), latent and
sensible heat.
Considerable effort still needs to be put into calibrating the surface
schemes of models, as they have direct impact on the input of energy,
moisture and carbon fluxes in the boundary layer. Overall, the mesoscale
models appear to be capable of simulating the large scale dynamics of
the region, but in the fine detail, like the precise horizontal and
vertical CO(2) field differences between the models still exist. These
errors translate directly into transport uncertainty, when the forward
simulations are used in inverse mode. Quantification of this
uncertainty, including that of inadequate boundary layer height
modelling, still remains a major challenge for state of the art
mesoscale models. Progress in inverse models has been slow, but has
shown that it is possible to estimate some of the errors involved, and
that using the combination of observations. Overall, the capability to
produce regional, high-resolution estimates of carbon exchange, exist in
potential, but the routine application will require considerable effort,
both in the experimental as in the modelling domain.
BibTeX:
@article{dolman09a,
  author = {Dolman, A. J. and Gerbig, C. and Noilhan, J. and Sarrat, C. and Miglietta, F.},
  title = {Detecting regional variability in sources and sinks of carbon dioxide: a synthesis},
  journal = {BIOGEOSCIENCES},
  year = {2009},
  volume = {6},
  number = {6},
  pages = {1015--1026},
  doi = {10.5194/bg-6-1015-2009}
}
Dolman AJ, van der Werf GR, van der Molen MK, Ganssen G, Erisman JW and Strengers B ({2010}), "A Carbon Cycle Science Update Since IPCC AR-4", AMBIO., JUL, {2010}. Vol. {39}({5-6}), pp. 402-412.
Abstract: We review important advances in our understanding of the global carbon
cycle since the publication of the IPCC AR4. We conclude that: the
anthropogenic emissions of CO2 due to fossil fuel burning have increased
up through 2008 at a rate near to the high end of the IPCC emission
scenarios; there are contradictory analyses whether an increase in
atmospheric fraction, that might indicate a declining sink strength of
ocean and/or land, exists; methane emissions are increasing, possibly
through enhanced natural emission from northern wetland, methane
emissions from dry plants are negligible; old-growth forest take up more
carbon than expected from ecological equilibrium reasoning; tropical
forest also take up more carbon than previously thought, however, for
the global budget to balance, this would imply a smaller uptake in the
northern forest; the exchange fluxes between the atmosphere and ocean
are increasingly better understood and bottom up and observation-based
top down estimates are getting closer to each other; the North Atlantic
and Southern ocean take up less CO2, but it is unclear whether this is
part of the `natural' decadal scale variability; large-scale fires and
droughts, for instance in Amazonia, but also at Northern latitudes, have
lead to significant decreases in carbon uptake on annual timescales; the
extra uptake of CO2 stimulated by increased N-deposition is, from a
greenhouse gas forcing perspective, counterbalanced by the related
additional N2O emissions; the amount of carbon stored in permafrost
areas appears much (two times) larger than previously thought;
preservation of existing marine ecosystems could require a CO2
stabilization as low as 450 ppm; Dynamic Vegetation Models show a wide
divergence for future carbon trajectories, uncertainty in the process
description, lack of understanding of the CO2 fertilization effect and
nitrogen-carbon interaction are major uncertainties.
BibTeX:
@article{dolman10a,
  author = {Dolman, A. J. and van der Werf, G. R. and van der Molen, M. K. and Ganssen, G. and Erisman, J. -W. and Strengers, B.},
  title = {A Carbon Cycle Science Update Since IPCC AR-4},
  journal = {AMBIO},
  year = {2010},
  volume = {39},
  number = {5-6},
  pages = {402--412},
  doi = {10.1007/s13280-010-0083-7}
}
Elias E, Dougherty M, Srivastava P and Laband D ({2013}), "The impact of forest to urban land conversion on streamflow, total nitrogen, total phosphorus, and total organic carbon inputs to the converse reservoir, Southern Alabama, USA", URBAN ECOSYSTEMS., MAR, {2013}. Vol. {16}({1, SI}), pp. 79-107.
Abstract: High total organic carbon (TOC) concentrations in Converse Reservoir, a
water source for Mobile, Alabama, have concerned water treatment
officials due to the potential for disinfection byproduct (DBP)
formation. TOC reacts with chlorine during drinking water treatment to
form DBPs. This study evaluated how increased urbanization can alter
watershed-derived total nitrogen (TN), total phosphorus (TP) and TOC
inputs to the Converse Reservoir. Converse Watershed, on the urban
fringe of Mobile, is projected to undergo urbanization increasing
watershed urban land from 3% in 1992 to 22% urban land by 2020. A
pre-urbanization scenario using 1992 land cover was coupled with 2020
projections of land use. The Loading Simulation Program C++ watershed
model was used to evaluate changes in nutrient concentrations (mg L-1)
and loads (kg) to Converse Reservoir. Urban and suburban growth of 52
km(2) simulated from 1991 to 2005 (15 year) caused overall TN and TP
loads to increase by 109 and 62 respectively. Simulated urban growth
generally increased monthly flows by 15 but resulted in lower
streamflows (2.9 during drought months. Results indicate that
post-urbanization median TN and TP concentrations were 59 and 66br> higher than corresponding pre-urbanization concentrations, whereas TOC
concentrations were 16% lower. An increase in urban flow caused TOC
loads to increase by 26 despite lower post-urbanization TOC
concentrations.
BibTeX:
@article{elias13a,
  author = {Elias, Emile and Dougherty, Mark and Srivastava, Puneet and Laband, David},
  title = {The impact of forest to urban land conversion on streamflow, total nitrogen, total phosphorus, and total organic carbon inputs to the converse reservoir, Southern Alabama, USA},
  journal = {URBAN ECOSYSTEMS},
  year = {2013},
  volume = {16},
  number = {1, SI},
  pages = {79--107},
  doi = {10.1007/s11252-011-0198-z}
}
Fadnavis S, Kumar KR, Tiwari YK and Pozzoli L ({2016}), "Atmospheric CO2 source and sink patterns over the Indian region", ANNALES GEOPHYSICAE. Vol. {34}({2}), pp. 279-291.
Abstract: In this paper we examine CO2 emission hot spots and sink regions over
India as identified from global model simulations during the period
2000-2009. CO2 emission hot spots overlap with locations of densely
clustered thermal power plants, coal mines and other industrial and
urban centres; CO2 sink regions coincide with the locations of dense
forest. Fossil fuel CO2 emissions are compared with two bottom-up
inventories: the Regional Emission inventories in ASia (REAS v1.11;
2000-2009) and the Emission Database for Global Atmospheric Research
(EDGAR v4.2) (2000-2009). Estimated fossil fuel emissions over the hot
spot region are similar to 500-950 gCm(-2) yr(-1) as obtained from the
global model simulation, EDGAR v4.2 and REAS v1.11 emission inventory.
Simulated total fluxes show increasing trends, from 1.39 +/- 1.01br> yr(-1) (19.8 +/- 1.9 TgC yr(-1)) to 6.7 +/- 0.54% yr(-1) (97 +/- 12 TgC
yr(-1)) over the hot spot regions and decreasing trends of -0.95 +/-
1.51% yr(-1) (-1 +/- 2 TgC yr(-1)) to 5.7 +/- 2.89% yr(-1) (-2.3 +/- 2
TgC yr(-1)) over the sink regions. Model-simulated terrestrial ecosystem
fluxes show decreasing trends (increasing CO2 uptake) over the sink
regions. Decreasing trends in terrestrial ecosystem fluxes imply that
forest cover is increasing, which is consistent with India State of
Forest Report (2009). Fossil fuel emissions show statistically
significant increasing trends in all the data sets considered in this
study. Estimated trend in simulated total fluxes over the Indian region
is similar to 4.72 +/- 2.25% yr(-1) (25.6 TgC yr(-1)) which is slightly
higher than global growth rate similar to 3.1-1) during 2000-2010.
BibTeX:
@article{fadnavis16a,
  author = {Fadnavis, Suvarna and Kumar, K. Ravi and Tiwari, Yogesh K. and Pozzoli, Luca},
  title = {Atmospheric CO2 source and sink patterns over the Indian region},
  journal = {ANNALES GEOPHYSICAE},
  year = {2016},
  volume = {34},
  number = {2},
  pages = {279--291},
  doi = {10.5194/angeo-34-279-2016}
}
Fang SX, Zhou LX, Tans PP, Ciais P, Steinbacher M, Xu L and Luan T ({2014}), "In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({5}), pp. 2541-2554.
Abstract: Atmospheric carbon dioxide (CO2) mole fractions were continuously
measured from January 2009 to December 2011 at four atmospheric
observatories in China using cavity ring-down spectroscopy instruments.
The stations are Lin'an (LAN), Longfengshan (LFS), Shangdianzi (SDZ),
and Waliguan (WLG), which are regional (LAN, LFS, SDZ) or global (WLG)
measurement stations of the World Meteorological Organization's Global
Atmosphere Watch program (WMO/ GAW). LAN is located near the megacity of
Shanghai, in China's economically most developed region. LFS is in a
forest and rice production area, close to the city of Harbin in
northeastern China. SDZ is located 150 km northeast of Beijing. WLG,
hosting the longest record of measured CO2 mole fractions in China, is a
high-altitude site in northwestern China recording background CO2
concentration. The CO2 growth rates are 3.7 +/- 1.2 ppm yr(-1) for LAN,
2.7 +/- 0.8 ppm yr(-1) for LFS, 3.5 +/- 1.6 ppm yr(-1) for SDZ, and 2.2
+/- 0.8 ppm yr(-1) (1 sigma ) for WLG during the period of 2009 to 2011.
The highest annual mean CO2 mole fraction of 404.2 +/- 3.9 ppm was
observed at LAN in 2011. A comprehensive analysis of CO2 variations,
their diurnal and seasonal cycles as well as the analysis of the
influence of local sources on the CO2 mole fractions allows a
characterization of the sampling sites and of the key processes driving
the CO2 mole fractions. These data form a basis to improve our
understanding of atmospheric CO2 variations in China and the underlying
fluxes using atmospheric inversion models.
BibTeX:
@article{fang14a,
  author = {Fang, S. X. and Zhou, L. X. and Tans, P. P. and Ciais, P. and Steinbacher, M. and Xu, L. and Luan, T.},
  title = {In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {5},
  pages = {2541--2554},
  doi = {10.5194/acp-14-2541-2014}
}
Fang Y, Michalak AM, Shiga YP and Yadav V ({2014}), "Using atmospheric observations to evaluate the spatiotemporal variability of CO2 fluxes simulated by terrestrial biospheric models", BIOGEOSCIENCES. Vol. {11}({23}), pp. 6985-6997.
Abstract: Terrestrial biospheric models (TBMs) are used to extrapolate local
observations and process-level understanding of land-atmosphere carbon
exchange to larger regions, and serve as predictive tools for examining
carbon-climate interactions. Understanding the performance of TBMs is
thus crucial to the carbon cycle and climate science communities. In
this study, we present and assess an approach to evaluating the
spatiotemporal patterns, rather than aggregated magnitudes, of net
ecosystem exchange (NEE) simulated by TBMs using atmospheric CO2
measurements. The approach is based on statistical model selection
implemented within a high-resolution atmospheric inverse model. Using
synthetic data experiments, we find that current atmospheric
observations are sensitive to the underlying spatiotemporal flux
variability at sub-biome scales for a large portion of North America,
and that atmospheric observations can therefore be used to evaluate
simulated spatiotemporal flux patterns as well as to differentiate
between multiple competing TBMs. Experiments using real atmospheric
observations and four prototypical TBMs further confirm the
applicability of the method, and demonstrate that the performance of
TBMs in simulating the spatiotemporal patterns of NEE varies
substantially across seasons, with best performance during the growing
season and more limited skill during transition seasons. This result is
consistent with previous work showing that the ability of TBMs to model
flux magnitudes is also seasonally-dependent. Overall, the proposed
approach provides a new avenue for evaluating TBM performance based on
sub-biome-scale flux patterns, presenting an opportunity for assessing
and informing model development using atmospheric observations.
BibTeX:
@article{fang14b,
  author = {Fang, Y. and Michalak, A. M. and Shiga, Y. P. and Yadav, V.},
  title = {Using atmospheric observations to evaluate the spatiotemporal variability of CO2 fluxes simulated by terrestrial biospheric models},
  journal = {BIOGEOSCIENCES},
  year = {2014},
  volume = {11},
  number = {23},
  pages = {6985--6997},
  doi = {10.5194/bg-11-6985-2014}
}
Fang Y and Michalak AM ({2015}), "Atmospheric observations inform CO2 flux responses to enviroclimatic drivers", GLOBAL BIOGEOCHEMICAL CYCLES., MAY, {2015}. Vol. {29}({5}), pp. 555-566.
Abstract: Understanding the response of the terrestrial biospheric carbon cycle to
variability in enviroclimatic drivers is critical for predicting
climate-carbon interactions. Here we apply an
atmospheric-inversion-based framework to assess the relationships
between the spatiotemporal patterns of net ecosystem CO2 exchange (NEE)
and those of enviroclimatic drivers. We show that those relationships
can be directly observed at 1 degrees x1 degrees 3-hourly resolution
from atmospheric CO2 measurements for four of seven large biomes in
North America, namely, (i) boreal forests and taiga; (ii) temperate
coniferous forests; (iii) temperate grasslands, savannas, and
shrublands; and (iv) temperate broadleaf and mixed forests. We find that
shortwave radiation plays a dominant role during the growing season over
all four biomes. Specific humidity and precipitation also play key roles
and are associated with decreased CO2 uptake (or increased release). The
explanatory power of specific humidity is especially strong during
transition seasons, while that of precipitation appears during both the
growing and dormant seasons. We further find that the ability of four
prototypical terrestrial biospheric models (TBMs) to represent the
spatiotemporal variability of NEE improves as the influence of radiation
becomes more dominant, implying that TBMs have a better skill in
representing the impact of radiation relative to other drivers. Even so,
we show that TBMs underestimate the strength of the relationship to
radiation and do not fully capture its seasonality. Furthermore, the
TBMs appear to misrepresent the relationship to precipitation and
specific humidity at the examined scales, with relationships that are
not consistent in terms of sign, seasonality, or significance relative
to observations. More broadly, we demonstrate the feasibility of
directly probing relationships between NEE and enviroclimatic drivers at
scales with no direct measurements of NEE, opening the door to the study
of emergent processes across scales and to the evaluation of their
scaling within TBMs.
BibTeX:
@article{fang15a,
  author = {Fang, Yuanyuan and Michalak, Anna M.},
  title = {Atmospheric observations inform CO2 flux responses to enviroclimatic drivers},
  journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
  year = {2015},
  volume = {29},
  number = {5},
  pages = {555--566},
  doi = {10.1002/2014GB005034}
}
Feldman DR, Collins WD, Gero PJ, Torn MS, Mlawer EJ and Shippert TR ({2015}), "Observational determination of surface radiative forcing by CO2 from 2000 to 2010", NATURE., MAR 19, {2015}. Vol. {519}({7543}), pp. {339+}.
Abstract: The climatic impact of CO2 and other greenhouse gases is usually
quantified in terms of radiative forcing', calculated as the difference
between estimates of the Earth's radiation field from pre-industrial and
presentday concentrations of these gases. Radiative transfer models
calculate that the increase in CO2 since 1750 corresponds to a global
annualmean radiative forcing at the tropopause of 1.82 +/- 0.19W m(-2)
(ref. 2). However, despite widespread scientific discussion and
modelling of the climate impacts of well-mixed greenhouse gases, there
is little direct observational evidence of the radiative impact of
increasing atmospheric CO2. Here we present observationally based
evidence of clear-sky CO2 surface radiative forcing that is directly
attributable to the increase, between 2000 and 2010, of 22 parts per
million atmospheric CO2. The time series of this forcing at the two
locations the Southern Great Plains and the North Slope of Alaska are
derived from Atmospheric Emitted Radiance Interferometer spectra'
together with ancillary measurements and thoroughly corroborated
radiative transfer calculations'. The time series both show
statistically significant trends of 0.2 W m(-2) per decade (with
respective uncertainties of +/- 0.06 W m(-2) per decade and 0.07 W m(-2)
per decade) and have seasonal ranges of 0.1-0.2W m(-2). This is
approximately ten per cent of the trend in downwelling longwave
radiation'''. These results confirm theoretical predictions of the
atmospheric greenhouse effect due to anthropogenic emissions, and
provide empirical evidence of how rising CO2 levels, mediated by
temporal variations due to photosynthesis and respiration, are affecting
the surface energy balance.
BibTeX:
@article{feldman15a,
  author = {Feldman, D. R. and Collins, W. D. and Gero, P. J. and Torn, M. S. and Mlawer, E. J. and Shippert, T. R.},
  title = {Observational determination of surface radiative forcing by CO2 from 2000 to 2010},
  journal = {NATURE},
  year = {2015},
  volume = {519},
  number = {7543},
  pages = {339+},
  doi = {10.1038/nature14240}
}
Feldman DR, Collins WD, Biraud SC, Risser MD, Turner DD, Gero PJ, Tadic J, Helmig D, Xie S, Mlawer EJ, Shippert TR and Torn MS ({2018}), "Observationally derived rise in methane surface forcing mediated by water vapour trends", NATURE GEOSCIENCE. Vol. {11}({4}), pp. {238+}.
Abstract: Atmospheric methane (CH4) mixing ratios exhibited a plateau between 1995
and 2006 and have subsequently been increasing. While there are a number
of competing explanations for the temporal evolution of this greenhouse
gas, these prominent features in the temporal trajectory of atmospheric
CH4 are expected to perturb the surface energy balance through radiative
forcing, largely due to the infrared radiative absorption features of
CH4. However, to date this has been determined strictly through
radiative transfer calculations. Here, we present a quantified
observation of the time series of clear-sky radiative forcing by CH4 at
the surface from 2002 to 2012 at a single site derived from
spectroscopic measurements along with line-by-line calculations using
ancillary data. There was no significant trend in CH4 forcing between
2002 and 2006, but since then, the trend in forcing was 0.026 +/- 0.006
(99.7% CI) W m(2) yr(-1). The seasonal-cycle amplitude and secular
trends in observed forcing are influenced by a corresponding seasonal
cycle and trend in atmospheric CH4. However, we find that we must
account for the overlapping absorption effects of atmospheric water
vapour (H2O) and CH4 to explain the observations fully. Thus, the
determination of CH4 radiative forcing requires accurate observations of
both the spatiotemporal distribution of CH4 and the vertically resolved
trends in H2O.
BibTeX:
@article{feldman18a,
  author = {Feldman, D. R. and Collins, W. D. and Biraud, S. C. and Risser, M. D. and Turner, D. D. and Gero, P. J. and Tadic, J. and Helmig, D. and Xie, S. and Mlawer, E. J. and Shippert, T. R. and Torn, M. S.},
  title = {Observationally derived rise in methane surface forcing mediated by water vapour trends},
  journal = {NATURE GEOSCIENCE},
  year = {2018},
  volume = {11},
  number = {4},
  pages = {238+},
  doi = {{10.1038/s41561-018-0085-9}}
}
Feltz ML, Knuteson RO and Revercomb HE ({2017}), "Assessment of COSMIC radio occultation and AIRS hyperspectral IR sounder temperature products in the stratosphere using observed radiances", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 27, {2017}. Vol. {122}({16}), pp. 8593-8616.
Abstract: Upper air temperature is defined as an essential climate variable by the
World Meteorological Organization. Two remote sensing technologies being
promoted for monitoring stratospheric temperatures are GPS radio
occultation (RO) and spectrally resolved IR radiances. This study
assesses RO and hyperspectral IR sounder derived temperature products
within the stratosphere by comparing IR spectra calculated from GPS RO
and IR sounder products to coincident IR observed radiances, which are
used as a reference standard. RO dry temperatures from the University
Corporation for Atmospheric Research (UCAR) Constellation Observing
System for Meteorology, Ionosphere, and Climate (COSMIC) mission are
compared to NASA Atmospheric Infrared Sounder (AIRS) retrievals using a
previously developed profile-to-profile collocation method and vertical
temperature averaging kernels. Brightness temperatures (BTs) are
calculated for both COSMIC and AIRS temperature products and are then
compared to coincident AIRS measurements. The COSMIC calculated minus
AIRS measured BTs exceed the estimated 0.5 K measurement uncertainty for
the winter time extratropics around 35 hPa. These differences are
attributed to seasonal UCAR COSMIC biases. Unphysical vertical
oscillations are seen in the AIRS L2 temperature product in austral
winter Antarctic regions, and results imply a small AIRS tropical warm
bias around similar to 35 hPa in the middle stratosphere.
BibTeX:
@article{feltz17a,
  author = {Feltz, M. L. and Knuteson, R. O. and Revercomb, H. E.},
  title = {Assessment of COSMIC radio occultation and AIRS hyperspectral IR sounder temperature products in the stratosphere using observed radiances},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2017},
  volume = {122},
  number = {16},
  pages = {8593--8616},
  doi = {10.1002/2017JD026704}
}
Flower CE and Gonzalez-Meler MA ({2015}), "Responses of Temperate Forest Productivity to Insect and Pathogen Disturbances", In ANNUAL REVIEW OF PLANT BIOLOGY, VOL 66. Vol. {66}, pp. 547-569. Annual Reviews.
Abstract: Pest and pathogen disturbances are ubiquitous across forest ecosystems,
impacting their species composition, structure, and function. Whereas
severe abiotic disturbances (e.g., clear-cutting and fire) largely reset
successional trajectories, pest and pathogen disturbances cause diffuse
mortality, driving forests into nonanalogous system states. Biotic
perturbations that disrupt forest carbon dynamics either reduce or
enhance net primary production (NPP) and carbon storage, depending on
pathogen type. Relative to defoliators, wood borers and invasive pests
have the largest negative impact on NPP and the longest recovery time.
Forest diversity is an important contributing factor to productivity:
NPP is neutral, marginally enhanced, or reduced in high-diversity stands
in which a small portion of the canopy is affected (temperate deciduous
or mixed forests) but very negative in low-diversity stands in which a
large portion of the canopy is affected (western US forests). Pests and
pathogens reduce forest structural and functional redundancy, affecting
their resilience to future climate change or new outbreaks. Therefore,
pests and pathogens can be considered biotic forcing agents capable of
causing consequences of similar magnitude to climate forcing factors.
BibTeX:
@incollection{flower15a,
  author = {Flower, Charles E. and Gonzalez-Meler, Miquel A.},
  editor = {Merchant, SS},
  title = {Responses of Temperate Forest Productivity to Insect and Pathogen Disturbances},
  booktitle = {ANNUAL REVIEW OF PLANT BIOLOGY, VOL 66},
  publisher = {Annual Reviews},
  year = {2015},
  volume = {66},
  pages = {547--569},
  doi = {10.1146/annurev-arplant-043014-115540}
}
Font A, Morgui JA, Curcoll R, Pouchet I, Casals I and Rodo X ({2010}), "Daily carbon surface fluxes in the West Ebre (Ebro) watershed from aircraft profiling on late June 2007", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 427-440.
Abstract: An intensive aircraft campaign measuring atmospheric CO(2) mixing ratios
was carried out in the central part of the Ebre watershed on late June
2007 to characterize the CO(2) dynamics in the Ebre basin and to
calculate the regional cumulative carbon surface flux. CO(2)
concentrations were obtained from vertical profiles over La Muela (LMU;
41.60 degrees N, 1.1 degrees W) from 900 to 4000 m above the sea level
(masl), horizontal transects at similar to 2000 m 100 km west from LMU,
and continuous measurements at similar to 650 masl. Different estimates
of surface flux from changes in the convective boundary layer (CBL)
CO(2) concentration were obtained following the Integral CBL budgeting
equation (ICBL) and the carbon content integration (CCI) method. Values
of the mean surface flux calculated from the different approaches range
from -2.4 to -7.9 mu molCO(2)/m2s. Regional surface flux calculated from
vertical profiling appears to be consistent in a distance of 70 km away
from the measurement site. The ICBL method is very sensitive to the
accurate determination of the concentration in the entrainment zone. The
overall uncertainty from fluxes calculated from the ICBL method rises to
a value of 70 whereas the uncertainty linked to the CCI method is
55%.
BibTeX:
@article{font10a,
  author = {Font, A. and Morgui, J. -A. and Curcoll, R. and Pouchet, I. and Casals, I. and Rodo, X.},
  title = {Daily carbon surface fluxes in the West Ebre (Ebro) watershed from aircraft profiling on late June 2007},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {427--440},
  doi = {10.1111/j.1600-0889.2010.00469.x}
}
Font A, Morgui JA and Rodo X ({2011}), "Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({4}), pp. 1659-1670.
Abstract: In this study the differences in the measured atmospheric CO2 mixing
ratio at three aircraft profiling sites in NE Spain separated by 60 km
are analyzed in regard to the variability of the surface fluxes in the
regional surface influence area. First, the Regional Potential Surface
Influence (RPSI) for fifty-one days in 2006 is calculated to assess the
vertical, horizontal and temporal extent of the surface influence for
the three sites at the regional scale (10(4) km(2)) at different
altitudes of the profile (600, 1200, 2500 and 4000 meters above the sea
level, ma.s.l.). Second, three flights carried out in 2006 (7 February,
24 August and 29 November) following the Crown Atmospheric Sampling
(CAS) design are presented to study the relation between the measured
CO2 variability and the Potential Surface Influence (PSI) and RPSI
concepts. At 600 and 1200 ma.s.l. the regional signal is confined up to
50 h before the measurements whereas at higher altitudes (2500 and 4000
ma.s.l.) the regional surface influence is only recovered during spring
and summer months. The RPSI from sites separated by similar to 60 km
overlap by up to 70% of the regional surface influence at 600 and 1200
ma.s.l., while the overlap decreases to 10-40% at higher altitudes
(2500 and 4000 ma.s.l.). The scale of the RPSI area is suitable to
understand the differences in the measured CO2 concentration in the
three vertices of the CAS, as CO2 differences are attributed to local
surrounding fluxes (February) or to the variability of regional surface
influence as for the August and November flights. For these two flights,
the variability in the regional scale influences the variability
measured in the local scale. The CAS sampling design for aircraft
measurements appears to be a suitable method to cope with the
variability of a typical grid for inversion models as measurements are
intensified within the PBL and the background concentration is measured
every similar to 10(2) km.
BibTeX:
@article{font11a,
  author = {Font, A. and Morgui, J. -A. and Rodo, X.},
  title = {Assessing the regional surface influence through Backward Lagrangian Dispersion Models for aircraft CO2 vertical profiles observations in NE Spain},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2011},
  volume = {11},
  number = {4},
  pages = {1659--1670},
  doi = {10.5194/acp-11-1659-2011}
}
Foucher PY, Chedin A, Armante R, Boone C, Crevoisier C and Bernath P ({2011}), "Carbon dioxide atmospheric vertical profiles retrieved from space observation using ACE-FTS solar occultation instrument", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({6}), pp. 2455-2470.
Abstract: Major limitations of our present knowledge of the global distribution of
CO2 in the atmosphere are the uncertainty in atmospheric transport and
the sparseness of in situ concentration measurements. Limb viewing
spaceborne sounders such as the Atmospheric Chemistry Experiment Fourier
transform spectrometer (ACE-FTS) offer a vertical resolution of a few
kilometres for profiles, which is much better than currently flying or
planned nadir sounding instruments can achieve. After having
demonstrated the feasibility of obtaining CO2 vertical profiles in the
5-25 km altitude range with an accuracy of about 2 ppm in a previous
study, we present here the results of five years of ACE-FTS observations
in terms of monthly mean profiles of CO2 averaged over 10 degrees
latitude bands for northern mid-latitudes. These results are compared
with in-situ aircraft measurements and with simulations from two
different air transport models. Key features of the measured altitude
distribution of CO2 are shown to be accurately reproduced by the ACE-FTS
retrievals: variation in altitude of the seasonal cycle amplitude and
extrema, seasonal change of the vertical gradient, and mean growth rate.
We show that small but significant differences from model simulations
could result from an over estimation of the model circulation strength
during the northern hemisphere spring. Coupled with column measurements
from a nadir viewing instrument, it is expected that occultation
measurements will bring useful constraints to the surface carbon flux
determination.
BibTeX:
@article{foucher11a,
  author = {Foucher, P. Y. and Chedin, A. and Armante, R. and Boone, C. and Crevoisier, C. and Bernath, P.},
  title = {Carbon dioxide atmospheric vertical profiles retrieved from space observation using ACE-FTS solar occultation instrument},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2011},
  volume = {11},
  number = {6},
  pages = {2455--2470},
  doi = {10.5194/acp-11-2455-2011}
}
Frankenberg C, Bergamaschi P, Butz A, Houweling S, Meirink JF, Notholt J, Petersen AK, Schrijver H, Warneke T and Aben I ({2008}), "Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISAT", GEOPHYSICAL RESEARCH LETTERS., AUG 12, {2008}. Vol. {35}({15})
Abstract: Methane retrievals from near-infrared spectra recorded by the SCIAMACHY
instrument onboard ENVISAT hitherto suggested unexpectedly large
tropical emissions. Even though recent studies confirm substantial
tropical emissions, there were indications for an unresolved error in
the satellite retrievals. Here we identify a retrieval error related to
inaccuracies in water vapor spectroscopic parameters, causing a
substantial overestimation of methane correlated with high water vapor
abundances. We report on the overall implications of an update in water
spectroscopy on methane retrievals with special focus on the tropics
where the impact is largest. The new retrievals are applied in a
four-dimensional variational (4D-VAR) data assimilation system to derive
a first estimate of the impact on tropical CH(4) sources. Compared to
inversions based on previous SCIAMACHY retrievals, annual tropical
emission estimates are reduced from 260 to about 201 Tg CH(4) but still
remain higher than previously anticipated.
BibTeX:
@article{frankenberg08a,
  author = {Frankenberg, Christian and Bergamaschi, Peter and Butz, Andre and Houweling, Sander and Meirink, Jan Fokke and Notholt, Justus and Petersen, Anna Katinka and Schrijver, Hans and Warneke, Thorsten and Aben, Ilse},
  title = {Tropical methane emissions: A revised view from SCIAMACHY onboard ENVISAT},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2008},
  volume = {35},
  number = {15},
  doi = {10.1029/2008GL034300}
}
Frankenberg C, Aben I, Bergamaschi P, Dlugokencky EJ, van Hees R, Houweling S, van der Meer P, Snel R and Tol P ({2011}), "Global column-averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 17, {2011}. Vol. {116}
Abstract: After a decade of stable or slightly decreasing global methane
concentrations, ground-based in situ data show that CH4 began increasing
again in 2007 and that this increase continued through 2009. So far,
space-based retrievals sensitive to the lower troposphere in the time
period under consideration have not been available. Here we report a
long-term data set of column-averaged methane mixing ratios retrieved
from spectra of the Scanning Imaging Absorption Spectrometer for
Atmospheric Cartography (SCIAMACHY) instrument onboard Envisat. The
retrieval quality after 2005 was severely affected by degrading detector
pixels within the methane 2v(3) absorption band. We identified the most
crucial problems in SCIAMACHY detector degradation and overcame the
problem by applying a strict pixel mask as well as a new dark current
characterization. Even though retrieval precision after the end of 2005
is invariably degraded, consistent methane retrievals from 2003 through
2009 are now possible. Regional time series in the Sahara, Australia,
tropical Africa, South America, and Asia show the methane increase in
2007-2009, but we cannot yet draw a firm conclusion concerning the
origin of the increase. Tropical Africa even seems to exhibit a negative
anomaly in 2006, but an impact from changes in SCIAMACHY detector
degradation cannot be excluded yet. Over Assakrem, Algeria, we observed
strong similarities between SCIAMACHY measurements and ground-based data
in deseasonalized time series. We further show long-term SCIAMACHY
xCH(4) averages at high spatial resolution that provide further insight
into methane variations on regional scales. The Red Basin in China
exhibits, on average, the highest methane abundance worldwide, while
other localized features such as the Sudd wetlands in southern Sudan can
also be identified in SCIAMACHY xCH(4) averages.
BibTeX:
@article{frankenberg11a,
  author = {Frankenberg, C. and Aben, I. and Bergamaschi, P. and Dlugokencky, E. J. and van Hees, R. and Houweling, S. and van der Meer, P. and Snel, R. and Tol, P.},
  title = {Global column-averaged methane mixing ratios from 2003 to 2009 as derived from SCIAMACHY: Trends and variability},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JD014849}
}
Frankenberg C, Kulawik SS, Wofsy SC, Chevallier F, Daube B, Kort EA, O'Dell C, Olsen ET and Osterman G ({2016}), "Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({12}), pp. 7867-7878.
Abstract: In recent years, space-borne observations of atmospheric carbon dioxide
(CO2) have been increasingly used in global carbon-cycle studies. In
order to obtain added value from space-borne measurements, they have to
suffice stringent accuracy and precision requirements, with the latter
being less crucial as it can be reduced by just enhanced sample size.
Validation of CO2 column-averaged dry air mole fractions (XCO2) heavily
relies on measurements of the Total Carbon Column Observing Network
(TCCON). Owing to the sparseness of the network and the requirements
imposed on space-based measurements, independent additional validation
is highly valuable. Here, we use observations from the High-Performance
Instrumented Airborne Platform for Environmental Research (HIAPER)
Pole-to-Pole Observations (HIPPO) flights from 01/2009 through 09/2011
to validate CO2 measurements from satellites (Greenhouse Gases Observing
Satellite - GOSAT, Thermal Emission Sounder - TES, Atmospheric Infrared
Sounder - AIRS) and atmospheric inversion models (CarbonTracker CT2013B,
Monitoring Atmospheric Composition and Climate (MACC) v13r1). We find
that the atmospheric models capture the XCO2 variability observed in
HIPPO flights very well, with correlation coefficients (r(2)) of 0.93
and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies
can be observed in profile comparisons at higher latitudes, in
particular at 300aEuro-hPa during the peaks of either carbon uptake or
release. These deviations can be up to 4aEuro-ppm and hint at
misrepresentation of vertical transport.
Comparisons with the GOSAT satellite are of comparable quality, with an
r(2) of 0.85, a mean bias mu of -0.06aEuro-ppm, and a standard deviation
sigma of 0.45aEuro-ppm. TES exhibits an r(2) of 0.75, mu of
0.34aEuro-ppm, and sigma of 1.13aEuro-ppm. For AIRS, we find an r(2) of
0.37, mu of 1.11aEuro-ppm, and sigma of 1.46aEuro-ppm, with
latitude-dependent biases. For these comparisons at least 6, 20, and 50
atmospheric soundings have been averaged for GOSAT, TES, and AIRS,
respectively. Overall, we find that GOSAT soundings over the remote
Pacific Ocean mostly meet the stringent accuracy requirements of about
0.5aEuro-ppm for space-based CO2 observations.
BibTeX:
@article{frankenberg16a,
  author = {Frankenberg, Christian and Kulawik, Susan S. and Wofsy, Steven C. and Chevallier, Frederic and Daube, Bruce and Kort, Eric A. and O'Dell, Christopher and Olsen, Edward T. and Osterman, Gregory},
  title = {Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {12},
  pages = {7867--7878},
  doi = {10.5194/acp-16-7867-2016}
}
Fraser A, Palmer PI, Feng L, Boesch H, Cogan A, Parker R, Dlugokencky EJ, Fraser PJ, Krummel PB, Langenfelds RL, O'Doherty S, Prinn RG, Steele LP, van der Schoot M and Weiss RF ({2013}), "Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({11}), pp. 5697-5713.
Abstract: We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem
chemistry transport model, to estimate regional monthly methane (CH4)
fluxes for the period June 2009-December 2010 using proxy dry-air
column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse
gases Observing SATellite) and/or NOAA ESRL (Earth System Research
Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory)
CH4 surface mole fraction measurements. Global posterior estimates using
GOSAT and/or surface measurements are between 510-516 Tg yr(-1), which
is less than, though within the uncertainty of, the prior global flux of
529 +/- 25 Tg yr(-1). We find larger differences between regional prior
and posterior fluxes, with the largest changes in monthly emissions (75
Tg yr(-1)) occurring in Temperate Eurasia. In non-boreal regions the
error reductions for inversions using the GOSAT data are at least three
times larger (up to 45 than if only surface data are assimilated, a
reflection of the greater spatial coverage of GOSAT, with the two
exceptions of latitudes >60 degrees associated with a data filter and
over Europe where the surface network adequately describes fluxes on our
model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2
model output to investigate model error on quantifying proxy GOSAT XCH4
(involving model XCO2) and inferring methane flux estimates from surface
mole fraction data and show similar resulting fluxes, with differences
reflecting initial differences in the proxy value. Using a series of
observing system simulation experiments (OSSEs) we characterize the
posterior flux error introduced by non-uniform atmospheric sampling by
GOSAT. We show that clear-sky measurements can theoretically reproduce
fluxes within 10% of true values, with the exception of tropical
regions where, due to a large seasonal cycle in the number of
measurements because of clouds and aerosols, fluxes are within 15% of
true fluxes. We evaluate our posterior methane fluxes by incorporating
them into GEOS-Chem and sampling the model at the location and time of
surface CH4 measurements from the AGAGE (Advanced Global Atmospheric
Gases Experiment) network and column XCH4 measurements from TCCON (Total
Carbon Column Observing Network). The posterior fluxes modestly improve
the model agreement with AGAGE and TCCON data relative to prior fluxes,
with the correlation coefficients (r(2)) increasing by a mean of 0.04
(range: -0.17 to 0.23) and the biases decreasing by a mean of 0.4 ppb
(range: -8.9 to 8.4 ppb).
BibTeX:
@article{fraser13a,
  author = {Fraser, A. and Palmer, P. I. and Feng, L. and Boesch, H. and Cogan, A. and Parker, R. and Dlugokencky, E. J. and Fraser, P. J. and Krummel, P. B. and Langenfelds, R. L. and O'Doherty, S. and Prinn, R. G. and Steele, L. P. and van der Schoot, M. and Weiss, R. F.},
  title = {Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {11},
  pages = {5697--5713},
  doi = {10.5194/acp-13-5697-2013}
}
Fu D, Chen B, Zhang H, Wang J, Black TA, Amiro BD, Bohrer G, Bolstad P, Coulter R, Rahman AF, Dunn A, McCaughey JH, Meyers T and Verma S ({2014}), "Estimating landscape net ecosystem exchange at high spatial-temporal resolution based on Landsat data, an improved upscaling model framework, and eddy covariance flux measurements", REMOTE SENSING OF ENVIRONMENT., FEB 5, {2014}. Vol. {141}, pp. 90-104.
Abstract: More accurate estimation of the carbon dioxide flux depends on the
improved scientific understanding of the terrestrial carbon cycle.
Remote-sensing-based approaches to continental-scale estimation of net
ecosystem exchange (NEE) have been developed but coarse spatial
resolution is a source of errors. Here we demonstrate a satellite-based
method of estimating NEE using Landsat TM/ETM + data and an upscaling
framework. The upscaling framework contains flux-footprint climatology
modeling, modified regression tree (MRT) analysis and image fusion. By
scaling NEE measured at flux towers to landscape and regional scales,
this satellite-based method can improve NEE estimation at high
spatial-temporal resolution at the landscape scale relative to methods
based on MODIS data with coarser spatial-temporal resolution. This
method was applied to sixteen flux sites from the Canadian Carbon
Program and AmeriFlux networks located in North America, covering
forest, grass, and cropland biomes. Compared to a similar method using
MODIS data, our estimation is more effective for diagnosing landscape
NEE with the same temporal resolution and higher spatial resolution (30
m versus 1 km) (r(2) = 0.7548 vs. 0.5868, RMSE = 1.3979 vs. 1.7497 g C
m-(2) day(-1), average error = 0.8950 vs. 1.0178 g C m(-2) day(-1),
relative error = 0.47 vs. 0.54 for fused Landsat and MODIS imagery,
respectively). We also compared the regional NEE estimations using
Carbon Tracker, our method and eddy-covariance observations. This study
demonstrates that the data-driven satellite-based NEE diagnosed model
can be used to upscale eddy-flux observations to landscape scales with
high spatial-temporal resolutions. (C) 2013 Elsevier Inc. All rights
reserved.
BibTeX:
@article{fu14a,
  author = {Fu, Dongjie and Chen, Baozhang and Zhang, Huifang and Wang, Juan and Black, T. Andy and Amiro, Brian D. and Bohrer, Gil and Bolstad, Paul and Coulter, Richard and Rahman, Abdullah F. and Dunn, Allison and McCaughey, J. Harry and Meyers, Tilden and Verma, Shashi},
  title = {Estimating landscape net ecosystem exchange at high spatial-temporal resolution based on Landsat data, an improved upscaling model framework, and eddy covariance flux measurements},
  journal = {REMOTE SENSING OF ENVIRONMENT},
  year = {2014},
  volume = {141},
  pages = {90--104},
  doi = {10.1016/j.rse.2013.10.029}
}
Gabrys J (2009), "Sink: the dirt of systems", Environment and Planning D: Society and Space. Vol. 27(4), pp. 666-681.
BibTeX:
@article{gabrys09a,
  author = {Gabrys, Jennifer},
  title = {Sink: the dirt of systems},
  journal = {Environment and Planning D: Society and Space},
  year = {2009},
  volume = {27},
  number = {4},
  pages = {666--681},
  doi = {10.1068/d5708}
}
Gahlot S, Shu S, Jain A and Roy SB (2017), "Estimating Trends and Variation of Net Biome Productivity in India for 1980--2012 Using a Land Surface Model", Geophysical Research Letters.
BibTeX:
@article{gahlot17a,
  author = {S Gahlot and S Shu and AK Jain and S Baidya Roy},
  title = {Estimating Trends and Variation of Net Biome Productivity in India for 1980--2012 Using a Land Surface Model},
  journal = {Geophysical Research Letters},
  year = {2017}
}
Gately CK, Hutyra LR, Wing IS and Brondfield MN ({2013}), "A Bottom up Approach to on-Road CO2 Emissions Estimates: Improved Spatial Accuracy and Applications for Regional Planning", ENVIRONMENTAL SCIENCE & TECHNOLOGY., MAR 5, {2013}. Vol. {47}({5}), pp. 2423-2430.
Abstract: On-road transportation is responsible for 28% of all U.S. fossil-fuel
CO2 emissions. Mapping vehicle emissions at regional scales is
challenging due to data limitations. Existing emission inventories use
spatial proxies such as population and road density to downscale
national or state-level data. Such procedures introduce errors where the
proxy variables and actual emissions are weakly correlated, and limit
analysis of the relationship between emissions and demographic trends at
local scales. We develop an onroad emission inventory product for
Massachusetts-based on roadway-level traffic data obtained from the
Highway Performance Monitoring System (HPMS). We provide annual
estimates of on-road CO2 emissions at a 1 x 1 km grid scale for the
years 1980 through 2008. We compared our results with on-road emissions
estimates from the Emissions Database for Global Atmospheric Research
(EDGAR), with the Vulcan Product, and with estimates derived from state
fuel consumption statistics reported by the Federal Highway
Administration (FHWA). Our model differs from FHWA estimates by less
than 8.5% on average, and is within 596 of Vulcan estimates. We found
that EDGAR estimates systematically exceed FHWA by an average of 22.8br> Panel regression analysis of per-mile CO2 emissions on population
density at the town scale shows a statistically significant correlation
that varies systematically in sign and magnitude as population density
increases. Population density has a positive correlation with per-mile
CO2 emissions for densities below 2000 persons km(-2), above which
increasing density correlates negatively with per-mile emissions.
BibTeX:
@article{gately13a,
  author = {Gately, Conor K. and Hutyra, Lucy R. and Wing, Ian Sue and Brondfield, Max N.},
  title = {A Bottom up Approach to on-Road CO2 Emissions Estimates: Improved Spatial Accuracy and Applications for Regional Planning},
  journal = {ENVIRONMENTAL SCIENCE & TECHNOLOGY},
  year = {2013},
  volume = {47},
  number = {5},
  pages = {2423--2430},
  doi = {10.1021/es304238v}
}
Gately CK (2016), "Emissions from mobile sources: Improved understanding of the drivers of emissions and their spatial patterns". Thesis at: Boston University.
BibTeX:
@phdthesis{gately16a,
  author = {Gately, Conor Kennedy},
  title = {Emissions from mobile sources: Improved understanding of the drivers of emissions and their spatial patterns},
  school = {Boston University},
  year = {2016},
  url = {http://search.proquest.com/openview/660fb3eced8341af00fe6f17a1aee2f4/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Gately CK and Hutyra LR ({2017}), "Large Uncertainties in Urban-Scale Carbon Emissions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 27, {2017}. Vol. {122}({20}), pp. 11242-11260.
Abstract: Accurate estimates of fossil fuel carbon dioxide (FFCO2) emissions are a
critical component of local, regional, and global climate agreements.
Current global inventories of FFCO2 emissions do not directly quantify
emissions at local scales; instead, spatial proxies like population
density, nighttime lights, and power plant databases are used to
downscale emissions from national totals. We have developed a
high-resolution (hourly, 1 km(2)) bottom-up Anthropogenic Carbon
Emissions System (ACES) for FFCO2, based on local activity data for the
year 2011 across the northeastern U.S. We compare ACES with three widely
used global inventories, finding significant differences at regional
(20 and city scales (50-250. At a spatial resolution of 0.1
degrees, inventories differ by over 100% for half of the grid cells in
the domain, with the largest differences in urban areas and oil and gas
production regions. Given recent U.S. federal policy pull backs
regarding greenhouse gas emissions reductions, inventories like ACES are
crucial for U.S. actions, as the impetus for climate leadership has
shifted to city and state governments. The development of a robust
carbon monitoring system to track carbon fluxes is critical for
emissions benchmarking and verification. We show that existing
downscaled inventories are not suitable for urban emissions monitoring,
as they do not consider important local activity patterns. The ACES
methodology is designed for easy updating, making it suitable for
emissions monitoring under most city, regional, and state greenhouse gas
mitigation initiatives, in particular, for the small-and medium-sized
cities that lack the resources to regularly perform their own bottom-up
emissions inventories.
BibTeX:
@article{gately17a,
  author = {Gately, C. K. and Hutyra, L. R.},
  title = {Large Uncertainties in Urban-Scale Carbon Emissions},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2017},
  volume = {122},
  number = {20},
  pages = {11242--11260},
  doi = {10.1002/2017JD027359}
}
Geibel MC (2011), "Measurement of climate-relevant trace gases via infrared spectroscopy". Thesis at: Friedrich-Schiller-Universitat Jena.
BibTeX:
@phdthesis{geibel11a,
  author = {Geibel, Marc Christoph},
  title = {Measurement of climate-relevant trace gases via infrared spectroscopy},
  school = {Friedrich-Schiller-Universitat Jena},
  year = {2011},
  url = {https://d-nb.info/1016620160/34}
}
Gennaretti F, Gea-Izquierdo G, Boucher E, Berninger F, Arseneault D and Guiot J ({2017}), "Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest", BIOGEOSCIENCES., NOV 6, {2017}. Vol. {14}({21}), pp. 4851-4866.
Abstract: A better understanding of the coupling between photosynthesis and carbon
allocation in the boreal forest, together with its associated
environmental factors and mechanistic rules, is crucial to accurately
predict boreal forest carbon stocks and fluxes, which are significant
components of the global carbon budget. Here, we adapted the MAIDEN
ecophysiological forest model to consider important processes for boreal
tree species, such as nonlinear acclimation of photosynthesis to
temperature changes, canopy development as a function of previous-year
climate variables influencing bud formation and the temperature
dependence of carbon partition in summer. We tested these modifications
in the eastern Canadian taiga using black spruce (Picea mariana (Mill.)
B.S.P.) gross primary production and ring width data. MAIDEN explains
90% of the observed daily gross primary production variability, 73% of
the annual ring width variability and 20-30% of its high-frequency
component (i.e., when decadal trends are removed). The positive effect
on stem growth due to climate warming over the last several decades is
well captured by the model. In addition, we illustrate how we improve
the model with each introduced model adaptation and compare the model
results with those of linear response functions. Our results demonstrate
that MAIDEN simulates robust relationships with the most important
climate variables (those detected by classical response-function
analysis) and is a powerful tool for understanding how environmental
factors interact with black spruce ecophysiol-ogy to influence
present-day and future boreal forest carbon fluxes.
BibTeX:
@article{gennaretti17a,
  author = {Gennaretti, Fabio and Gea-Izquierdo, Guillermo and Boucher, Etienne and Berninger, Frank and Arseneault, Dominique and Guiot, Joel},
  title = {Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest},
  journal = {BIOGEOSCIENCES},
  year = {2017},
  volume = {14},
  number = {21},
  pages = {4851--4866},
  doi = {10.5194/bg-14-4851-2017}
}
Georgoulias AK, Kourtidis KA, Buchwitz M, Schneising O and Burrows JP ({2011}), "A case study on the application of SCIAMACHY satellite methane measurements for regional studies: the Greater Area of the Eastern Mediterranean", INTERNATIONAL JOURNAL OF REMOTE SENSING. Vol. {32}({3}), pp. 787-813.
Abstract: Many studies have focused on geological formations, such as mud
volcanoes, which abound in the Greater Area of the Eastern Mediterranean
(GAEM; 25 degrees N-50 degrees N, 5 degrees E-55 degrees E). This
geological source is thought to provide a significant portion of the
global methane (CH4) emissions. However, studies in the GAEM have
focused on specific locations rather than extensive areas, which has led
to a gap in our understanding of the spatial and temporal variability of
CH4 atmospheric mixing ratios. Here, we present characteristics of
methane loading over land in the GAEM using dry air columnar data (XCH4)
retrieved from SCIAMACHY (Scanning Imaging Absorption Spectrometer for
Atmospheric Cartography) satellite measurements with the Weighting
Function Modified Differential Optical Absorption Spectroscopy
(WFM-DOAS) version 1.0 algorithm. We defined methane annual, seasonal
and monthly spatial patterns over the area using 2003 and 2004
measurements. The annual mean XCH4 levels over the study area were
estimated to be 1761 +/- 27 ppb for 2003 and 1758 +/- 26 ppb for 2004. A
seasonal variability with a summer-autumn peak was observed for both
2003 and 2004, August being the month with the highest methane
concentrations. The northeastern part of the area exhibits the highest
XCH4 values while the high elevation regions defined by the triangle of
eastern Turkey, the Persian Gulf and the Caspian Sea and the region of
the eastern coast of the Red Sea exhibit the lowest levels. A
latitudinal gradient was observed for the area during 2003 and 2004. A
comparison of measured XCH4 levels above two of the world's most
renowned mud volcano regions situated in the GAEM with anticipated
methane columnar concentrations as modelled for eruption cases shows
that no mud volcano eruptions were observed from SCIAMACHY during 2003
or 2004.
BibTeX:
@article{georgoulias11a,
  author = {Georgoulias, A. K. and Kourtidis, K. A. and Buchwitz, M. and Schneising, O. and Burrows, J. P.},
  title = {A case study on the application of SCIAMACHY satellite methane measurements for regional studies: the Greater Area of the Eastern Mediterranean},
  journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING},
  year = {2011},
  volume = {32},
  number = {3},
  pages = {787--813},
  doi = {10.1080/01431161.2010.517791}
}
Gerbig C, Dolman AJ and Heimann M ({2009}), "On observational and modelling strategies targeted at regional carbon exchange over continents", BIOGEOSCIENCES. Vol. {6}({10}), pp. 1949-1959.
Abstract: Estimating carbon exchange at regional scales is paramount to
understanding feedbacks between climate and the carbon cycle, but also
to verifying climate change mitigation such as emission reductions and
strategies compensating for emissions such as carbon sequestration. This
paper discusses evidence for a number of important shortcomings of
current generation modelling frameworks designed to provide regional
scale budgets from atmospheric observations. Current top-down and
bottom-up approaches targeted at deriving consistent regional scale
carbon exchange estimates for biospheric and anthropogenic sources and
sinks are hampered by a number of issues: we show that top-down
constraints using point measurements made from tall towers, although
sensitive to larger spatial scales, are however influenced by local
areas much more strongly than previously thought. On the other hand,
classical bottom-up approaches using process information collected at
the local scale, such as from eddy covariance data, need up-scaling and
validation on larger scales. We therefore argue for a combination of
both approaches, implicitly providing the important local scale
information for the top-down constraint, and providing the atmospheric
constraint for up-scaling of flux measurements. Combining these data
streams necessitates quantifying their respective representation errors,
which are discussed. The impact of these findings on future network
design is highlighted, and some recommendations are given.
BibTeX:
@article{gerbig09a,
  author = {Gerbig, C. and Dolman, A. J. and Heimann, M.},
  title = {On observational and modelling strategies targeted at regional carbon exchange over continents},
  journal = {BIOGEOSCIENCES},
  year = {2009},
  volume = {6},
  number = {10},
  pages = {1949--1959},
  doi = {10.5194/bg-6-1949-2009}
}
Geyer NM (2015), "Time-filtered inverse modeling of land-atmosphere carbon exchange". Thesis at: Colorado State University.
BibTeX:
@phdthesis{geyer15a,
  author = {Geyer, Nicholas M},
  title = {Time-filtered inverse modeling of land-atmosphere carbon exchange},
  school = {Colorado State University},
  year = {2015},
  url = {http://search.proquest.com/openview/e038a9c458ca8f6d6358546eff579bf6/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Gilmanov TG, Aires L, Barcza Z, Baron VS, Belelli L, Beringer J, Billesbach D, Bonal D, Bradford J, Ceschia E, Cook D, Corradi C, Frank A, Gianelle D, Gimeno C, Gruenwald T, Guo H, Hanan N, Haszpra L, Heilman J, Jacobs A, Jones MB, Johnson DA, Kiely G, Li S, Magliulo V, Moors E, Nagy Z, Nasyrov M, Owensby C, Pinter K, Pio C, Reichstein M, Sanz MJ, Scott R, Soussana JF, Stoy PC, Svejcar T, Tuba Z and Zhou G ({2010}), "Productivity, Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements", RANGELAND ECOLOGY & MANAGEMENT., JAN, {2010}. Vol. {63}({1}), pp. 16-39.
Abstract: Grasslands and agroecosystems occupy one-third of the terrestrial area,
but their contribution to the global carbon cycle remains uncertain. We
used a set of 316 site-years of CO(2) exchange measurements to quantify
gross primary productivity, respiration, and light-response parameters
of grasslands, shrublands/savanna, wetlands, and cropland ecosystems
worldwide. We analyzed data from 72 global flux-tower sites partitioned
into gross photosynthesis and ecosystem respiration with the use of the
light-response method (Gilmanov, T. G., D. A. Johnson, and N. Z.
Saliendra. 2003. Growing season CO(2) fluxes in a sagebrushsteppe
ecosystem in Idaho: Bowen ratio/energy balance measurements and
modeling. Basic and Applied Ecology 4:167-183) from the RANGEFLUX and
WORLDGRASSAGRIFLUX data sets supplemented by 46 sites from the FLUXNET
La Thuile data set partitioned with the use of the temperature-response
method (Reichstein, M., E. Falge, D. Baldocchi, D. Papale, R. Valentini,
M. Aubinet, P. Berbigier, C. Bernhofer, N. Buchmann, M. Falk, T.
Gilmanov, A. Granier, T. Grunwald, K. Havrankova, D. Janous, A. Knohl,
T. Laurela, A. Lohila, D. Loustau, G. Matteucci, T. Meyers, F.
Miglietta, J.M. Ourcival, D. Perrin, J. Pumpanen, S. Rambal, E.
Rotenberg, M. Sanz, J. Tenhunen, G. Seufert, F. Vaccari, T. Vesala, and
D. Yakir. 2005. On the separation of net ecosystem exchange into
assimilation and ecosystem respiration: review and improved algorithm.
Global Change Biology 11: 1.424-1439). Maximum values of the quantum
yield (alpha = 75 mmol.mol(-1)), photosynthetic capacity (A(max) = 3.4
mg CO(2) . m(-2).s-1), gross photosynthesis (P(g,max) = 1.16 g CO(2) .
m(-2).d(-1)), and ecological light-use efficiency (epsilon(ecol) = 59
mmol . mol(-1)) of managed grasslands and high-production croplands
exceeded those of most forest ecosystems, indicating the potential of
nonforest ecosystems for uptake of atmospheric CO(2). Maximum values of
gross primary production (8 600 g CO(2) . m(-2).yr(-1)), total ecosystem
respiration (7 900 g CO(2) . m(-2).yr(-1)), and net CO(2) exchange (2
400 g CO(2) . m(-2).yr(-1)) were observed for intensively managed
grasslands and high-yield crops, and are comparable to or higher than
those for forest ecosystems, excluding some tropical forests. On
average, 80% of the nonforest sites were apparent sinks for atmospheric
CO(2), with mean net uptake of 700 g CO(2) . m(-2).yr(-1) for intensive
grasslands and 933 g CO(2) . m(-2).d(-1) for croplands. However, part of
these apparent sinks is accumulated in crops and forage, which are
carbon pools that are harvested, transported, and decomposed off site.
Therefore, although agricultural fields may be predominantly sinks for
atmospheric CO(2), this does not imply that they are necessarily
increasing their carbon stock.
BibTeX:
@article{gilmanov10a,
  author = {Gilmanov, Tagir G. and Aires, L. and Barcza, Z. and Baron, V. S. and Belelli, L. and Beringer, J. and Billesbach, D. and Bonal, D. and Bradford, J. and Ceschia, E. and Cook, D. and Corradi, C. and Frank, A. and Gianelle, D. and Gimeno, C. and Gruenwald, T. and Guo, Haiqiang and Hanan, N. and Haszpra, L. and Heilman, J. and Jacobs, A. and Jones, M. B. and Johnson, D. A. and Kiely, G. and Li, Shenggong and Magliulo, V. and Moors, E. and Nagy, Z. and Nasyrov, M. and Owensby, C. and Pinter, K. and Pio, C. and Reichstein, M. and Sanz, M. J. and Scott, R. and Soussana, J. F. and Stoy, P. C. and Svejcar, T. and Tuba, Z. and Zhou, Guangsheng},
  title = {Productivity, Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements},
  journal = {RANGELAND ECOLOGY & MANAGEMENT},
  year = {2010},
  volume = {63},
  number = {1},
  pages = {16--39},
  doi = {10.2111/REM-D-09-00072.1}
}
Glaser R, Castello-Blindt PO and Yin J (2013), "Biomimetic Approaches to Reversible CO2 Capture from Air. N-Methylcarbaminic Acid Formation in Rubsico-Inspired Models", New and Future Developments in Catalysis: Activation of Carbon Dioxide. , pp. 501-534.
BibTeX:
@article{glaser13a,
  author = {Glaser, Rainer and Castello-Blindt, Paula O and Yin, Jian},
  title = {Biomimetic Approaches to Reversible CO2 Capture from Air. N-Methylcarbaminic Acid Formation in Rubsico-Inspired Models},
  journal = {New and Future Developments in Catalysis: Activation of Carbon Dioxide},
  year = {2013},
  pages = {501--534},
  url = {https://faculty.missouri.edu/ glaserr/vitpub/NMCA_Chapter.pdf}
}
Gockede M, Michalak AM, Vickers D, Turner DP and Law BE ({2010}), "Atmospheric inverse modeling to constrain regional-scale CO2 budgets at high spatial and temporal resolution", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 14, {2010}. Vol. {115}
Abstract: We present an inverse modeling framework designed to constrain CO2
budgets at regional scales. The approach captures atmospheric transport
processes in high spatiotemporal resolution by coupling a mesoscale
model with Lagrangian Stochastic backward trajectories. Terrestrial
biosphere CO2 emissions are generated through a simple diagnostic flux
model that splits the net ecosystem exchange into its major components
of gross primary productivity and autotrophic and heterotrophic
respirations. The modeling framework assimilates state-of-the-art data
sets for advected background CO2 and anthropogenic fossil fuel emissions
as well as highly resolved remote sensing products. We introduce a
Bayesian inversion setup, optimizing a posteriori flux base rates for
surface types that are defined through remote sensing information. This
strategy significantly reduces the number of parameters to be optimized
compared with solving fluxes for each individual grid cell, thus
permitting description of the surface in a very high resolution. The
model is tested using CO2 concentrations measured in the fall and winter
of 2006 at two AmeriFlux sites in Oregon. Because this database does not
cover a full seasonal cycle, we focus on conducting model sensitivity
tests rather than producing quantitative CO2 flux estimates. Sensitivity
tests on the influence of spatial and temporal resolution indicate that
optimum results can be obtained using 4 h time steps and grid sizes of 6
km or less. Further tests demonstrate the importance of dividing biome
types by ecoregions to capture their different biogeochemical responses
to external forcings across climatic gradients. Detailed stand age
information was shown to have a positive effect on model performance.
BibTeX:
@article{gockede10a,
  author = {Gockede, Mathias and Michalak, Anna M. and Vickers, Dean and Turner, David P. and Law, Beverly E.},
  title = {Atmospheric inverse modeling to constrain regional-scale CO2 budgets at high spatial and temporal resolution},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2010},
  volume = {115},
  doi = {10.1029/2009JD012257}
}
Gockede M, Turner DP, Michalak AM, Vickers D and Law BE ({2010}), "Sensitivity of a subregional scale atmospheric inverse CO2 modeling framework to boundary conditions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 23, {2010}. Vol. {115}
Abstract: We present an atmospheric inverse modeling framework to constrain
terrestrial biosphere CO2 exchange processes at subregional scales. The
model is operated at very high spatial and temporal resolution, using
the state of Oregon in the northwestern United States as the model
domain. The modeling framework includes mesoscale atmospheric
simulations coupled to Lagrangian transport, a biosphere flux model that
considers, e.g., the effects of drought stress and disturbance on
photosynthesis and respiration CO2 fluxes, and a Bayesian optimization
approach. This study focuses on the impact of uncertainties in advected
background mixing ratios and fossil fuel emissions on simulated flux
fields, both taken from external data sets. We found the simulations to
be highly sensitive to systematic changes in advected background CO2,
while shifts in fossil fuel emissions played a minor role. Correcting
for offsets in the background mixing ratios shifted annual CO2 budgets
by about 47% and improved the correspondence with the output produced
by bottom-up modeling frameworks. Inversion results were robust against
shifts in fossil fuel emissions, which is likely a consequence of
relatively low emission rates in Oregon.
BibTeX:
@article{gockede10b,
  author = {Gockede, Mathias and Turner, David P. and Michalak, Anna M. and Vickers, Dean and Law, Beverly E.},
  title = {Sensitivity of a subregional scale atmospheric inverse CO2 modeling framework to boundary conditions},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2010},
  volume = {115},
  doi = {10.1029/2010JD014443}
}
Gomes D, Vicente LE, Silva R, Paula S, Maçorano RP, Victoria D and Batistella M (2013), "Uso de dados MODIS e AIRS para obten¸ cão de parâmetros de corre¸ cão atmosférica", Simpósio Brasileiro de Sensoriamento Remoto. Vol. 16, pp. 8019-8026.
BibTeX:
@article{gomes13a,
  author = {Gomes, Daniel and Vicente, Luiz Eduardo and Silva, RFB and Paula, SC and Maçorano, Renan Pfister and Victoria, DC and Batistella, Mateus},
  title = {Uso de dados MODIS e AIRS para obten¸ cão de parâmetros de corre¸ cão atmosférica},
  journal = {Simpósio Brasileiro de Sensoriamento Remoto},
  year = {2013},
  volume = {16},
  pages = {8019--8026},
  url = {https://ainfo.cnptia.embrapa.br/digital/bitstream/item/82762/1/DanielSBSR.pdf}
}
Gourdji SM, Hirsch AI, Mueller KL, Yadav V, Andrews AE and Michalak AM ({2010}), "Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({13}), pp. 6151-6167.
Abstract: A series of synthetic data experiments is performed to investigate the
ability of a regional atmospheric inversion to estimate grid-scale CO2
fluxes during the growing season over North America. The inversions are
performed within a geostatistical framework without the use of any prior
flux estimates or auxiliary variables, in order to focus on the
atmospheric constraint provided by the nine towers collecting
continuous, calibrated CO2 measurements in 2004. Using synthetic
measurements and their associated concentration footprints, flux and
model-data mismatch covariance parameters are first optimized, and then
fluxes and their uncertainties are estimated at three different temporal
resolutions. These temporal resolutions, which include a four-day
average, a four-day-average diurnal cycle with 3-hourly increments, and
3-hourly fluxes, are chosen to help assess the impact of temporal
aggregation errors on the estimated fluxes and covariance parameters.
Estimating fluxes at a temporal resolution that can adjust the diurnal
variability is found to be critical both for recovering covariance
parameters directly from the atmospheric data, and for inferring
accurate ecoregion-scale fluxes. Accounting for both spatial and
temporal a priori covariance in the flux distribution is also found to
be necessary for recovering accurate a posteriori uncertainty bounds on
the estimated fluxes. Overall, the results suggest that even a fairly
sparse network of 9 towers collecting continuous CO2 measurements across
the continent, used with no auxiliary information or prior estimates of
the flux distribution in time or space, can be used to infer relatively
accurate monthly ecoregion scale CO2 surface fluxes over North America
within estimated uncertainty bounds. Simulated random transport error is
shown to decrease the quality of flux estimates in under-constrained
areas at the ecoregion scale, although the uncertainty bounds remain
realistic. While these synthetic data inversions do not consider all
potential issues associated with using actual measurement data, e.g.
systematic transport errors or problems with the boundary conditions,
they help to highlight the impact of inversion setup choices, and help
to provide a baseline set of CO2 fluxes for comparison with estimates
from future real-data inversions.
BibTeX:
@article{gourdji10a,
  author = {Gourdji, S. M. and Hirsch, A. I. and Mueller, K. L. and Yadav, V. and Andrews, A. E. and Michalak, A. M.},
  title = {Regional-scale geostatistical inverse modeling of North American CO2 fluxes: a synthetic data study},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {13},
  pages = {6151--6167},
  doi = {10.5194/acp-10-6151-2010}
}
Gourdji SM (2011), "Improved estimates of regional-scale land-atmosphere Carbon dioxide exchange using geostatistical atmospheric inverse models". Thesis at: University of Michigan.
BibTeX:
@phdthesis{gourdji11a,
  author = {Gourdji, Sharon Muzli},
  title = {Improved estimates of regional-scale land-atmosphere Carbon dioxide exchange using geostatistical atmospheric inverse models},
  school = {University of Michigan},
  year = {2011},
  url = {http://search.proquest.com/openview/331603ec402236ba8e528454f7373a97/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Gourdji SM, Mueller KL, Yadav V, Huntzinger DN, Andrews AE, Trudeau M, Petron G, Nehrkorn T, Eluszkiewicz J, Henderson J, Wen D, Lin J, Fischer M, Sweeney C and Michalak AM ({2012}), "North American CO2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion", BIOGEOSCIENCES. Vol. {9}({1}), pp. 457-475.
Abstract: Atmospheric inversion models have the potential to quantify CO2 fluxes
at regional, sub-continental scales by taking advantage of near-surface
CO2 mixing ratio observations collected in areas with high flux
variability. This study presents results from a series of regional
geostatistical inverse models (GIM) over North America for 2004, and
uses them as the basis for an inter-comparison to other inversion
studies and estimates from biospheric models collected through the North
American Carbon Program Regional and Continental Interim Synthesis.
Because the GIM approach does not require explicit prior flux estimates
and resolves fluxes at fine spatiotemporal scales (i.e. 1 degrees x 1
degrees, 3-hourly in this study), it avoids temporal and spatial
aggregation errors and allows for the recovery of realistic spatial
patterns from the atmospheric data relative to previous inversion
studies. Results from a GIM inversion using only available atmospheric
observations and a fine-scale fossil fuel inventory were used to confirm
the quality of the inventory and inversion setup. An inversion
additionally including auxiliary variables from the North American
Regional Reanalysis found inferred relationships with flux consistent
with physiological understanding of the biospheric carbon cycle.
Comparison of GIM results with bottom-up biospheric models showed
stronger agreement during the growing relative to the dormant season, in
part because most of the biospheric models do not fully represent
agricultural land-management practices and the fate of both residual
biomass and harvested products. Comparison to earlier inversion studies
pointed to aggregation errors as a likely source of bias in previous
subcontinental scale flux estimates, particularly for inversions that
adjust fluxes at the coarsest scales and use atmospheric observations
averaged over long periods. Finally, whereas the continental CO2
boundary conditions used in the GIM inversions have a minor impact on
spatial patterns, they have a substantial impact on the continental
carbon budget, with a difference of 0.8 PgC yr(-1) in the total
continental flux resulting from the use of two plausible sets of
boundary CO2 mixing ratios. Overall, this inter-comparison study helps
to assess the state of the science in estimating regional-scale CO2
fluxes, while pointing towards the path forward for improvements in
future top-down and bottom-up modeling efforts.
BibTeX:
@article{gourdji12a,
  author = {Gourdji, S. M. and Mueller, K. L. and Yadav, V. and Huntzinger, D. N. and Andrews, A. E. and Trudeau, M. and Petron, G. and Nehrkorn, T. and Eluszkiewicz, J. and Henderson, J. and Wen, D. and Lin, J. and Fischer, M. and Sweeney, C. and Michalak, A. M.},
  title = {North American CO2 exchange: inter-comparison of modeled estimates with results from a fine-scale atmospheric inversion},
  journal = {BIOGEOSCIENCES},
  year = {2012},
  volume = {9},
  number = {1},
  pages = {457--475},
  doi = {10.5194/bg-9-457-2012}
}
Graven HD and Gruber N ({2011}), "Continental-scale enrichment of atmospheric (CO2)-C-14 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({23}), pp. 12339-12349.
Abstract: The C-14-free fossil carbon added to atmospheric CO2 by combustion
dilutes the atmospheric C-14/C ratio (Delta C-14), potentially providing
a means to verify fossil CO2 emissions calculated using economic
inventories. However, sources of C-14 from nuclear power generation and
spent fuel reprocessing can counteract this dilution and may bias
C-14/C-based estimates of fossil fuel-derived CO2 if these nuclear
influences are not correctly accounted for. Previous studies have
examined nuclear influences on local scales, but the potential for
continental-scale influences on Delta C-14 has not yet been explored. We
estimate annual C-14 emissions from each nuclear site in the world and
conduct an Eulerian transport modeling study to investigate the
continental-scale, steady-state gradients of Delta C-14 caused by
nuclear activities and fossil fuel combustion. Over large regions of
Europe, North America and East Asia, nuclear enrichment may offset at
least 20% of the fossil fuel dilution in Delta C-14, corresponding to
potential biases of more than -0.25 ppm in the CO2 attributed to fossil
fuel emissions, larger than the bias from plant and soil respiration in
some areas. Model grid cells including high C-14-release reactors or
fuel reprocessing sites showed much larger nuclear enrichment, despite
the coarse model resolution of 1.8 degrees x 1.8 degrees. The recent
growth of nuclear C-14 emissions increased the potential nuclear bias
over 1985-2005, suggesting that changing nuclear activities may
complicate the use of Delta C-14 observations to identify trends in
fossil fuel emissions. The magnitude of the potential nu-clear bias is
largely independent of the choice of reference station in the context of
continental-scale Eulerian transport and inversion studies, but could
potentially be reduced by an appropriate choice of reference station in
the context of local-scale assessments.
BibTeX:
@article{graven11a,
  author = {Graven, H. D. and Gruber, N.},
  title = {Continental-scale enrichment of atmospheric (CO2)-C-14 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2011},
  volume = {11},
  number = {23},
  pages = {12339--12349},
  doi = {10.5194/acp-11-12339-2011}
}
Guan K (2013), "Hydrological variability on vegetation seasonality, productivity and composition in tropical ecosystems of Africa". Thesis at: Princeton University.
BibTeX:
@phdthesis{guan13a,
  author = {Guan, Kaiyu},
  title = {Hydrological variability on vegetation seasonality, productivity and composition in tropical ecosystems of Africa},
  school = {Princeton University},
  year = {2013},
  url = {http://search.proquest.com/openview/bdb3c89d79b0a9555cf6e3419d6a81d0/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Guan K, Medvigy D, Wood EF, Caylor KK, Li S and Jeong S-J ({2014}), "Deriving Vegetation Phenological Time and Trajectory Information Over Africa Using SEVIRI Daily LAI", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., FEB, {2014}. Vol. {52}({2}), pp. 1113-1130.
Abstract: Vegetation phenology is closely connected to the terrestrial carbon
budget, and interacts with the atmosphere through surface water and
energy exchange. A comprehensive and detailed characterization of the
spatio-temporal pattern of vegetation phenology can be used to improve
the understanding of interactions between vegetation and climate in
Africa. This research provides an approach to derive phenology time and
trajectory parameters by optimally fitting a double-logistic curve to
daily remotely sensed leaf area index (LAI) from the spinning enhanced
visible and infrared imager. The proposed algorithm can reconstruct the
temporal LAI trajectory based on the optimized parameters with a high
accuracy, and provides user-defined phenological timing information
(e.g., start/end of the growing season) and trajectory information
(e.g., leaf emergence/senescence rate and length) using these fitted
parameters. Both single and double growing-season cases have been
considered with a spatial classification scheme implemented over Africa.
The newly derived vegetation phenology of Africa exhibits emerging
spatial patterns in growing season length, asymmetric green-up and
green-off length/rate, and distinctive phenological features of cropland
and natural vegetation. This approach has the potential to be applied
globally, and the derived vegetation phenological information will
improve dynamic vegetation modeling and climate prediction.
BibTeX:
@article{guan14a,
  author = {Guan, Kaiyu and Medvigy, David and Wood, Eric F. and Caylor, Kelly K. and Li, Shi and Jeong, Su-Jong},
  title = {Deriving Vegetation Phenological Time and Trajectory Information Over Africa Using SEVIRI Daily LAI},
  journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
  year = {2014},
  volume = {52},
  number = {2},
  pages = {1113--1130},
  doi = {10.1109/TGRS.2013.2247611}
}
Guerlet S, Butz A, Schepers D, Basu S, Hasekamp OP, Kuze A, Yokota T, Blavier JF, Deutscher NM, Griffith DWT, Hase F, Kyro E, Morino I, Sherlock V, Sussmann R, Galli A and Aben I ({2013}), "Impact of aerosol and thin cirrus on retrieving and validating XCO2 from GOSAT shortwave infrared measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 27, {2013}. Vol. {118}({10}), pp. 4887-4905.
Abstract: Inadequate treatment of aerosol scattering can be a significant source
of error when retrieving column-averaged dry-air mole fractions of CO2
(XCO2) from space-based measurements of backscattered solar shortwave
radiation. We have developed a retrieval algorithm, RemoTeC, that
retrieves three aerosol parameters (amount, size, and height)
simultaneously with XCO2. Here we evaluate the ability of RemoTeC to
account for light path modifications by clouds, subvisual cirrus, and
aerosols when retrieving XCO2 from Greenhouse Gases Observing Satellite
(GOSAT) Thermal and Near-infrared Sensor for carbon Observation
(TANSO)-Fourier Transform Spectrometer (FTS) measurements. We first
evaluate a cloud filter based on measurements from the Cloud and Aerosol
Imager and a cirrus filter that uses radiances measured by TANSO-FTS in
the 2micron spectral region, with strong water absorption. For the
cloud-screened scenes, we then evaluate errors due to aerosols. We find
that RemoTeC is well capable of accounting for scattering by aerosols
for values of aerosol optical thickness at 750nm up to 0.25. While no
significant correlation of errors is found with albedo, correlations are
found with retrieved aerosol parameters. To further improve the XCO2
accuracy, we propose and evaluate a bias correction scheme. Measurements
from 12 ground-based stations of the Total Carbon Column Observing
Network (TCCON) are used as a reference in this study. We show that
spatial colocation criteria may be relaxed using additional constraints
based on modeled XCO2 gradients, to increase the size and diversity of
validation data and provide a more robust evaluation of GOSAT
retrievals. Global-scale validation of satellite data remains
challenging and would be improved by increasing TCCON coverage.
BibTeX:
@article{guerlet13a,
  author = {Guerlet, S. and Butz, A. and Schepers, D. and Basu, S. and Hasekamp, O. P. and Kuze, A. and Yokota, T. and Blavier, J. -F. and Deutscher, N. M. and Griffith, D. W. T. and Hase, F. and Kyro, E. and Morino, I. and Sherlock, V. and Sussmann, R. and Galli, A. and Aben, I.},
  title = {Impact of aerosol and thin cirrus on retrieving and validating XCO2 from GOSAT shortwave infrared measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2013},
  volume = {118},
  number = {10},
  pages = {4887--4905},
  doi = {10.1002/jgrd.50332}
}
Halloran PR ({2012}), "Does atmospheric CO2 seasonality play an important role in governing the air-sea flux of CO2?", BIOGEOSCIENCES. Vol. {9}({6}), pp. 2311-2323.
Abstract: The amplitude, phase, and form of the seasonal cycle of atmospheric CO2
concentrations varies on many time and space scales (Peters et al.,
2007). Intra-annual CO2 variation is primarily driven by seasonal uptake
and release of CO2 by the terrestrial biosphere (Machta et al., 1977;
Buchwitz et al., 2007), with a small (Cadule et al., 2010; Heimann et
al., 1998), but potentially changing (Gorgues et al., 2010) contribution
from the ocean. Variability in the magnitude, spatial distribution, and
seasonal drivers of terrestrial net primary productivity (NPP) will be
induced by, amongst other factors, anthropogenic CO2 release (Keeling et
al., 1996), land-use change (Zimov et al., 1999) and planetary orbital
variability, and will lead to changes in CO2atm seasonality. Despite
CO2atm seasonality being a dynamic and prominent feature of the Earth
System, its potential to drive changes in the air-sea flux of CO2 has
not previously (to the best of my knowledge) been explored. It is
important that we investigate the impact of CO2atm seasonality change,
and the potential for carbon-cycle feedbacks to operate through the
modification of the CO2atm seasonal cycle, because the decision had been
made to prescribe CO2atm concentrations (rather than emissions) within
model simulations for the fifth IPCC climate assessment (Taylor et al.,
2009). In this study I undertake ocean-model simulations within which
different magnitude CO2atm seasonal cycles are prescribed. These
simulations allow me to examine the effect of a change in CO2atm
seasonal cycle magnitude on the air-sea CO2 flux. I then use an offline
model to isolate the drivers of the identified air-sea CO2 flux change,
and propose mechanisms by which this change may come about. Three
mechanisms are identified by which co-variability of the seasonal cycles
in atmospheric CO2 concentration, and seasonality in sea-ice extent,
wind-speed and ocean temperature, could potentially lead to changes in
the air-sea flux of CO2 at mid-to-high latitudes. The sea-ice driven
mechanism responds to an increase in CO2atm seasonality by pumping CO2
into the ocean, the wind-speed and solubility-driven mechanisms, by
releasing CO2 from the ocean (in a relative sense). The relative
importance of the mechanisms will be determined by, amongst other
variables, the seasonal extent of sea-ice. To capture the described
feedbacks within earth system models, CO2atm concentrations must be
allowed to evolve freely, forced only by anthropogenic emissions rather
than prescribed CO2atm concentrations; however, time-integrated ocean
simulations imply that the cumulative net air-sea flux could be at most
equivalent to a few ppm CO2atm. The findings presented here suggest
that, at least under pre-industrial conditions, the prescription of
CO2atm concentrations rather than emissions within simulations will have
little impact on the marine anthropogenic CO2 sink.
BibTeX:
@article{halloran12a,
  author = {Halloran, P. R.},
  title = {Does atmospheric CO2 seasonality play an important role in governing the air-sea flux of CO2?},
  journal = {BIOGEOSCIENCES},
  year = {2012},
  volume = {9},
  number = {6},
  pages = {2311--2323},
  doi = {10.5194/bg-9-2311-2012}
}
Haszpra L, Ramonet M, Schmidt M, Barcza Z, Patkai Z, Tarczay K, Yver C, Tarniewicz J and Ciais P ({2012}), "Variation of CO2 mole fraction in the lower free troposphere, in the boundary layer and at the surface", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({18}), pp. 8865-8875.
Abstract: Eight years of occasional flask air sampling and 3 years of frequent in
situ measurements of carbon dioxide (CO2) vertical profiles on board of
a small aircraft, over a tall tower greenhouse gases monitoring site in
Hungary are used for the analysis of the variations of vertical profile
of CO2 mole fraction. Using the airborne vertical profiles and the
measurements along the 115 m tall tower it is shown that the
measurements at the top of the tower estimate the mean boundary layer
CO2 mole fraction during the mid-afternoon fairly well, with an
underestimation of 0.27-0.85 mu mol mol(-1) in summer, and an
overestimation of 0.66-1.83 mu mol mol(-1) in winter. The seasonal cycle
of CO2 mole fraction is damped with elevation. While the amplitude of
the seasonal cycle is 28.5 mu mol mol(-1) at 10 m above the ground, it
is only 10.7 mu mol mol(-1) in the layer of 2500-3000 m corresponding to
the lower free atmosphere above the well-mixed boundary layer. The
maximum mole fraction in the layer of 2500-3000 m can be observed around
25 March on average, two weeks ahead of that of the marine boundary
layer reference (GLOBALVIEW). By contrast, close to the ground, the
maximum CO2 mole fraction is observed late December, early January. The
specific seasonal behavior is attributed to the climatology of vertical
mixing of the atmosphere in the Carpathian Basin.
BibTeX:
@article{haszpra12a,
  author = {Haszpra, L. and Ramonet, M. and Schmidt, M. and Barcza, Z. and Patkai, Zs and Tarczay, K. and Yver, C. and Tarniewicz, J. and Ciais, P.},
  title = {Variation of CO2 mole fraction in the lower free troposphere, in the boundary layer and at the surface},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2012},
  volume = {12},
  number = {18},
  pages = {8865--8875},
  doi = {10.5194/acp-12-8865-2012}
}
Hayashida S, Ono A, Yoshizaki S, Frankenberg C, Takeuchi W and Yan X ({2013}), "Methane concentrations over Monsoon Asia as observed by SCIAMACHY: Signals of methane emission from rice cultivation", REMOTE SENSING OF ENVIRONMENT., DEC, {2013}. Vol. {139}, pp. 246-256.
Abstract: We have analyzed the column-averaged CH4 concentration (xCH(4)) using
scanning imaging absorption spectrometer for atmospheric chartography
(SCIAMACHY) and compared the data with the bottom-up emission inventory
data sets and other satellite-derived indices such as the land-surface
water coverge (LSWC) and the normalized difference vegetation index
(NDVI). The geographical distribution of high CH4 values corresponds to
strong emissions from regions where rice is cultivated, as indicated in
the inventory maps. The Pearson's correlation coefficients (r) between
xCH(4) and the rice emission inventory data are observed to be greater
than similar to 0.6 over typical rice fields, with outstanding r-values
of similar to 0.8 in the Ganges Basin, Myanmar, and Thailand. This
suggests that the emission of CH4 from rice cultivation mainly controls
the seasonality of the CH4 concentration over such regions. The
correlation between xCH(4) and LSWC and NDVI is also as large as 0.6. In
Southeast Asia, the r-values of xCH4 with bottom-up inventory data that
includes all categories are not as high as those with the emission, as
estimated from the rice category only. This is indicative of the
relative importance of rice emissions among all other emission
categories in Southeast Asia. (C) 2013 Elsevier Inc. All rights
reserved.
BibTeX:
@article{hayashida13a,
  author = {Hayashida, S. and Ono, A. and Yoshizaki, S. and Frankenberg, C. and Takeuchi, W. and Yan, X.},
  title = {Methane concentrations over Monsoon Asia as observed by SCIAMACHY: Signals of methane emission from rice cultivation},
  journal = {REMOTE SENSING OF ENVIRONMENT},
  year = {2013},
  volume = {139},
  pages = {246--256},
  doi = {10.1016/j.rse.2013.08.008}
}
Hayes DJ, Turner DP, Stinson G, McGuire AD, Wei Y, West TO, Heath LS, Dejong B, McConkey BG, Birdsey RA, Kurz WA, Jacobson AR, Huntzinger DN, Pan Y, Mac Post W and Cook RB ({2012}), "Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data", GLOBAL CHANGE BIOLOGY., APR, {2012}. Vol. {18}({4}), pp. 1282-1299.
Abstract: We develop an approach for estimating net ecosystem exchange (NEE) using
inventory-based information over North America (NA) for a recent 7-year
period (ca. 2000-2006). The approach notably retains information on the
spatial distribution of NEE, or the vertical exchange between land and
atmosphere of all non-fossil fuel sources and sinks of CO2, while
accounting for lateral transfers of forest and crop products as well as
their eventual emissions. The total NEE estimate of a -327 similar to
+/-similar to 252 similar to TgC similar to yr-1 sink for NA was driven
primarily by CO2 uptake in the Forest Lands sector (-248 similar to TgC
similar to yr-1), largely in the Northwest and Southeast regions of the
US, and in the Crop Lands sector (-297 similar to TgC similar to yr-1),
predominantly in the Midwest US states. These sinks are counteracted by
the carbon source estimated for the Other Lands sector (+218 similar to
TgC similar to yr-1), where much of the forest and crop products are
assumed to be returned to the atmosphere (through livestock and human
consumption). The ecosystems of Mexico are estimated to be a small net
source (+18 similar to TgC similar to yr-1) due to land use change
between 1993 and 2002. We compare these inventory-based estimates with
results from a suite of terrestrial biosphere and atmospheric inversion
models, where the mean continental-scale NEE estimate for each ensemble
is -511 similar to TgC similar to yr-1 and -931 similar to TgC similar
to yr-1, respectively. In the modeling approaches, all sectors,
including Other Lands, were generally estimated to be a carbon sink,
driven in part by assumed CO2 fertilization and/or lack of consideration
of carbon sources from disturbances and product emissions. Additional
fluxes not measured by the inventories, although highly uncertain, could
add an additional -239 similar to TgC similar to yr-1 to the
inventory-based NA sink estimate, thus suggesting some convergence with
the modeling approaches.
BibTeX:
@article{hayes12a,
  author = {Hayes, Daniel J. and Turner, David P. and Stinson, Graham and McGuire, A. David and Wei, Yaxing and West, Tristram O. and Heath, Linda S. and Dejong, Bernardus and McConkey, Brian G. and Birdsey, Richard A. and Kurz, Werner A. and Jacobson, Andrew R. and Huntzinger, Deborah N. and Pan, Yude and Mac Post, W. and Cook, Robert B.},
  title = {Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2012},
  volume = {18},
  number = {4},
  pages = {1282--1299},
  doi = {10.1111/j.1365-2486.2011.02627.x}
}
Hayes D and Turner D (2012), "The need for ``apples‐to‐apples'' comparisons of carbon dioxide source and sink estimates", Eos, Transactions American Geophysical Union. Vol. 93(41), pp. 404-405.
BibTeX:
@article{hayes12b,
  author = {Hayes, Daniel and Turner, David},
  title = {The need for ``apples‐to‐apples'' comparisons of carbon dioxide source and sink estimates},
  journal = {Eos, Transactions American Geophysical Union},
  year = {2012},
  volume = {93},
  number = {41},
  pages = {404--405},
  doi = {10.1029/2012EO410007/full}
}
Hazan L, Tarniewicz J, Ramonet M, Laurent O and Abbaris A ({2016}), "Automatic processing of atmospheric CO2 and CH4 mole fractions at the ICOS Atmosphere Thematic Centre", ATMOSPHERIC MEASUREMENT TECHNIQUES., SEP 22, {2016}. Vol. {9}({9}), pp. 4719-4736.
Abstract: The Integrated Carbon Observation System Atmosphere Thematic Centre
(ICOS ATC) automatically processes atmospheric greenhouse gases mole
fractions of data coming from sites of the ICOS network. Daily
transferred raw data files are automatically processed and archived.
Data are stored in the ICOS atmospheric database, the backbone of the
system, which has been developed with an emphasis on the traceability of
the data processing. Many data products, updated daily, explore the data
through different angles to support the quality control of the dataset
performed by the principal operators in charge of the instruments. The
automatic processing includes calibration and water vapor corrections as
described in the paper. The mole fractions calculated in near-real time
(NRT) are automatically revaluated as soon as a new instrument
calibration is processed or when the station supervisors perform quality
control. By analyzing data from 11 sites, we determined that the average
calibration corrections are equal to 1.7 +/- 0.3 mu mol mol(-1) for CO2
and 2.8 +/- 3 nmol mol(-1) for CH4. These biases are important to
correct to avoid artificial gradients between stations that could lead
to error in flux estimates when using atmospheric inversion techniques.
We also calculated that the average drift between two successive
calibrations separated by 15 days amounts to +/- 0.05 mu mol mol(-1) and
+/- 0.7 nmol mol(-1) for CO2 and CH4, respectively. Outliers are
generally due to errors in the instrument configuration and can be
readily detected thanks to the data products provided by the ATC.
Several developments are still ongoing to improve the processing,
including automated spike detection and calculation of time-varying
uncertainties.
BibTeX:
@article{hazan16a,
  author = {Hazan, Lynn and Tarniewicz, Jerome and Ramonet, Michel and Laurent, Olivier and Abbaris, Amara},
  title = {Automatic processing of atmospheric CO2 and CH4 mole fractions at the ICOS Atmosphere Thematic Centre},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {9},
  pages = {4719--4736},
  doi = {10.5194/amt-9-4719-2016}
}
He Z, Zeng Z-C, Lei L, Bie N and Yang S ({2017}), "A Data-Driven Assessment of Biosphere-Atmosphere Interaction Impact on Seasonal Cycle Patterns of XCO2 Using GOSAT and MODIS Observations", REMOTE SENSING., MAR, {2017}. Vol. {9}({3})
Abstract: Using measurements of the column-averaged CO2 dry air mole fraction
(XCO2) from GOSAT and biosphere parameters, including normalized
difference vegetation index (NDVI), enhanced vegetation index (EVI),
leaf area index (LAI), gross primary production (GPP), and land surface
temperature (LST) from MODIS, this study proposes a data-driven approach
to assess the impacts of terrestrial biosphere activities on the
seasonal cycle pattern of XCO2. A unique global land mapping dataset of
XCO2 with a resolution of 1 degrees by 1 degrees in space, and three
days in time, from June 2009 to May 2014, which facilitates the
assessment at a fine scale, is first produced from GOSAT XCO2
retrievals. We then conduct a statistical fitting method to obtain the
global map of seasonal cycle amplitudes (SCA) of XCO2 and NDVI, and
implement correlation analyses of seasonal variation between XCO2 and
the vegetation parameters. As a result, the spatial distribution of XCO2
SCA decreases globally with latitude from north to south, which is in
good agreement with that of simulated XCO2 from CarbonTracker. The
spatial pattern of XCO2 SCA corresponds well to the vegetation seasonal
activity revealed by NDVI, with a strong correlation coefficient of 0.74
in the northern hemisphere (NH). Some hotspots in the subtropical areas,
including Northern India (with SCA of 8.68 +/- 0.49 ppm on average) and
Central Africa (with SCA of 8.33 +/- 0.25 ppm on average), shown by
satellite measurements, but missed by model simulations, demonstrate the
advantage of satellites in observing the biosphere-atmosphere
interactions at local scales. Results from correlation analyses between
XCO2 and NDVI, EVI, LAI, or GPP show a consistent spatial distribution,
and NDVI and EVI have stronger negative correlations over all latitudes.
This may suggest that NDVI and EVI can be better vegetation parameters
in characterizing the seasonal variations of XCO2 and its driving
terrestrial biosphere activities. We, furthermore, present the global
distribution of phase lags of XCO2 compared to NDVI in seasonal
variation, which, to our knowledge, is the first such map derived from a
completely data-driven approach using satellite observations. The impact
of retrieval error of GOSAT data on the mapping data, especially over
high-latitude areas, is further discussed. Results from this study
provide reference for better understanding the distribution of the
strength of carbon sink by terrestrial ecosystems and utilizing remote
sensing data in assessing the impact of biosphere-atmosphere
interactions on the seasonal cycle pattern of atmospheric CO2 columns.
BibTeX:
@article{he17a,
  author = {He, Zhonghua and Zeng, Zhao-Cheng and Lei, Liping and Bie, Nian and Yang, Shaoyuan},
  title = {A Data-Driven Assessment of Biosphere-Atmosphere Interaction Impact on Seasonal Cycle Patterns of XCO2 Using GOSAT and MODIS Observations},
  journal = {REMOTE SENSING},
  year = {2017},
  volume = {9},
  number = {3},
  doi = {10.3390/rs9030251}
}
He Z, Lei L, Welp LR, Zeng Z-C, Bie N, Yang S and Liu L (2018), "Detection of Spatiotemporal Extreme Changes in Atmospheric CO2 Concentration Based on Satellite Observations", Remote Sensing. Vol. 10
BibTeX:
@article{he18a,
  author = {Zhonghua He and Liping Lei and Lisa R. Welp and Zhao-Cheng Zeng and Nian Bie and Shaoyuan Yang and Liangyun Liu},
  title = {Detection of Spatiotemporal Extreme Changes in Atmospheric CO2 Concentration Based on Satellite Observations},
  journal = {Remote Sensing},
  year = {2018},
  volume = {10},
  url = {https://www.mdpi.com/2072-4292/10/6/839}
}
He W, Ju W, Schwaim CR, Sippel S, Wu X, He Q, Song L, Zhang C, Li J, Sitch S, Viovy N, Friedlingstein P and Jain AK ({2018}), "Large-Scale Droughts Responsible for Dramatic Reductions of Terrestrial Net Carbon uptake Over North America in 2011 and 2012", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., JUL, {2018}. Vol. {123}({7}), pp. {2053-2071}.
Abstract: Recently, severe droughts that occurred in North America are likely to
have impacted its terrestrial carbon sink. However, process-based
understanding of how meteorological conditions prior to the onset of
drought, for instance warm or cold springs, affect drought-induced
carbon cycle effects remains scarce. Here we assess and compare the
response of terrestrial carbon fluxes to summer droughts in 2011 and
2012 characterized by contrasting spring conditions. The analysis is
based on a comprehensive ensemble of carbon cycle models, including
FLUXCOM, TRENDY v5, SiBCASA, CarbonTracker Europe, and CarbonTracker,
and emerging Earth observations. In 2011, large reductions of net
ecosystem production (NEP; -0.24 +/- 0.17 Pg C/year) are due to
decreased gross primary production (-0.17 +/- 0.18 Pg C/year) and
slightly increased ecosystem respiration (+0.07 +/- 0.17 Pg C/year).
Conversely, in 2012, NEP reductions (-0.17 +/- 0.25 Pg C/year) are
attributed to a larger increase of ecosystem respiration (+0.48 +/- 0.27
Pg C/year) than gross primary production (+0.31 +/- 0.29 Pg C/year),
induced predominantly by an extra warmer spring prior to summer drought.
Two temperate ecoregions crops/agriculture and the grass/shrubs
contribute largest to these reductions and also dominate the interannual
variations of NEP during 2007-2014. Moreover, the warming spring
compensated largely the negative carbon anomaly due to summer drought,
consistent with earlier studies; however, the compensation occurred only
in some specific ecoregions. Overall, our analysis offers a refined view
on recent carbon cycle variability and extremes in North America. It
corroborates earlier results but also highlights differences with
respect to ecoregion-specific carbon cycle responses to drought and
heat.
BibTeX:
@article{he18b,
  author = {He, Wei and Ju, Weimin and Schwaim, Christopher R. and Sippel, Sebastian and Wu, Xiaocui and He, Qiaoning and Song, Lian and Zhang, Chunhua and Li, Jing and Sitch, Stephen and Viovy, Nicolas and Friedlingstein, Pierre and Jain, Atul K.},
  title = {Large-Scale Droughts Responsible for Dramatic Reductions of Terrestrial Net Carbon uptake Over North America in 2011 and 2012},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2018},
  volume = {123},
  number = {7},
  pages = {2053-2071},
  doi = {{10.1029/2018JG004520}}
}
He W, van der Velde IR, Andrews AE, Sweeney C, Miller J, Tans P, van der Laan-Luijkx IT, Nehrkorn T, Mountain M, Ju W, Peters W and Chen H (2018), "CTDAS-Lagrange v1. 0: A high-resolution data assimilation system for regional carbon dioxide observations", GEOSCIENTIFIC MODEL DEVELOPMENT., AUG, 2018. Vol. 11, pp. 3515-3536.
BibTeX:
@article{he18c,
  author = {Wei He and Ivar R. van der Velde and Arlyn E. Andrews and Colm Sweeney and John Miller and Pieter Tans and Ingrid T. van der Laan-Luijkx and Thomas Nehrkorn and Marikate Mountain and Weimin Ju and Wouter Peters and Huilin Chen},
  title = {CTDAS-Lagrange v1. 0: A high-resolution data assimilation system for regional carbon dioxide observations},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2018},
  volume = {11},
  pages = {3515-3536},
  url = {https://www.geosci-model-dev.net/11/3515/2018/gmd-11-3515-2018.pdf}
}
Helbig M, Chasmer LE, Desai AR, Kljun N, Quinton WL and Sonnentag O ({2017}), "Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape", GLOBAL CHANGE BIOLOGY., AUG, {2017}. Vol. {23}({8}), pp. 3231-3248.
Abstract: In the sporadic permafrost zone of northwestern Canada, boreal forest
carbon dioxide (CO2) fluxes will be altered directly by climate change
through changing meteorological forcing and indirectly through changes
in landscape functioning associated with thaw-induced collapse-scar bog
(` wetland') expansion. However, their combined effect on
landscape-scale net ecosystem CO2 exchange (NEELAND), resulting from
changing gross primary productivity (GPP) and ecosystem respiration
(ER), remains unknown. Here, we quantify indirect land cover change
impacts on NEELAND and direct climate change impacts on modeled
temperature-and light-limited NEELAND of a boreal forestwetland
landscape. Using nested eddy covariance flux towers, we find both GPP
and ER to be larger at the landscape compared to the wetland level.
However, annual NEELAND (-20 g C m(-2)) and wetland NEE (-24 g C m(-2))
were similar, suggesting negligible wetland expansion effects on
NEELAND. In contrast, we find non-negligible direct climate change
impacts when modeling NEELAND using projected air temperature and
incoming shortwave radiation. At the end of the 21st century, modeled
GPP mainly increases in spring and fall due to reduced temperature
limitation, but becomes more frequently light-limited in fall. In a
warmer climate, ER increases year-round in the absence of moisture
stress resulting in net CO2 uptake increases in the shoulder seasons and
decreases during the summer. Annually, landscape net CO2 uptake is
projected to decline by 25 +/- 14 g C m(-2) for a moderate and 103 +/-
38 g C m(-2) for a high warming scenario, potentially reversing recently
observed positive net CO2 uptake trends across the boreal biome. Thus,
even without moisture stress, net CO2 uptake of boreal forest-wetland
landscapes may decline, and ultimately, these landscapes may turn into
net CO2 sources under continued anthropogenic CO2 emissions. We conclude
that NEELAND changes are more likely to be driven by direct climate
change rather than by indirect land cover change impacts.
BibTeX:
@article{helbig17a,
  author = {Helbig, Manuel and Chasmer, Laura E. and Desai, Ankur R. and Kljun, Natascha and Quinton, William L. and Sonnentag, Oliver},
  title = {Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2017},
  volume = {23},
  number = {8},
  pages = {3231--3248},
  doi = {10.1111/gcb.13638}
}
Hernandez-Carrasco I, Sudre J, Garcon V, Yahia H, Garbe C, Paulmier A, Dewitte B, Illig S, Dadou I, Gonzalez-Davila M and Santana-Casiano JM ({2015}), "Reconstruction of super-resolution ocean pCO(2) and air-sea fluxes of CO2 from satellite imagery in the southeastern Atlantic", BIOGEOSCIENCES. Vol. {12}({17}), pp. 5229-5245.
Abstract: An accurate quantification of the role of the ocean as source/sink of
greenhouse gases (GHGs) requires to access the high-resolution of the
GHG air-sea flux at the interface. In this paper we present a novel
method to reconstruct maps of surface ocean partial pressure of CO2
(pCO(2)) and air-sea CO2 fluxes at super resolution (4 km, i.e., 1/32
degrees at these latitudes) using sea surface temperature (SST) and
ocean color (OC) data at this resolution, and CarbonTracker CO2 fluxes
data at low resolution (110 km). Inference of super-resolution pCO(2)
and air-sea CO2 fluxes is performed using novel nonlinear signal
processing methodologies that prove efficient in the context of
oceanography. The theoretical background comes from the microcanonical
multi-fractal formalism which unlocks the geometrical determination of
cascading properties of physical intensive variables. As a consequence,
a multi-resolution analysis performed on the signal of the so-called
singularity exponents allows for the correct and near optimal
cross-scale inference of GHG fluxes, as the inference suits the
geometric realization of the cascade. We apply such a methodology to the
study offshore of the Benguela area. The inferred representation of
oceanic partial pressure of CO2 improves and enhances the description
provided by CarbonTracker, capturing the small-scale variability. We
examine different combinations of ocean color and sea surface
temperature products in order to increase the number of valid points and
the quality of the inferred pCO(2) field. The methodology is validated
using in situ measurements by means of statistical errors. We find that
mean absolute and relative errors in the inferred values of pCO(2) with
respect to in situ measurements are smaller than for CarbonTracker.
BibTeX:
@article{hernandez-carrasco15a,
  author = {Hernandez-Carrasco, I. and Sudre, J. and Garcon, V. and Yahia, H. and Garbe, C. and Paulmier, A. and Dewitte, B. and Illig, S. and Dadou, I. and Gonzalez-Davila, M. and Santana-Casiano, J. M.},
  title = {Reconstruction of super-resolution ocean pCO(2) and air-sea fluxes of CO2 from satellite imagery in the southeastern Atlantic},
  journal = {BIOGEOSCIENCES},
  year = {2015},
  volume = {12},
  number = {17},
  pages = {5229--5245},
  doi = {10.5194/bg-12-5229-2015}
}
Hernandez-Carrasco I, Garcon V, Sudre J, Garbe C and Yahia H ({2018}), "Increasing the Resolution of Ocean pCO(2) Maps in the South Eastern Atlantic Ocean Merging Multifractal Satellite-Derived Ocean Variables", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., NOV, {2018}. Vol. {56}({11}), pp. {6596-6610}.
Abstract: A new methodology has been developed in order to improve the description
of the spatial and temporal variability of not well-resolved oceanic
variables from other well-observed high-resolution oceanic variables.
The method is based on the cross-scale inference of information,
incorporating the common features of different multifractal
high-resolution variables into a coarser one. An exercise of validation
of the methodology has been performed based on the outputs of coupled
physical-biogeochemical Regional Ocean Modeling System adapted to the
eastern boundary upwelling systems at two spatial resolutions. Once the
algorithm has been proved to he effective in increasing the spatial
resolution of modeled partial pressure of CO2 at the surface ocean
(pCO(2)), we have investigated the capability of our methodology when it
is applied to remote sensing data, focusing on the improvement of the
temporal description. In this regard, we have inferred daily pCO(2) maps
at high resolution (4 km, i.e., 1/24 degrees) fusing monthly pCO(2) data
at low resolution (100 kin, i.e., 1 degrees) with the small-scale
features contained in daily high-resolution maps of satellite sea
surface temperature and Chlorophyll-a. The algorithm has been applied to
the South Eastern Atlantic Ocean opening the possibility to obtain an
accurate quantification of the CO2 fluxes in relevant coastal regions,
such as the eastern boundary upwelling systems. Outputs of our algorithm
have been compared with in situ measurements, showing that daily maps
inferred from monthly products are in average 6 mu atm closer to the in
situ values than the original coarser monthly maps. Furthermore, values
of pCO(2) have been improved in points close to the coast with respect
to the original input data.
BibTeX:
@article{hernandez-carrasco18a,
  author = {Hernandez-Carrasco, Ismael and Garcon, Veronique and Sudre, Joel and Garbe, Christoph and Yahia, Hussein},
  title = {Increasing the Resolution of Ocean pCO(2) Maps in the South Eastern Atlantic Ocean Merging Multifractal Satellite-Derived Ocean Variables},
  journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
  year = {2018},
  volume = {56},
  number = {11},
  pages = {6596-6610},
  doi = {{10.1109/TGRS.2018.2840526}}
}
Heymann J, Schneising O, Reuter M, Buchwitz M, Rozanov VV, Velazco VA, Bovensmann H and Burrows JP ({2012}), "SCIAMACHY WFM-DOAS XCO2: comparison with CarbonTracker XCO2 focusing on aerosols and thin clouds", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({8}), pp. 1935-1952.
Abstract: Carbon dioxide (CO2) is the most important greenhouse gas whose
atmospheric loading has been significantly increased by anthropogenic
activity leading to global warming. Accurate measurements and models are
needed in order to reliably predict our future climate. This, however,
has challenging requirements. Errors in measurements and models need to
be identified and minimised.
In this context, we present a comparison between satellite-derived
column-averaged dry air mole fractions of CO2, denoted XCO2, retrieved
from SCIAMACHY/ENVISAT using the WFM-DOAS (weighting function modified
differential optical absorption spectroscopy) algorithm, and output from
NOAA's global CO2 modelling and assimilation system CarbonTracker. We
investigate to what extent differences between these two data sets are
influenced by systematic retrieval errors due to aerosols and
unaccounted clouds. We analyse seven years of SCIAMACHY WFM-DOAS version
2.1 retrievals (WFMDv2.1) using CarbonTracker version 2010.
We investigate to what extent the difference between SCIAMACHY and
CarbonTracker XCO2 are temporally and spatially correlated with global
aerosol and cloud data sets. For this purpose, we use a global aerosol
data set generated within the European GEMS project, which is based on
assimilated MODIS satellite data. For clouds, we use a data set derived
from CALIOP/CALIPSO.
We find significant correlations of the SCIAMACHY minus CarbonTracker
XCO2 difference with thin clouds over the Southern Hemisphere. The
maximum temporal correlation we find for Darwin, Australia (r(2) =
54. Large temporal correlations with thin clouds are also observed
over other regions of the Southern Hemisphere (e. g. 43% for South
America and 31% for South Africa). Over the Northern Hemisphere the
temporal correlations are typically much lower. An exception is India,
where large temporal correlations with clouds and aerosols have also
been found. For all other regions the temporal correlations with aerosol
are typically low. For the spatial correlations the picture is less
clear. They are typically low for both aerosols and clouds, but
depending on region and season, they may exceed 30% (the maximum value
of 46% has been found for Darwin during September to November).
Overall we find that the presence of thin clouds can potentially explain
a significant fraction of the difference between SCIAMACHY WFMDv2.1 XCO2
and CarbonTracker over the Southern Hemisphere. Aerosols appear to be
less of a problem. Our study indicates that the quality of the satellite
derived XCO2 will significantly benefit from a reduction of scattering
related retrieval errors at least for the Southern Hemisphere.
BibTeX:
@article{heymann12a,
  author = {Heymann, J. and Schneising, O. and Reuter, M. and Buchwitz, M. and Rozanov, V. V. and Velazco, V. A. and Bovensmann, H. and Burrows, J. P.},
  title = {SCIAMACHY WFM-DOAS XCO2: comparison with CarbonTracker XCO2 focusing on aerosols and thin clouds},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2012},
  volume = {5},
  number = {8},
  pages = {1935--1952},
  doi = {10.5194/amt-5-1935-2012}
}
Heymann J, Bovensmann H, Buchwitz M, Burrows JP, Deutscher NM, Notholt J, Rettinger M, Reuter M, Schneising O, Sussmann R and Warneke T ({2012}), "SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({10}), pp. 2375-2390.
Abstract: Global observations of column-averaged dry air mole fractions of carbon
dioxide (CO2), denoted by XCO2, retrieved from SCIAMACHY on-board
ENVISAT can provide important and missing global information on the
distribution and magnitude of regional CO2 surface fluxes. This
application has challenging precision and accuracy requirements.
In a previous publication (Heymann et al., 2012), it has been shown by
analysing seven years of SCIAMACHY WFM-DOAS XCO2 (WFMDv2.1) that
unaccounted thin cirrus clouds can result in significant errors.
In order to enhance the quality of the SCIAMACHY XCO2 data product, we
have developed a new version of the retrieval algorithm (WFMDv2.2),
which is described in this manuscript. It is based on an improved cloud
filtering and correction method using the 1.4 mu m strong water vapour
absorption and 0.76 mu m O-2-A bands. The new algorithm has been used to
generate a SCIAMACHY XCO2 data set covering the years 2003-2009.
The new XCO2 data set has been validated using ground-based observations
from the Total Carbon Column Observing Network (TCCON). The validation
shows a significant improvement of the new product (v2.2) in comparison
to the previous product (v2.1). For example, the standard deviation of
the difference to TCCON at Darwin, Australia, has been reduced from 4
ppm to 2 ppm. The monthly regional-scale scatter of the data (defined as
the mean intra-monthly standard deviation of all quality filtered XCO2
retrievals within a radius of 350 km around various locations) has also
been reduced, typically by a factor of about 1.5. Overall, the
validation of the new WFMDv2.2 XCO2 data product can be summarised by a
single measurement precision of 3.8 ppm, an estimated regional-scale
(radius of 500 km) precision of monthly averages of 1.6 ppm and an
estimated regional-scale relative accuracy of 0.8 ppm.
In addition to the comparison with the limited number of TCCON sites, we
also present a comparison with NOAA's global CO2 modelling and
assimilation system Carbon-Tracker. This comparison also shows
significant improvements especially over the Southern Hemisphere.
BibTeX:
@article{heymann12b,
  author = {Heymann, J. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Deutscher, N. M. and Notholt, J. and Rettinger, M. and Reuter, M. and Schneising, O. and Sussmann, R. and Warneke, T.},
  title = {SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2012},
  volume = {5},
  number = {10},
  pages = {2375--2390},
  doi = {10.5194/amt-5-2375-2012}
}
Heymann J (2013), "Satellite measurements of carbon dioxide: impact and consideration of atmospheric scattering on the data retrieval and interpretation". Thesis at: Universität Bremen.
BibTeX:
@phdthesis{heymann13a,
  author = {Heymann, Jens},
  title = {Satellite measurements of carbon dioxide: impact and consideration of atmospheric scattering on the data retrieval and interpretation},
  school = {Universität Bremen},
  year = {2013},
  url = {https://d-nb.info/1072047985/34}
}
Heymann J, Reuter M, Hilker M, Buchwitz M, Schneising O, Bovensmann H, Burrows JP, Kuze A, Suto H, Deutscher NM, Dubey MK, Griffith DWT, Hase F, Kawakami S, Kivi R, Morino I, Petri C, Roehl C, Schneider M, Sherlock V, Sussmann R, Velazco VA, Warneke T and Wunch D ({2015}), "Consistent satellite XCO2 retrievals from SCIAMACHY and GOSAT using the BESD algorithm", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({7}), pp. 2961-2980.
Abstract: Consistent and accurate long-term data sets of global atmospheric
concentrations of carbon dioxide (CO2) are required for carbon cycle and
climate-related research. However, global data sets based on satellite
observations may suffer from inconsistencies originating from the use of
products derived from different satellites as needed to cover a long
enough time period. One reason for inconsistencies can be the use of
different retrieval algorithms. We address this potential issue by
applying the same algorithm, the Bremen Optimal Estimation DOAS (BESD)
algorithm, to different satellite instruments, SCIAMACHY on-board
ENVISAT (March 2002-April 2012) and TANSO-FTS onboard GOSAT (launched in
January 2009), to retrieve XCO2, the column-averaged dry-air mole
fraction of CO2. BESD has been initially developed for SCIAMACHY XCO2
retrievals. Here, we present the first detailed assessment of the new
GOSAT BESD XCO2 product. GOSAT BESD XCO2 is a product generated and
delivered to the MACC project for assimilation into ECMWF's Integrated
Forecasting System. We describe the modifications of the BESD algorithm
needed in order to retrieve XCO2 from GOSAT and present de-tailed
comparisons with ground-based observations of XCO2 from the Total Carbon
Column Observing Network (TCCON). We discuss detailed comparison results
between all three XCO2 data sets (SCIAMACHY, GOSAT and TCCON). The
comparison results demonstrate the good consistency between SCIAMACHY
and GOSAT XCO2. For example, we found a mean difference for daily
averages of -0.60 +/- 1.56 ppm (mean difference +/- standard deviation)
for GOSAT-SCIAMACHY (linear correlation coefficient r = 0.82), -0.34 +/-
1.37 ppm (r = 0.86) for GOSAT-TCCON and 0.10 +/- 1.79 ppm (r = 0.75) for
SCIAMACHY-TCCON. The remaining differences between GOSAT and SCIAMACHY
are likely due to non-perfect collocation (+/- 2 h, 10 degrees x 10
degrees around TCCON sites), i.e. the observed air masses are not
exactly identical but likely also due to a still non-perfect BESD
retrieval algorithm, which will be continuously improved in the future.
Our overarching goal is to generate a satellite-derived XCO2 data set
appropriate for climate and carbon cycle research covering the longest
possible time period. We therefore also plan to extend the existing
SCIAMACHY and GOSAT data set discussed here by also using data from
other missions (e.g. OCO-2, GOSAT-2, CarbonSat) in the future.
BibTeX:
@article{heymann15a,
  author = {Heymann, J. and Reuter, M. and Hilker, M. and Buchwitz, M. and Schneising, O. and Bovensmann, H. and Burrows, J. P. and Kuze, A. and Suto, H. and Deutscher, N. M. and Dubey, M. K. and Griffith, D. W. T. and Hase, F. and Kawakami, S. and Kivi, R. and Morino, I. and Petri, C. and Roehl, C. and Schneider, M. and Sherlock, V. and Sussmann, R. and Velazco, V. A. and Warneke, T. and Wunch, D.},
  title = {Consistent satellite XCO2 retrievals from SCIAMACHY and GOSAT using the BESD algorithm},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {7},
  pages = {2961--2980},
  doi = {10.5194/amt-8-2961-2015}
}
Heymann J, Reuter M, Buchwitz M, Schneising O, Bovensmann H, Burrows JP, Massart S, Kaiser JW and Crisp D ({2017}), "CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations", GEOPHYSICAL RESEARCH LETTERS., FEB 16, {2017}. Vol. {44}({3}), pp. 1537-1544.
Abstract: Indonesia experienced an exceptional number of fires in 2015 as a result
of droughts related to the recent El Nio event and human activities.
These fires released large amounts of carbon dioxide (CO2) into the
atmosphere. Emission databases such as the Global Fire Assimilation
System version 1.2 and the Global Fire Emission Database version 4s
estimated the CO2 emission to be approximately 1100 MtCO(2) in the time
period from July to November 2015. This emission was indirectly
estimated by using parameters like burned area, fire radiative power,
and emission factors. In the study presented in this paper, we estimate
the Indonesian fire CO2 emission by using the column-averaged dry air
mole fraction of CO2, XCO2, derived from measurements of the Orbiting
Carbon Observatory-2 satellite mission. The estimated CO2 emission is
748 +/- 209 MtCO(2), which is about 30% lower than provided by the
emission databases.
BibTeX:
@article{heymann17a,
  author = {Heymann, J. and Reuter, M. and Buchwitz, M. and Schneising, O. and Bovensmann, H. and Burrows, J. P. and Massart, S. and Kaiser, J. W. and Crisp, D.},
  title = {CO2 emission of Indonesian fires in 2015 estimated from satellite-derived atmospheric CO2 concentrations},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2017},
  volume = {44},
  number = {3},
  pages = {1537--1544},
  doi = {10.1002/2016GL072042}
}
Hilton TW (2011), "Spatial structure in North American terrestrial biological carbon fluxes and flux model errors evaluated with a simple land surface model". Thesis at: The Pennsylvania State University.
BibTeX:
@phdthesis{hilton11a,
  author = {Hilton, Timothy William},
  title = {Spatial structure in North American terrestrial biological carbon fluxes and flux model errors evaluated with a simple land surface model},
  school = {The Pennsylvania State University},
  year = {2011},
  url = {http://search.proquest.com/openview/ad1f013a7f8d52fe468d7ba861602aa1/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Hilton TW, Davis KJ, Keller K and Urban NM ({2013}), "Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals", BIOGEOSCIENCES. Vol. {10}({7}), pp. 4607-4625.
Abstract: We evaluate spatial structure in North American CO2 flux observations
using a simple diagnostic land surface model. The vegetation
photosynthesis respiration model (VPRM) calculates net ecosystem
exchange (NEE) using locally observed temperature and photosynthetically
active radiation (PAR) along with satellite-derived phenology and
moisture. We use observed NEE from a group of 65 North American eddy
covariance tower sites spanning North America to estimate VPRM
parameters for these sites. We investigate spatial coherence in regional
CO2 fluxes at several different time scales by using geostatistical
methods to examine the spatial structure of model-data residuals. We
find that persistent spatial structure does exist in the model-data
residuals at a length scale of approximately 400 km (median 402 km, mean
712 km, standard deviation 931 km). This spatial structure defines a
flux-tower-based VPRM residual covariance matrix. The residual
covariance matrix is useful in constructing prior fluxes for atmospheric
CO2 concentration inversion calculations, as well as for constructing a
VPRM North American CO2 flux map optimized to eddy covariance
observations. Finally (and secondarily), the estimated VPRM parameter
values do not separate clearly by plant functional type (PFT). This
calls into question whether PFTs can successfully partition ecosystems'
fundamental ecological drivers when the viewing lens is a simple model.
BibTeX:
@article{hilton13a,
  author = {Hilton, T. W. and Davis, K. J. and Keller, K. and Urban, N. M.},
  title = {Improving North American terrestrial CO2 flux diagnosis using spatial structure in land surface model residuals},
  journal = {BIOGEOSCIENCES},
  year = {2013},
  volume = {10},
  number = {7},
  pages = {4607--4625},
  doi = {10.5194/bg-10-4607-2013}
}
Hilton TW, Davis KJ and Keller K ({2014}), "Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals", BIOGEOSCIENCES. Vol. {11}({2}), pp. 217-235.
Abstract: Global terrestrial atmosphere-ecosystem carbon dioxide fluxes are well
constrained by the concentration and isotopic composition of atmospheric
carbon dioxide. In contrast, considerable uncertainty persists
surrounding regional contributions to the net global flux as well as the
impacts of atmospheric and biological processes that drive the net flux.
These uncertainties severely limit our ability to make confident
predictions of future terrestrial biological carbon fluxes. Here we use
a simple light-use efficiency land surface model (the Vegetation
Photosynthesis Respiration Model, VPRM) driven by remotely sensed
temperature, moisture, and phenology to diagnose North American gross
ecosystem exchange (GEE), ecosystem respiration, and net ecosystem
exchange (NEE) for the period 2001 to 2006. We optimize VPRM parameters
to eddy covariance (EC) NEE observations from 65 North American FluxNet
sites. We use a separate set of 27 cross-validation FluxNet sites to
evaluate a range of spatial and temporal resolutions for parameter
estimation. With these results we demonstrate that different spatial and
temporal groupings of EC sites for parameter estimation achieve similar
sum of squared residuals values through radically different spatial
patterns of NEE. We also derive a regression model to estimate observed
VPRM errors as a function of VPRM NEE, temperature, and precipitation.
Because this estimate is based on model-observation residuals it is
comprehensive of all the error sources present in modeled fluxes. We
find that 1 km interannual variability in VPRM NEE is of similar
magnitude to estimated 1 km VPRM NEE errors.
BibTeX:
@article{hilton14a,
  author = {Hilton, T. W. and Davis, K. J. and Keller, K.},
  title = {Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals},
  journal = {BIOGEOSCIENCES},
  year = {2014},
  volume = {11},
  number = {2},
  pages = {217--235},
  doi = {10.5194/bg-11-217-2014}
}
Houweling S, Aben I, Breon F-M, Chevallier F, Deutscher N, Engelen R, Gerbig C, Griffith D, Hungershoefer K, Macatangay R, Marshall J, Notholt J, Peters W and Serrar S ({2010}), "The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({20}), pp. 9981-9992.
Abstract: This study presents a synthetic model intercomparison to investigate the
importance of transport model errors for estimating the sources and
sinks of CO2 using satellite measurements. The experiments were designed
for testing the potential performance of the proposed CO2 lidar A-SCOPE,
but also apply to other space borne missions that monitor total column
CO2. The participating transport models IFS, LMDZ, TM3, and TM5 were run
in forward and inverse mode using common a priori CO2 fluxes and initial
concentrations. Forward simulations of column averaged CO2 (xCO(2))
mixing ratios vary between the models by sigma = 0.5 ppm over the
continents and sigma = 0.27 ppm over the oceans. Despite the fact that
the models agree on average on the sub-ppm level, these modest
differences nevertheless lead to significant discrepancies in the
inverted fluxes of 0.1 PgC/yr per 10(6) km(2) over land and 0.03 PgC/yr
per 10(6) km(2) over the ocean. These transport model induced flux
uncertainties exceed the target requirement that was formulated for the
A-SCOPE mission of 0.02 PgC/yr per 10(6) km(2), and could also limit the
overall performance of other CO2 missions such as GOSAT. A variable, but
overall encouraging agreement is found in comparison with FTS
measurements at Park Falls, Darwin, Spitsbergen, and Bremen, although
systematic differences are found exceeding the 0.5 ppm level. Because of
this, our estimate of the impact of transport model uncerainty is likely
to be conservative. It is concluded that to make use of the remote
sensing technique for quantifying the sources and sinks of CO2 not only
requires highly accurate satellite instruments, but also puts stringent
requirements on the performance of atmospheric transport models.
Improving the accuracy of these models should receive high priority,
which calls for a closer collaboration between experts in atmospheric
dynamics and tracer transport.
BibTeX:
@article{houweling10a,
  author = {Houweling, S. and Aben, I. and Breon, F-M and Chevallier, F. and Deutscher, N. and Engelen, R. and Gerbig, C. and Griffith, D. and Hungershoefer, K. and Macatangay, R. and Marshall, J. and Notholt, J. and Peters, W. and Serrar, S.},
  title = {The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {20},
  pages = {9981--9992},
  doi = {10.5194/acp-10-9981-2010}
}
Houweling S, Krol M, Bergamaschi P, Frankenberg C, Dlugokencky EJ, Morino I, Notholt J, Sherlock V, Wunch D, Beck V, Gerbig C, Chen H, Kort EA, Rockmann T and Aben I ({2014}), "A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({8}), pp. 3991-4012.
Abstract: This study investigates the use of total column CH4 (XCH4) retrievals
from the SCIAMACHY satellite instrument for quantifying large-scale
emissions of methane. A unique data set from SCIAMACHY is available
spanning almost a decade of measurements, covering a period when the
global CH4 growth rate showed a marked transition from stable to
increasing mixing ratios. The TM5 4DVAR inverse modelling system has
been used to infer CH4 emissions from a combination of satellite and
surface measurements for the period 2003-2010. In contrast to earlier
inverse modelling studies, the SCIAMACHY retrievals have been corrected
for systematic errors using the TCCON network of ground-based Fourier
transform spectrometers. The aim is to further investigate the role of
bias correction of satellite data in inversions. Methods for bias
correction are discussed, and the sensitivity of the optimized emissions
to alternative bias correction functions is quantified. It is found that
the use of SCIAMACHY retrievals in TM5 4DVAR increases the estimated
inter-annual variability of large-scale fluxes by 22% compared with the
use of only surface observations. The difference in global methane
emissions between 2-year periods before and after July 2006 is estimated
at 27-35 Tg yr(-1). The use of SCIAMACHY retrievals causes a shift in
the emissions from the extra-tropics to the tropics of 50 +/- 25 Tg
yr(-1). The large uncertainty in this value arises from the uncertainty
in the bias correction functions. Using measurements from the HIPPO and
BARCA aircraft campaigns, we show that systematic errors in the
SCIAMACHY measurements are a main factor limiting the performance of the
inversions. To further constrain tropical emissions of methane using
current and future satellite missions, extended validation capabilities
in the tropics are of critical importance.
BibTeX:
@article{houweling14a,
  author = {Houweling, S. and Krol, M. and Bergamaschi, P. and Frankenberg, C. and Dlugokencky, E. J. and Morino, I. and Notholt, J. and Sherlock, V. and Wunch, D. and Beck, V. and Gerbig, C. and Chen, H. and Kort, E. A. and Rockmann, T. and Aben, I.},
  title = {A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {8},
  pages = {3991--4012},
  doi = {10.5194/acp-14-3991-2014}
}
Houweling S, Bergamaschi P, Chevallier F, Heimann M, Kaminski T, Krol M, Michalak AM and Patra P ({2017}), "Global inverse modeling of CH4 sources and sinks: an overview of methods", ATMOSPHERIC CHEMISTRY AND PHYSICS., JAN 4, {2017}. Vol. {17}({1}), pp. 235-256.
Abstract: The aim of this paper is to present an overview of inverse modeling
methods that have been developed over the years for estimating the
global sources and sinks of CH4. It provides insight into how techniques
and estimates have evolved over time and what the remaining shortcomings
are. As such, it serves a didactical purpose of introducing apprentices
to the field, but it also takes stock of developments so far and
reflects on promising new directions. The main focus is on
methodological aspects that are particularly relevant for CH4, such as
its atmospheric oxidation, the use of methane isotopologues, and
specific challenges in atmospheric transport modeling of CH4. The use of
satellite retrievals receives special attention as it is an active field
of methodological development, with special requirements on the sampling
of the model and the treatment of data uncertainty. Regional scale flux
estimation and attribution is still a grand challenge, which calls for
new methods capable of combining information from multiple data streams
of different measured parameters. A process model representation of
sources and sinks in atmospheric transport inversion schemes allows the
integrated use of such data. These new developments are needed not only
to improve our understanding of the main processes driving the observed
global trend but also to support international efforts to reduce
greenhouse gas emissions.
BibTeX:
@article{houweling17a,
  author = {Houweling, Sander and Bergamaschi, Peter and Chevallier, Frederic and Heimann, Martin and Kaminski, Thomas and Krol, Maarten and Michalak, Anna M. and Patra, Prabir},
  title = {Global inverse modeling of CH4 sources and sinks: an overview of methods},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {1},
  pages = {235--256},
  doi = {10.5194/acp-17-235-2017}
}
Hsueh D (2009), "New York City's Metropolitan Dome: past and present CO2 concentration patterns from an urban to rural gradient". Thesis at: Columbia University, New York.
BibTeX:
@mastersthesis{hsueh09a,
  author = {Hsueh, Diana},
  title = {New York City's Metropolitan Dome: past and present CO2 concentration patterns from an urban to rural gradient},
  school = {Columbia University, New York},
  year = {2009}
}
Hu L, Montzka SA, Miller JB, Andrews AE, Lehman SJ, Miller BR, Thoning K, Sweeney C, Chen H, Godwin DS, Masarie K, Bruhwiler L, Fischer ML, Biraud SC, Torn MS, Mountain M, Nehrkorn T, Eluszkiewicz J, Miller S, Draxler RR, Stein AF, Hall BD, Elkins JW and Tans PP ({2015}), "US emissions of HFC-134a derived for 2008-2012 from an extensive flask-air sampling network", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2015}. Vol. {120}({2}), pp. 801-825.
Abstract: U.S. national and regional emissions of HFC-134a are derived for
2008-2012 based on atmospheric observations from ground and aircraft
sites across the U.S. and a newly developed regional inverse model.
Synthetic data experiments were first conducted to optimize the model
assimilation design and to assess model-data mismatch errors and prior
flux error covariances computed using a maximum likelihood estimation
technique. The synthetic data experiments also tested the sensitivity of
derived national and regional emissions to a range of assumed prior
emissions, with the goal of designing a system that was minimally
reliant on the prior. We then explored the influence of additional
sources of error in inversions with actual observations, such as those
associated with background mole fractions and transport uncertainties.
Estimated emissions of HFC-134a range from 52 to 61 Gg yr(-1) for the
contiguous U.S. during 2008-2012 for inversions using air transport from
Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model
driven by the 12km resolution meteorogical data from North American
Mesoscale Forecast System (NAM12) and all tested combinations of prior
emissions and background mole fractions. Estimated emissions for
2008-2010 were 20% lower when specifying alternative transport from
Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by
the Weather Research and Forecasting (WRF) meteorology. Our estimates
(for HYSPLIT-NAM12) are consistent with annual emissions reported by
U.S. Environmental Protection Agency for the full study interval. The
results suggest a 10-20% drop in U.S. national HFC-134a emission in
2009 coincident with a reduction in transportation-related fossil fuel
CO2 emissions, perhaps related to the economic recession. All inversions
show seasonal variation in national HFC-134a emissions in all years,
with summer emissions greater than winter emissions by 20-50%.
BibTeX:
@article{hu15a,
  author = {Hu, Lei and Montzka, Stephen A. and Miller, John B. and Andrews, Aryln E. and Lehman, Scott J. and Miller, Benjamin R. and Thoning, Kirk and Sweeney, Colm and Chen, Huilin and Godwin, David S. and Masarie, Kenneth and Bruhwiler, Lori and Fischer, Marc L. and Biraud, Sebastien C. and Torn, Margaret S. and Mountain, Marikate and Nehrkorn, Thomas and Eluszkiewicz, Janusz and Miller, Scot and Draxler, Roland R. and Stein, Ariel F. and Hall, Bradley D. and Elkins, James W. and Tans, Pieter P.},
  title = {US emissions of HFC-134a derived for 2008-2012 from an extensive flask-air sampling network},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2015},
  volume = {120},
  number = {2},
  pages = {801--825},
  doi = {10.1002/2014JD022617}
}
Hu C, Griffis TJ, Lee X, Millet DB, Chen Z, Baker JM and Xiao K ({2018}), "Top-Down Constraints on Anthropogenic CO2 Emissions Within an Agricultural-Urban Landscape", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 16, {2018}. Vol. {123}({9}), pp. {4674-4694}.
Abstract: Anthropogenic carbon dioxide (CO2) emissions dominate the atmospheric
greenhouse gas radiative forcing budget. However, these emissions are
poorly constrained at the regional (10(2)-10(6)km(2)) and seasonal
scales. Here we use a combination of tall tower CO2 mixing ratio and
carbon isotope ratio observations and inverse modeling techniques to
constrain anthropogenic CO2 emissions within a highly heterogeneous
agricultural landscape near Saint Paul, Minnesota, in the Upper
Midwestern United States. The analyses indicate that anthropogenic
emissions contributed 6.6, 6.8, and 7.4mol/mol annual CO2 enhancements
(i.e., departures from the background values) in 2008, 2009, and 2010,
respectively. Oil refinery, the energy industry (power and heat
generation), and residential emissions (home heating and cooking)
contributed 2.9 (42.5, 1.4 (19.8, and 1.1mol/mol (15.8 of the
total anthropogenic enhancement over the 3-year period according to a
priori inventories. The total anthropogenic signal was further
partitioned into CO2 emissions derived from fuel oil, natural gas, coal,
gasoline, and diesel consumption using inverse modeling and carbon
isotope ratio analyses. The results indicate that fuel oil and natural
gas consumption accounted for 52.5% of the anthropogenic CO2 sources in
winter. Here the a posteriori CO2 emission from natural gas was
79.04.1% (a priori 20.0 and accounted for 63% of the total CO2
enhancement including both biological and anthropogenic sources. The a
posteriori CO2 emission from fuel oil was 8.43.8% (a priori
32.5suggesting a more important role of residential heating in
winter. The modeled carbon isotope ratio of the CO2 source (delta
C-13(s), -29.3 +/- 0.4 was relatively more enriched in C-13-CO2
compared to that derived from Miller-Tans plot analyses (-35.5 parts per
thousand to -34.8 parts per thousand), supporting that natural gas
consumption was underestimated for this region.
BibTeX:
@article{hu18a,
  author = {Hu, Cheng and Griffis, Timothy J. and Lee, Xuhui and Millet, Dylan B. and Chen, Zichong and Baker, John M. and Xiao, Ke},
  title = {Top-Down Constraints on Anthropogenic CO2 Emissions Within an Agricultural-Urban Landscape},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2018},
  volume = {123},
  number = {9},
  pages = {4674-4694},
  doi = {{10.1029/2017JD027881}}
}
Hu H, Landgraf J, Detmers R, Borsdorff T, de Brugh JA, Aben I, Butz A and Hasekamp O ({2018}), "Toward Global Mapping of Methane With TROPOMI: First Results and Intersatellite Comparison to GOSAT", GEOPHYSICAL RESEARCH LETTERS., APR 28, {2018}. Vol. {45}({8}), pp. {3682-3689}.
Abstract: The TROPOspheric Monitoring Instrument (TROPOMI), launched on 13 October
2017, aboard the Sentinel-5 Precursor satellite, measures reflected
sunlight in the ultraviolet, visible, near-infrared, and shortwave
infrared spectral range. It enables daily global mapping of key
atmospheric species for monitoring air quality and climate. We present
the first methane observations from November and December 2017, using
TROPOMI radiance measurements in the shortwave infrared band around 2.3
mu m. We compare our results with the methane product obtained from the
Greenhouse gases Observing SAT-ellite (GOSAT). Although different
spectral ranges and retrieval methods are used, we find excellent
agreement between the methane products acquired from the two satellites
with a mean difference of 13.6 ppb, standard deviation of 19.6 ppb, and
Pearson's correlation coefficient of 0.95. Our preliminary results
capture the latitudinal gradient and show expected regional
enhancements, for example, in the African Sudd wetlands, with much more
detail than has been observed before.
Plain Language Summary Methane is the second most important
anthropogenic greenhouse gas. Improved knowledge about methane
variations and detection of localized sources is of great importance for
scientists, policy makers, and private companies. One of the goals of
the recently launched European Space Agency Sentinel-5 Precursor
satellite, with on board the cutting-edge TROPOspheric Monitoring
Instrument (TROPOMI), is to measure methane with an unprecedented
combination of accuracy, spatial coverage, and resolution. This work
presents the first TROPOMI methane measurements and shows that these are
in excellent agreement with methane measurements from the validated
Japanese Greenhouse gases Observing SATellite satellite.
BibTeX:
@article{hu18b,
  author = {Hu, Haili and Landgraf, Jochen and Detmers, Rob and Borsdorff, Tobias and de Brugh, Joost Aan and Aben, Ilse and Butz, Andre and Hasekamp, Otto},
  title = {Toward Global Mapping of Methane With TROPOMI: First Results and Intersatellite Comparison to GOSAT},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2018},
  volume = {45},
  number = {8},
  pages = {3682-3689},
  doi = {{10.1002/2018GL077259}}
}
Hu C, Liu S, Wang Y, Zhang M, Xiao W, Wang W and Xu J ({2018}), "Anthropogenic CO2 emissions from a megacity in the Yangtze River Delta of China", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., AUG, {2018}. Vol. {25}({23, SI}), pp. {23157-23169}.
Abstract: Anthropogenic CO2 emissions from cities represent a major source
contributing to the global atmospheric CO2 burden. Here, we examined the
enhancement of atmospheric CO2 mixing ratios by anthropogenic emissions
within the Yangtze River Delta (YRD), China, one of the world's most
densely populated regions (population greater than 150 million). Tower
measurements of CO2 mixing ratios were conducted from March 2013 to
August 2015 and were combined with numerical source footprint modeling
to help constrain the anthropogenic CO2 emissions. We simulated the CO2
enhancements (i.e., fluctuations superimposed on background values) for
winter season (December, January, and February). Overall, we observed
mean diurnal variation of CO2 enhancement of 23.5 similar to 49.7 mu mol
mol(-1), 21.4 similar to 52.4 mu mol mol(-1), 28.1 similar to 55.4 mu
mol mol(-1), and 29.5 similar to 42.4 mu mol mol(-1) in spring, summer,
autumn, and winter, respectively. These enhancements were much larger
than previously reported values for other countries. The diurnal CO2
enhancements reported here showed strong similarity for all 3 years of
the study. Results from source footprint modeling indicated that our
tower observations adequately represent emissions from the broader YRD
area. Here, the east of Anhui and the west of Jiangsu province
contributed significantly more to the anthropogenic CO2 enhancement
compared to the other sectors of YRD. The average anthropogenic CO2
emission in 2014 was 0.162 (+/- 0.005) mg m(-2) s(-1) and was 7 +/- 3br> higher than 2010 for the YRD. Overall, our emission estimates were
significantly smaller (9.5 than those estimated (0.179 mg m(-2)
s(-1)) from the EDGAR emission database.
BibTeX:
@article{hu18c,
  author = {Hu, Cheng and Liu, Shoudong and Wang, Yongwei and Zhang, Mi and Xiao, Wei and Wang, Wei and Xu, Jiaping},
  title = {Anthropogenic CO2 emissions from a megacity in the Yangtze River Delta of China},
  journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
  year = {2018},
  volume = {25},
  number = {23, SI},
  pages = {23157-23169},
  doi = {{10.1007/s11356-018-2325-3}}
}
Humpage N, Boesch H, Palmer PI, Vick A, Parr-Burman P, Wells M, Pearson D, Strachan J and Bezawada N ({2018}), "GreenHouse gas Observations of the Stratosphere and Troposphere (GHOST): an airborne shortwave-infrared spectrometer for remote sensing of greenhouse gases", ATMOSPHERIC MEASUREMENT TECHNIQUES., SEP 12, {2018}. Vol. {11}({9}), pp. {5199-5222}.
Abstract: GHOST is a novel, compact shortwave-infrared grating spectrometer,
designed for remote sensing of tropospheric columns of greenhouse gases
(GHGs) from an airborne platform. It observes solar radiation at medium
to high spectral resolution (better than 0.3 nm), which has been
reflected by the Earth's surface using similar methods to those used by
polar-orbiting satellites such as the JAXA GOSAT mission, NASA's OCO-2,
and the Copernicus Sentinel-5 Precursor. By using an original design
comprising optical fibre inputs along with a single diffraction grating
and detector array, GHOST is able to observe CO2 absorption bands
centred around 1.61 and 2.06 mu m (the same wavelength regions used by
OCO-2 and GOSAT) whilst simultaneously measuring CH4 absorption at 1.65
mu m (also observed by GOSAT) and CH4 and CO at 2.30 mu m (observed by
Sentinel-5P). With emissions expected to become more concentrated
towards city sources as the global population residing in urban areas
increases, there emerges a clear requirement to bridge the spatial scale
gap between small-scale urban emission sources and global-scale GHG
variations. In addition to the benefits achieved in spatial coverage
through being able to remotely sense GHG tropospheric columns from an
aircraft, the overlapping spectral ranges and comparable spectral
resolutions mean that GHOST has unique potential for providing
validation opportunities for these platforms, particularly over the
ocean, where ground-based validation measurements are not available. In
this paper we provide an overview of the GHOST instrument, calibration,
and data processing, demonstrating the instrument's performance and
suitability for GHG remote sensing. We also report on the first GHG
observations made by GHOST during its maiden science flights on board
the NASA Global Hawk unmanned aerial vehicle, which took place over the
eastern Pacific Ocean in March 2015 as part of the CAST/ATTREX joint
Global Hawk flight campaign.
BibTeX:
@article{humpage18a,
  author = {Humpage, Neil and Boesch, Hartmut and Palmer, Paul I. and Vick, Andy and Parr-Burman, Phil and Wells, Martyn and Pearson, David and Strachan, Jonathan and Bezawada, Naidu},
  title = {GreenHouse gas Observations of the Stratosphere and Troposphere (GHOST): an airborne shortwave-infrared spectrometer for remote sensing of greenhouse gases},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2018},
  volume = {11},
  number = {9},
  pages = {5199-5222},
  doi = {{10.5194/amt-11-5199-2018}}
}
Hungershoefer K, Breon FM, Peylin P, Chevallier F, Rayner P, Klonecki A, Houweling S and Marshall J ({2010}), "Evaluation of various observing systems for the global monitoring of CO2 surface fluxes", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({21}), pp. 10503-10520.
Abstract: In the context of rising greenhouse gas concentrations, and the
potential feedbacks between climate and the carbon cycle, there is an
urgent need to monitor the exchanges of carbon between the atmosphere
and both the ocean and the land surfaces. In the so-called top-down
approach, the surface fluxes of CO2 are inverted from the observed
spatial and temporal concentration gradients. The concentrations of CO2
are measured in-situ at a number of surface stations unevenly
distributed over the Earth while several satellite missions may be used
to provide a dense and better-distributed set of observations to
complement this network. In this paper, we compare the ability of
different CO2 concentration observing systems to constrain surface
fluxes. The various systems are based on realistic scenarios of sampling
and precision for satellite and in-situ measurements.
It is shown that satellite measurements based on the differential
absorption technique (such as those of SCIAMACHY, GOSAT or OCO) provide
more information than the thermal infrared observations (such as those
of AIRS or IASI). The OCO observations will provide significantly better
information than those of GOSAT. A CO2 monitoring mission based on an
active (lidar) technique could potentially provide an even better
constraint. This constraint can also be realized with the very dense
surface network that could be built with the same funding as that of the
active satellite mission. Despite the large uncertainty reductions on
the surface fluxes that may be expected from these various observing
systems, these reductions are still insufficient to reach the highly
demanding requirements for the monitoring of anthropogenic emissions of
CO2 or the oceanic fluxes at a spatial scale smaller than that of
oceanic basins. The scientific objective of these observing system
should therefore focus on the fluxes linked to vegetation and land
ecosystem dynamics.
BibTeX:
@article{hungershoefer10a,
  author = {Hungershoefer, K. and Breon, F. -M. and Peylin, P. and Chevallier, F. and Rayner, P. and Klonecki, A. and Houweling, S. and Marshall, J.},
  title = {Evaluation of various observing systems for the global monitoring of CO2 surface fluxes},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {21},
  pages = {10503--10520},
  doi = {10.5194/acp-10-10503-2010}
}
Huntzinger DN, Gourdji SM, Mueller KL and Michalak AM ({2011}), "The utility of continuous atmospheric measurements for identifying biospheric CO2 flux variability", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 23, {2011}. Vol. {116}
Abstract: Motivated by the need to improve the modeling of land-atmosphere carbon
exchange, this study examines the extent to which continuous atmospheric
carbon dioxide (CO2) observations can be used to evaluate flux
variability at regional scales. The net ecosystem exchange estimates of
four terrestrial biospheric models (TBMs) are used to represent
plausible scenarios of surface flux distributions, which are compared in
terms of their resulting atmospheric signals. The analysis focuses on
North America using the nine towers of the continuous observation
network that were operational in 2004. Four test cases are designed to
isolate the influence on the atmospheric observations of (1) overall
flux differences, (2) magnitude differences in flux across large
regions, (3) differences in the flux patterns within ecoregions, and (4)
flux variability in the near and far field of observation locations. The
CO2 signals generated from the different representations of surface flux
distribution are compared using a Chi-square test of variance.
Differences found to be significant are driven primarily by differences
in flux magnitude over large scales, and the fine-scale (primarily
temporal) variability of fluxes within the near field of observation
locations. Differences in the spatial distribution of fluxes within
individual ecoregions, on the other hand, do not translate into
significant differences in the observed signals at the towers. Thus,
given the types of variation in flux represented by the four TBMs, the
atmospheric data may be most informative in the evaluation of aggregated
fluxes over large spatial scales (e. g., ecoregions), as well as in the
improvement of how the diurnal cycle of fluxes is represented in TBMs,
particularly in areas close to tower locations.
BibTeX:
@article{huntzinger11a,
  author = {Huntzinger, Deborah N. and Gourdji, Sharon M. and Mueller, Kimberly L. and Michalak, Anna M.},
  title = {The utility of continuous atmospheric measurements for identifying biospheric CO2 flux variability},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JD015048}
}
Huntzinger DN, Gourdji SM, Mueller KL and Michalak AM ({2011}), "A systematic approach for comparing modeled biospheric carbon fluxes across regional scales", BIOGEOSCIENCES. Vol. {8}({6}), pp. 1579-1593.
Abstract: Given the large differences between biospheric model estimates of
regional carbon exchange, there is a need to understand and reconcile
the predicted spatial variability of fluxes across models. This paper
presents a set of quantitative tools that can be applied to
systematically compare flux estimates despite the inherent differences
in model formulation. The presented methods include variogram analysis,
variable selection, and geostatistical regression. These methods are
evaluated in terms of their ability to assess and identify differences
in spatial variability in flux estimates across North America among a
small subset of models, as well as differences in the environmental
drivers that best explain the spatial variability of predicted fluxes.
The examined models are the Simple Biosphere (SiB 3.0), Carnegie Ames
Stanford Approach (CASA), and CASA coupled with the Global Fire
Emissions Database (CASA GFEDv2), and the analyses are performed on
model-predicted net ecosystem exchange, gross primary production, and
ecosystem respiration. Variogram analysis reveals consistent seasonal
differences in spatial variability among modeled fluxes at a 1 degrees x
1 degrees spatial resolution. However, significant differences are
observed in the overall magnitude of the carbon flux spatial variability
across models, in both net ecosystem exchange and component fluxes.
Results of the variable selection and geostatistical regression analyses
suggest fundamental differences between the models in terms of the
factors that explain the spatial variability of predicted flux. For
example, carbon flux is more strongly correlated with percent land cover
in CASA GFEDv2 than in SiB or CASA. Some of the differences in spatial
patterns of estimated flux can be linked back to differences in model
formulation, and would have been difficult to identify simply by
comparing net fluxes between models. Overall, the systematic approach
presented here provides a set of tools for comparing predicted
grid-scale fluxes across models, a task that has historically been
difficult unless standardized forcing data were prescribed, or a
detailed sensitivity analysis performed.
BibTeX:
@article{huntzinger11b,
  author = {Huntzinger, D. N. and Gourdji, S. M. and Mueller, K. L. and Michalak, A. M.},
  title = {A systematic approach for comparing modeled biospheric carbon fluxes across regional scales},
  journal = {BIOGEOSCIENCES},
  year = {2011},
  volume = {8},
  number = {6},
  pages = {1579--1593},
  doi = {10.5194/bg-8-1579-2011}
}
Hutjes RWA, Vellinga US, Gioli B and Miglietta F ({2010}), "Dis-aggregation of airborne flux measurements using footprint analysis", AGRICULTURAL AND FOREST METEOROLOGY., JUL 15, {2010}. Vol. {150}({7-8}), pp. 966-983.
Abstract: Aircraft measurements of turbulent fluxes are generally being made with
the objective to obtain an estimate of regional exchanges between land
surface and atmosphere, to investigate the spatial variability of these
fluxes, but also to learn something about the fluxes from some or all of
the land cover types that make up the landscape. In this study we
develop a method addressing this last objective, an approach to
disentangle blended fluxes from a landscape into the component fluxes
emanating from the various land cover classes making up that landscape.
The method relies on using a footprint model to determine which part of
the landscape the airborne flux observation refers to, using a high
resolution land cover map to determine the fractional covers of the
various land cover classes within that footprint, and finally using
multiple linear regression on many such flux/fractional cover data
records to estimate the component fluxes. The method is developed in the
context of three case studies of increasing complexity and the analysis
covers three scalar fluxes: sensible and latent heat fluxes and carbon
dioxide flux, as well as the momentum flux.
A basic assumption under the dis-aggregation method is that the
composite flux, i.e. the landscape flux, is a linear average of the
component fluxes, i.e. the fluxes from the various land elements. We
test and justify this assumption by comparing linear averages of
component fluxes in simple `binary landscapes', weighted by their
relative area, with directly aircraft observed fluxes.
In all case studies dis-aggregation of mixed values for fluxes from
heterogeneous areas into component land cover class specific fluxes is
feasible using robust least squares regression, both in simple binary
`landscapes' and in more complex cases. Both the differences between
land cover classes and the differences between synoptic conditions can
be resolved, for those land cover classes that make up sufficiently
large fractions of the landscape. The regression F-statistic and the
closely associated p-values are good indicators for this latter
prerequisite and for other sources of uncertainty in the dis-aggregated
flux estimates that render it meaningful or not. An analysis of the
effect of various sources of errors in input data, footprint estimates
and of skewed land cover class distributions is presented. A validation
of flux estimates obtained through the dis-aggregation method against
independent ground data proved satisfactorily. Recommendations for the
use of the method are given as are suggestions for further development.
(C) 2010 Elsevier B.V. All rights reserved.
BibTeX:
@article{hutjes10a,
  author = {Hutjes, R. W. A. and Vellinga, U. S. and Gioli, B. and Miglietta, F.},
  title = {Dis-aggregation of airborne flux measurements using footprint analysis},
  journal = {AGRICULTURAL AND FOREST METEOROLOGY},
  year = {2010},
  volume = {150},
  number = {7-8},
  pages = {966--983},
  doi = {10.1016/j.agrformet.2010.03.004}
}
Hutjes R, Bosveld F, Dolman A, Houweling S, Peters W, Meesters A, Moene A, Neubert R, KleinBaltink H, Unal C and others (2012), "Titel rapport AN ASSESSMENT OF THE POTENTIAL FOR ATMOSPHERIC EMISSION VERIFICATION IN THE NETHERLANDS". Thesis at: Wageningen University and Research Centre.
BibTeX:
@techreport{hutjes12a,
  author = {Hutjes, RWA and Bosveld, FC and Dolman, AJ and Houweling, S and Peters, W and Meesters, AGCA and Moene, A and Neubert, REM and KleinBaltink, H and Unal, CMH and others},
  title = {Titel rapport AN ASSESSMENT OF THE POTENTIAL FOR ATMOSPHERIC EMISSION VERIFICATION IN THE NETHERLANDS},
  school = {Wageningen University and Research Centre},
  year = {2012},
  url = {https://www.researchgate.net/profile/Ronald_Hutjes/publication/283419017_An_assessment_of_the_potential_for_atmospheric_emission_verification_in_The_Netherlands/links/5640741a08ae34e98c4e8221/An-assessment-of-the-potential-for-atmospheric-emission-verification-in-The-Netherlands.pdf}
}
Isaac LID, Lauvaux T, Davis KJ, Miles NL, Richardson SJ, Jacobson AR and Andrews AE ({2014}), "Model-data comparison of MCI field campaign atmospheric CO2 mole fractions", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 16, {2014}. Vol. {119}({17})
Abstract: Atmospheric transport model errors are a major contributor to
uncertainty in CO2 inverse flux estimates. Our study compares CO2 mole
fraction observations from the North American Carbon Program
Mid-Continental Intensive (MCI) field campaign and modeled mole
fractions from two atmospheric transport models: the global Transport
Model 5 from NOAA's CarbonTracker system and the mesoscale Weather
Research and Forecasting model. Both models are coupled to identical CO2
fluxes and lateral boundary conditions from CarbonTracker (CT2009
release). Statistical analyses were performed for two periods of 2007
using observed daily daytime average mole fractions of CO2 to test the
ability of these models to reproduce the observations and to infer
possible causes of the discrepancies. TM5-CT2009 overestimates midsummer
planetary boundary layer CO2 for sites in the U. S. corn belt by 10 ppm.
Weather Research and Forecasting (WRF)-CT2009 estimates diverge from the
observations with similar magnitudes, but the signs of the differences
vary from site to site. The modeled mole fractions are highly correlated
with the observed seasonal cycle (r >= 0.7) but less correlated in the
growing season, where weather-related changes in CO2 dominate the
observed variability. Spatial correlations in residuals from TM5-CT2009
are higher than WRF-CT2009 perhaps due to TM5's coarse horizontal
resolution and shallow vertical mixing. Vertical mixing appears to have
influenced CO2 residuals from both models. TM5-CT2009 has relatively
weak vertical mixing near the surface limiting the connection between
local CO2 surface fluxes and boundary layer. WRF-CT2009 has stronger
vertical mixing that may increase the connections between local surface
fluxes and the boundary layer.
BibTeX:
@article{isaac14a,
  author = {Isaac, Liza I. Diaz and Lauvaux, Thomas and Davis, Kenneth J. and Miles, Natasha L. and Richardson, Scott J. and Jacobson, Andrew R. and Andrews, Arlyn E.},
  title = {Model-data comparison of MCI field campaign atmospheric CO2 mole fractions},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2014},
  volume = {119},
  number = {17},
  doi = {10.1002/2014JD021593}
}
Ishidoya S, Aoki S, Goto D, Nakazawa T, Taguchi S and Patra PK ({2012}), "Time and space variations of the O-2/N-2 ratio in the troposphere over Japan and estimation of the global CO2 budget for the period 2000-2010", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {64}
Abstract: Systematic measurements of the atmospheric O-2/N-2 ratio have been made
using aircraft and ground-based stations in Japan since 1999. The
observed seasonal cycles of the O-2/N-2 ratio and atmospheric potential
oxygen (APO) vary almost in opposite phase to that of the CO2
concentration at all altitudes, and their amplitudes and phases are
generally reduced and delayed, respectively, with increasing altitude.
Simulations of APO using two atmospheric transport models reproduce
general features of the observed seasonal cycle, but both models fail to
reproduce the phase at an altitude ranging from 8 km to the tropopause.
By analysing the observed secular trends of APO and CO2 concentration,
and assuming a global net oceanic O-2 outgassing of 0.2 +/- 0.5 GtC
yr(-1), we estimate global average terrestrial biospheric and oceanic
CO2 uptake for the period 2000-2010 to be 1.0 +/- 0.8 and 2.5 +/- 0.7
GtC yr(-1), respectively.
BibTeX:
@article{ishidoya12a,
  author = {Ishidoya, Shigeyuki and Aoki, Shuji and Goto, Daisuke and Nakazawa, Takakiyo and Taguchi, Shoichi and Patra, Prabir K.},
  title = {Time and space variations of the O-2/N-2 ratio in the troposphere over Japan and estimation of the global CO2 budget for the period 2000-2010},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2012},
  volume = {64},
  doi = {10.3402/tellusb.v64i0.18964}
}
Ishii M, Feely RA, Rodgers KB, Park GH, Wanninkhof R, Sasano D, Sugimoto H, Cosca CE, Nakaoka S, Telszewski M, Nojiri Y, Fletcher SEM, Niwa Y, Patra PK, Valsala V, Nakano H, Lima I, Doney SC, Buitenhuis ET, Aumont O, Dunne JP, Lenton A and Takahashi T ({2014}), "Air-sea CO2 flux in the Pacific Ocean for the period 1990-2009", BIOGEOSCIENCES. Vol. {11}({3}), pp. 709-734.
Abstract: Air-sea CO2 fluxes over the Pacific Ocean are known to be characterized
by coherent large-scale structures that reflect not only ocean
subduction and upwelling patterns, but also the combined effects of
wind-driven gas exchange and biology. On the largest scales, a large net
CO2 influx into the extratropics is associated with a robust seasonal
cycle, and a large net CO2 efflux from the tropics is associated with
substantial interannual variability. In this work, we have synthesized
estimates of the net air-sea CO2 flux from a variety of products,
drawing upon a variety of approaches in three sub-basins of the Pacific
Ocean, i. e., the North Pacific extratropics (18-66 degrees N), the
tropical Pacific (18 degrees S-18 degrees N), and the South Pacific
extratropics (44.5-18 degrees S). These approaches include those based
on the measurements of CO2 partial pressure in surface seawater
(pCO(2)sw), inversions of ocean-interior CO2 data, forward ocean
biogeochemistry models embedded in the ocean general circulation models
(OBGCMs), a model with assimilation of pCO(2)sw data, and inversions of
atmospheric CO2 measurements. Long-term means, interannual variations
and mean seasonal variations of the regionally integrated fluxes were
compared in each of the sub-basins over the last two decades, spanning
the period from 1990 through 2009. A simple average of the long-term
mean fluxes obtained with surface water pCO(2) diagnostics and those
obtained with ocean-interior CO2 inversions are -0.47 +/- 0.13 Pg
Cyr(-1) in the North Pacific extratropics, +/- 0.44 +/- 0.14 Pg Cyr(-1)
in the tropical Pacific, and -0.37 +/- 0.08 Pg C yr(-1) in the South
Pacific extratropics, where positive fluxes are into the atmosphere.
This suggests that approximately half of the CO2 taken up over the North
and South Pacific extratropics is released back to the atmosphere from
the tropical Pacific. These estimates of the regional fluxes are also
supported by the estimates from OBGCMs after adding the riverine CO2
flux, i.e., -0.49 +/- 0.02 Pg Cyr(-1) in the North Pacific extratropics,
+0.41 +/- 0.05 Pg Cyr(-1) in the tropical Pacific, and -0.39 +/- 0.11 Pg
Cyr(-1) in the South Pacific extratropics. The estimates from the
atmospheric CO2 inversions show large variations amongst different
inversion systems, but their median fluxes are consistent with the
estimates from climatological pCO(2)sw data and pCO(2)sw diagnostics. In
the South Pacific extratropics, where CO2 variations in the surface and
ocean interior are severely undersampled, the difference in the air-sea
CO2 flux estimates between the diagnostic models and ocean-interior CO2
inversions is larger (0.18 Pg Cyr(-1)). The range of estimates from
forward OBGCMs is also large (-0.19 to -0.72 Pg Cyr(-1)). Regarding
interannual variability of air-sea CO2 fluxes, positive and negative
anomalies are evident in the tropical Pacific during the cold and warm
events of the El Nino-Southern Oscillation in the estimates from
pCO(2)sw diagnostic models and from OBGCMs. They are consistent in phase
with the Southern Oscillation Index, but the peak-to-peak amplitudes
tend to be higher in OBGCMs (0.40 +/- 0.09 Pg Cyr(-1)) than in the
diagnostic models (0.27 +/- 0.07 Pg Cyr(-1)).
BibTeX:
@article{ishii14a,
  author = {Ishii, M. and Feely, R. A. and Rodgers, K. B. and Park, G. -H. and Wanninkhof, R. and Sasano, D. and Sugimoto, H. and Cosca, C. E. and Nakaoka, S. and Telszewski, M. and Nojiri, Y. and Fletcher, S. E. Mikaloff and Niwa, Y. and Patra, P. K. and Valsala, V. and Nakano, H. and Lima, I. and Doney, S. C. and Buitenhuis, E. T. and Aumont, O. and Dunne, J. P. and Lenton, A. and Takahashi, T.},
  title = {Air-sea CO2 flux in the Pacific Ocean for the period 1990-2009},
  journal = {BIOGEOSCIENCES},
  year = {2014},
  volume = {11},
  number = {3},
  pages = {709--734},
  doi = {10.5194/bg-11-709-2014}
}
Ito A ({2011}), "Decadal Variability in the Terrestrial Carbon Budget Caused by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation", JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN., OCT, {2011}. Vol. {89}({5}), pp. 441-454.
Abstract: The terrestrial carbon dioxide (CO2) budget interacts with the Earth's
climate system on diurnal to centennial and longer time scales, making
it critical for climatic prediction and stabilization. Atmospheric
observations and global syntheses of CO2 data indicate that the
terrestrial biosphere is one the major sources of interannual
variability, but the underlying mechanisms operating on different
time-scales and the potential impacts of this on future projections
remain unclear. Here it is shown that the El Nino and Southern
Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic
Multidecadal Oscillation (AMO) regime affect temporal variability in the
terrestrial carbon budget with different time scales. The terrestrial
carbon budget, estimated using a process-based model (VISIT) for the
period 1910-2005, was correlated with the indices of PDO, AMO, and ENSO
with various smoothing periods and lag lengths. ENSO showed the highest
short-term correlation, corresponding to interannual terrestrial
variability, whereas PDO and AMO had higher correlations at the decadal
time scale. Such correlations with the meteorological regimes occurred
heterogeneously over the land surface. Tin; study suggests that
long-term monitoring is needed to elucidate the temporal variability,
and that decadal predictability of climate and terrestrial models should
be improved further.
BibTeX:
@article{ito11a,
  author = {Ito, Akihiko},
  title = {Decadal Variability in the Terrestrial Carbon Budget Caused by the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation},
  journal = {JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN},
  year = {2011},
  volume = {89},
  number = {5},
  pages = {441--454},
  doi = {10.2151/jmsj.2011-503}
}
Jacob DJ, Turner AJ, Maasakkers JD, Sheng J, Sun K, Liu X, Chance K, Aben I, McKeever J and Frankenberg C ({2016}), "Satellite observations of atmospheric methane and their value for quantifying methane emissions", ATMOSPHERIC CHEMISTRY AND PHYSICS., NOV 18, {2016}. Vol. {16}({22}), pp. 14371-14396.
Abstract: Methane is a greenhouse gas emitted by a range of natural and
anthropogenic sources. Atmospheric methane has been measured
continuously from space since 2003, and new instruments are planned for
launch in the near future that will greatly expand the capabilities of
space-based observations. We review the value of current, future, and
proposed satellite observations to better quantify and understand
methane emissions through inverse analyses, from the global scale down
to the scale of point sources and in combination with suborbital
(surface and aircraft) data. Current global observations from Greenhouse
Gases Observing Satellite (GOSAT) are of high quality but have sparse
spatial coverage. They can quantify methane emissions on a regional
scale (100-1000 km) through multiyear averaging. The Tropospheric
Monitoring Instrument (TROPOMI), to be launched in 2017, is expected to
quantify daily emissions on the regional scale and will also effectively
detect large point sources. A different observing strategy by GHGSat
(launched in June 2016) is to target limited viewing domains with very
fine pixel resolution in order to detect a wide range of methane point
sources. Geostationary observation of methane, still in the proposal
stage, will have the unique capability of mapping source regions with
high resolution, detecting transient ``super-emitter'' point sources
and resolving diurnal variation of emissions from sources such as
wetlands and manure. Exploiting these rapidly expanding satellite
measurement capabilities to quantify methane emissions requires a
parallel effort to construct high-quality spatially and sectorally
resolved emission inventories. Partnership between top-down inverse
analyses of atmospheric data and bottom-up construction of emission
inventories is crucial to better understanding methane emission
processes and subsequently informing climate policy.
BibTeX:
@article{jacob16a,
  author = {Jacob, Daniel J. and Turner, Alexander J. and Maasakkers, Joannes D. and Sheng, Jianxiong and Sun, Kang and Liu, Xiong and Chance, Kelly and Aben, Ilse and McKeever, Jason and Frankenberg, Christian},
  title = {Satellite observations of atmospheric methane and their value for quantifying methane emissions},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {22},
  pages = {14371--14396},
  doi = {10.5194/acp-16-14371-2016}
}
Jamroensan A (2013), "Improving bottom-up and top-down estimates of carbon fluxes in the Midwestern USA". Thesis at: The University of Iowa.
BibTeX:
@phdthesis{jamroensan13a,
  author = {Jamroensan, Aditsuda},
  title = {Improving bottom-up and top-down estimates of carbon fluxes in the Midwestern USA},
  school = {The University of Iowa},
  year = {2013},
  url = {http://search.proquest.com/openview/0101c608a315817af6e44eee3c2c3053/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Jiang F, Wang HW, Chen JM, Zhou LX, Ju WM, Ding AJ, Liu LX and Peters W ({2013}), "Nested atmospheric inversion for the terrestrial carbon sources and sinks in China", BIOGEOSCIENCES. Vol. {10}({8}), pp. 5311-5324.
Abstract: In this study, we establish a nested atmospheric inversion system with a
focus on China using the Bayesian method. The global surface is
separated into 43 regions based on the 22 TransCom large regions, with
13 small regions in China. Monthly CO2 concentrations from 130
GlobalView sites and 3 additional China sites are used in this system.
The core component of this system is an atmospheric transport matrix,
which is created using the TM5 model with a horizontal resolution of 3
degrees x 2 degrees. The net carbon fluxes over the 43 global land and
ocean regions are inverted for the period from 2002 to 2008. The
inverted global terrestrial carbon sinks mainly occur in boreal Asia,
South and Southeast Asia, eastern America and southern South America.
Most China areas appear to be carbon sinks, with strongest carbon sinks
located in Northeast China. From 2002 to 2008, the global terrestrial
carbon sink has an increasing trend, with the lowest carbon sink in
2002. The inter-annual variation (IAV) of the land sinks shows
remarkable correlation with the El Nino Southern Oscillation (ENSO). The
terrestrial carbon sinks in China also show an increasing trend.
However, the IAV in China is not the same as that of the globe. There is
relatively stronger land sink in 2002, lowest sink in 2006, and
strongest sink in 2007 in China. This IAV could be reasonably explained
with the IAVs of temperature and precipitation in China. The mean global
and China terrestrial carbon sinks over the period 2002-2008 are -3.20
+/- 0.63 and -0.28 +/- 0.18 PgC yr(-1), respectively. Considering the
carbon emissions in the form of reactive biogenic volatile organic
compounds (BVOCs) and from the import of wood and food, we further
estimate that China's land sink is about -0.31 PgC yr(-1).
BibTeX:
@article{jiang13a,
  author = {Jiang, F. and Wang, H. W. and Chen, J. M. and Zhou, L. X. and Ju, W. M. and Ding, A. J. and Liu, L. X. and Peters, W.},
  title = {Nested atmospheric inversion for the terrestrial carbon sources and sinks in China},
  journal = {BIOGEOSCIENCES},
  year = {2013},
  volume = {10},
  number = {8},
  pages = {5311--5324},
  doi = {10.5194/bg-10-5311-2013}
}
Jiang F, Chen JM, Zhou L, Ju W, Zhang H, Machida T, Ciais P, Peters W, Wang H, Chen B, Liu L, Zhang C, Matsueda H and Sawa Y ({2016}), "A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches", SCIENTIFIC REPORTS., FEB 29, {2016}. Vol. {6}
Abstract: Atmospheric inversions use measurements of atmospheric CO2 gradients to
constrain regional surface fluxes. Current inversions indicate a net
terrestrial CO2 sink in China between 0.16 and 0.35 PgC/yr. The
uncertainty of these estimates is as large as the mean because the
atmospheric network historically contained only one high altitude
station in China. Here, we revisit the calculation of the terrestrial
CO2 flux in China, excluding emissions from fossil fuel burning and
cement production, by using two inversions with three new CO2 monitoring
stations in China as well as aircraft observations over Asia. We
estimate a net terrestrial CO2 uptake of 0.39-0.51 PgC/yr with a mean of
0.45 PgC/yr in 2006-2009. After considering the lateral transport of
carbon in air and water and international trade, the annual mean carbon
sink is adjusted to 0.35 PgC/yr. To evaluate this top-down estimate, we
constructed an independent bottom-up estimate based on ecosystem data,
and giving a net land sink of 0.33 PgC/yr. This demonstrates closure
between the top-down and bottom-up estimates. Both top-down and
bottom-up estimates give a higher carbon sink than previous estimates
made for the 1980s and 1990s, suggesting a trend towards increased
uptake by land ecosystems in China.
BibTeX:
@article{jiang16a,
  author = {Jiang, Fei and Chen, Jing M. and Zhou, Lingxi and Ju, Weimin and Zhang, Huifang and Machida, Toshinobu and Ciais, Philippe and Peters, Wouter and Wang, Hengmao and Chen, Baozhang and Liu, Lixin and Zhang, Chunhua and Matsueda, Hidekazu and Sawa, Yousuke},
  title = {A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches},
  journal = {SCIENTIFIC REPORTS},
  year = {2016},
  volume = {6},
  doi = {10.1038/srep22130}
}
Jiang X, Crisp D, Olsen ET, Kulawik SS, Miller CE, Pagano TS, Liang M and Yung YL (2016), "CO2 annual and semiannual cycles from multiple satellite retrievals and models", Earth and Space Science. Vol. 3(2), pp. 78-87.
BibTeX:
@article{jiang16b,
  author = {Jiang, Xun and Crisp, David and Olsen, Edward T and Kulawik, Susan S and Miller, Charles E and Pagano, Thomas S and Liang, Maochang and Yung, Yuk L},
  title = {CO2 annual and semiannual cycles from multiple satellite retrievals and models},
  journal = {Earth and Space Science},
  year = {2016},
  volume = {3},
  number = {2},
  pages = {78--87},
  doi = {10.1002/2014EA000045/full}
}
Jing Y, Shi J, Wang T and Sussmann R ({2014}), "Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution", ATMOSPHERE., DEC, {2014}. Vol. {5}({4}), pp. 870-888.
Abstract: Satellite measurements of the spatiotemporal distributions of
atmospheric CO2 concentrations are a key component for better
understanding global carbon cycle characteristics. Currently, several
satellite instruments such as the Greenhouse gases Observing SATellite
(GOSAT), SCanning Imaging Absorption Spectrometer for Atmospheric
CHartographY (SCIAMACHY), and Orbiting Carbon Observatory-2 can be used
to measure CO2 column-averaged dry air mole fractions. However, because
of cloud effects, a single satellite can only provide limited CO2 data,
resulting in significant uncertainty in the characterization of the
spatiotemporal distribution of atmospheric CO2 concentrations. In this
study, a new physical data fusion technique is proposed to combine the
GOSAT and SCIAMACHY measurements. On the basis of the fused dataset, a
gap-filling method developed by modeling the spatial correlation
structures of CO2 concentrations is presented with the goal of
generating global land CO2 distribution maps with high spatiotemporal
resolution. The results show that, compared with the single satellite
dataset (i.e., GOSAT or SCIAMACHY), the global spatial coverage of the
fused dataset is significantly increased (reaching up to approximately
20, and the temporal resolution is improved by two or three times.
The spatial coverage and monthly variations of the generated global CO2
distributions are also investigated. Comparisons with ground-based Total
Carbon Column Observing Network (TCCON) measurements reveal that CO2
distributions based on the gap-filling method show good agreement with
TCCON records despite some biases. These results demonstrate that the
fused dataset as well as the gap-filling method are rather effective to
generate global CO2 distribution with high accuracies and high
spatiotemporal resolution.
BibTeX:
@article{jing14a,
  author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing and Sussmann, Ralf},
  title = {Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution},
  journal = {ATMOSPHERE},
  year = {2014},
  volume = {5},
  number = {4},
  pages = {870--888},
  doi = {10.3390/atmos5040870}
}
Jing Y, Shi J and Wang T ({2014}), "FUSION OF SPACE-BASED CO2 PRODUCTS AND ITS COMPARISON WITH OTHER AVAILABLE CO2 ESTIMATES", In 2014 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS). , pp. 2363-2366.
Abstract: Currently, ascertaining and quantifying the global distribution of
carbon dioxide from space-based measurements are greatly valuable for
understanding the causes of global warming and predicting the tendency
of climate change. Nevertheless, the number of valid XCO2 data points
from a single space-based sensor is generally limited on the earth.
Based on this problem, a fused XCO2 dataset is used to generate a
continuous spatio-temporal distribution of global CO2 concentration by
combining GOSAT with SCIAMACHY in this study. And this dataset is also
compared with a data assimilation system Carbon Tracker as well as
ground-based TCCON sites. The results reveal that the spatial coverage
of the fused data is wider than individual space-based XCO2 measurements
(GOSAT or SCIAMCHY) on the global scale. Meanwhile, compared to that of
GOSAT or SCIAMACHY, the correlation between the fused data and Carbon
Tracker is relatively better. In addition, the fused data show a good
agreement with CO2 retrieval of ACOS and BESD as well as that of TCCON
sites although a little biases exist.
BibTeX:
@inproceedings{jing14b,
  author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing},
  title = {FUSION OF SPACE-BASED CO2 PRODUCTS AND ITS COMPARISON WITH OTHER AVAILABLE CO2 ESTIMATES},
  booktitle = {2014 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS)},
  year = {2014},
  pages = {2363--2366},
  note = {IEEE Joint International Geoscience and Remote Sensing Symposium (IGARSS) / 35th Canadian Symposium on Remote Sensing, Quebec City, CANADA, JUL 13-18, 2014},
  doi = {10.1109/IGARSS.2014.6946946}
}
Jing Y, Wang T and Shi J ({2014}), "TOWARD ACCURATE XCO2 LEVEL 2 MEASUREMENTS BY COMBINING DIFFERENT CO2 RETRIEVALS FROM GOSAT AND SCIAMACHY", In 2014 THIRD INTERNATIONAL WORKSHOP ON EARTH OBSERVATION AND REMOTE SENSING APPLICATIONS (EORSA 2014).
Abstract: Carbon dioxide (CO2) is one of the most important anthropogenic
greenhouse gases causing global warming. Although various space-based
observations have been used to derive and identify regional and global
distribution of CO2 source and sink, uncertainties and biases are still
subsistent. A high spatial and temporal resolution is important to
remove the CO2 uncertainties and biases. In this study, an improved
ensemble median algorithm is developed by fully accounting for the
variation of XCO2 on synoptic timescales. Based on this, XCO2 data sets
from the improved method and EMMA are compared in terms of their
spatiotemporal distributions and correlations. Meanwhile, XCO2
measurements from three TCCON sites are used to compare with these two
datasets. The results reveal that although there is a good correlation
between the XCO2 from improved method and that of EMMA at annual scale,
large discrepancies can be still detected at most places over the world.
It seems that a higher time resolution is necessary to remove the
outliers. In addition, the season cycle of the two methods is generally
in agreement with ground measurements. However, our improved method
shows less divergence compared to that of EMMA at three ground sites. To
some extent, these results proved the effectiveness of our new method
and thus demonstrated the necessity for refining the Level 2 XCO2
measurements at a shorter time averaging period.
BibTeX:
@inproceedings{jing14c,
  author = {Jing, Yingying and Wang, Tianxing and Shi, Jiancheng},
  editor = {Weng, Q and Gamba, P and Xian, G and Wang, G and Zhu, J},
  title = {TOWARD ACCURATE XCO2 LEVEL 2 MEASUREMENTS BY COMBINING DIFFERENT CO2 RETRIEVALS FROM GOSAT AND SCIAMACHY},
  booktitle = {2014 THIRD INTERNATIONAL WORKSHOP ON EARTH OBSERVATION AND REMOTE SENSING APPLICATIONS (EORSA 2014)},
  year = {2014},
  note = {3rd International Workshop on Earth Observation and Remote Sensing Applications (EORSA), Changsha, PEOPLES R CHINA, JUN 11-14, 2014}
}
Jing Y, Shi J and Wang T ({2015}), "EVALUATION AND COMPARISON OF ATMOSPHERIC CO2 CONCENTRATIONS FROM MODELS AND SATELLITE RETRIEVALS", In 2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS). , pp. 2202-2205.
Abstract: In recent years, global warming caused by increased atmospheric CO2 has
greatly drawn widespread attention from the public. Although satellite
observations and model-simulation offer us two effective approaches to
monitor and assess the global atmospheric CO2, quantification of the
differences between these two different CO2 data is not fully
investigated yet. In this paper, these CO2 products including satellite
observations and model-simulation are inter-compared in terms of
magnitude and their spatiotemporal distributions. The results reveal
that these CO2 data from different data source show a good agreement all
over the world, whereas many discrepancies still exist between satellite
observations and model-simulation, especially in the Northern Sphere.
BibTeX:
@inproceedings{jing15a,
  author = {Jing, Yingying and Shi, Jiancheng and Wang, Tianxing},
  title = {EVALUATION AND COMPARISON OF ATMOSPHERIC CO2 CONCENTRATIONS FROM MODELS AND SATELLITE RETRIEVALS},
  booktitle = {2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS)},
  year = {2015},
  pages = {2202--2205},
  note = {IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, ITALY, JUL 26-31, 2015}
}
Jing Y, Wang T, Zhang P, Chen L, Xu N and Ma Y (2018), "Global Atmospheric CO2 Concentrations Simulated by GEOS-Chem: Comparison with GOSAT, Carbon Tracker and Ground-Based Measurements", Atmosphere. Vol. 9(5), pp. 175.
BibTeX:
@article{jing18a,
  author = {Jing, Yingying and Wang, Tianxing and Zhang, Peng and Chen, Lin and Xu, Na and Ma, Ya},
  title = {Global Atmospheric CO2 Concentrations Simulated by GEOS-Chem: Comparison with GOSAT, Carbon Tracker and Ground-Based Measurements},
  journal = {Atmosphere},
  year = {2018},
  volume = {9},
  number = {5},
  pages = {175},
  url = {https://www.mdpi.com/2073-4433/9/5/175/htm}
}
Jones LA, Kimball JS, Reichle RH, Madani N, Glassy J, Ardizzone JV, Colliander A, Cleverly J, Desai AR, Eamus D, Euskirchen ES, Hutley L, Macfarlane C and Scott RL ({2017}), "The SMAP Level 4 Carbon Product for Monitoring Ecosystem Land-Atmosphere CO2 Exchange", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING., NOV, {2017}. Vol. {55}({11}), pp. 6517-6532.
Abstract: The National Aeronautics and Space Administration's Soil Moisture Active
Passive (SMAP) mission Level 4 Carbon (L4C) product provides model
estimates of the Net Ecosystem CO2 exchange (NEE) incorporating SMAP
soil moisture information. The L4C product includes NEE, computed as
total ecosystem respiration less gross photosynthesis, at a daily time
step posted to a 9-km global grid by plant functional type. Component
carbon fluxes, surface soil organic carbon stocks, underlying
environmental constraints, and detailed uncertainty metrics are also
included. The L4C model is driven by the SMAP Level 4 Soil Moisture data
assimilation product, with additional inputs from the Goddard Earth
Observing System, Version 5 weather analysis, and Moderate Resolution
Imaging Spectroradiometer satellite vegetation data. The L4C data record
extends from March 31, 2015 to present with ongoing production and 8-12
day latency. Comparisons against concurrent global CO2 eddy flux tower
measurements, satellite solar-induced canopy florescence, and other
independent observation benchmarks show favorable L4C performance and
accuracy, capturing the dynamic biosphere response to recent weather
anomalies. Model experiments and L4C spatiotemporal variability were
analyzed to understand the independent value of soil moisture and SMAP
observations relative to other sources of input information. This
analysis highlights the potential for microwave observations to inform
models where soil moisture strongly controls land CO2 flux variability;
however, skill improvement relative to flux towers is not yet
discernable within the relatively short validation period. These results
indicate that SMAP provides a unique and promising capability for
monitoring the linked global terrestrial water and carbon cycles.
BibTeX:
@article{jones17a,
  author = {Jones, Lucas A. and Kimball, John S. and Reichle, Rolf H. and Madani, Nima and Glassy, Joe and Ardizzone, Joe V. and Colliander, Andreas and Cleverly, James and Desai, Ankur R. and Eamus, Derek and Euskirchen, Eugenie S. and Hutley, Lindsay and Macfarlane, Craig and Scott, Russell L.},
  title = {The SMAP Level 4 Carbon Product for Monitoring Ecosystem Land-Atmosphere CO2 Exchange},
  journal = {IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING},
  year = {2017},
  volume = {55},
  number = {11},
  pages = {6517--6532},
  doi = {10.1109/TGRS.2017.2729343}
}
Kanakidou M, Dameris M, Elbern H, Beekmann M, Konovalov IB, Nieradzik L, Strunk A and Krol MC ({2011}), "Synergistic Use of Retrieved Trace Constituent Distributions and Numerical Modelling", In REMOTE SENSING OF TROPOSPHERIC COMPOSITION FROM SPACE. , pp. 451-492. Springer.
BibTeX:
@incollection{kanakidou11a,
  author = {Kanakidou, Maria and Dameris, Martin and Elbern, Hendrik and Beekmann, Matthias and Konovalov, Igor B. and Nieradzik, Lars and Strunk, Achim and Krol, Maarten C.},
  editor = {Burrows, JP and Platt, U and Borrell, P},
  title = {Synergistic Use of Retrieved Trace Constituent Distributions and Numerical Modelling},
  booktitle = {REMOTE SENSING OF TROPOSPHERIC COMPOSITION FROM SPACE},
  publisher = {Springer},
  year = {2011},
  pages = {451--492},
  doi = {10.1007/978-3-642-14791-3\_9}
}
Kang J-S, Kalnay E, Liu J, Fung I, Miyoshi T and Ide K ({2011}), "``Variable localization'' in an ensemble Kalman filter: Application to the carbon cycle data assimilation", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 12, {2011}. Vol. {116}
Abstract: In ensemble Kalman filter, space localization is used to reduce the
impact of long-distance sampling errors in the ensemble estimation of
the forecast error covariance. When two variables are not physically
correlated, their error covariance is still estimated by the ensemble
and, therefore, it is dominated by sampling errors. We introduce a
``variable localization'' method, zeroing out such covariances between
unrelated variables to the problem of assimilating carbon dioxide
concentrations into a dynamical model using the local ensemble transform
Kalman filter (LETKF) in an observing system simulation experiments
(OSSE) framework. A system where meteorological and carbon variables are
simultaneously assimilated is used to estimate surface carbon fluxes
that are not directly observed. A range of covariance structures are
explored for the LETKF, with emphasis on configurations allowing nonzero
error covariance between carbon variables and the wind field, which
affects transport of atmospheric CO2, but not between CO2 and the other
meteorological variables. Such variable localization scheme zeroes out
the background error covariance among prognostic variables that are not
physically related, thus reducing sampling errors. Results from the
identical twin experiments show that the performance in the estimation
of surface carbon fluxes obtained using variable localization is much
better than that using a standard full covariance approach. The relative
improvement increases when the surface fluxes change with time and model
error becomes significant.
BibTeX:
@article{kang11a,
  author = {Kang, Ji-Sun and Kalnay, Eugenia and Liu, Junjie and Fung, Inez and Miyoshi, Takemasa and Ide, Kayo},
  title = {``Variable localization'' in an ensemble Kalman filter: Application to the carbon cycle data assimilation},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JD014673}
}
Kang J-S, Kalnay E, Miyoshi T, Liu J and Fung I ({2012}), "Estimation of surface carbon fluxes with an advanced data assimilation methodology", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 19, {2012}. Vol. {117}
Abstract: We perform every 6 h a simultaneous data assimilation of surface CO2
fluxes and atmospheric CO2 concentrations along with meteorological
variables using the Local Ensemble Transform Kalman Filter (LETKF)
within an Observing System Simulation Experiments framework. In this
paper, we focus on the impact of advanced variance inflation methods and
vertical localization of column CO2 data on the analysis of CO2. With
both additive inflation and adaptive multiplicative inflation, we are
able to obtain encouraging multiseasonal analyses of surface CO2 fluxes
in addition to atmospheric CO2 and meteorological analyses. Furthermore,
we examine strategies for vertical localization in the assimilation of
simulated CO2 from GOSAT that has nearly uniform sensitivity from the
surface to the upper troposphere. Since atmospheric CO2 is forced by
surface fluxes, its short-term variability should be largest near the
surface. We take advantage of this by updating observed changes only
into the lower tropospheric CO2 rather than into the full column. This
results in a more accurate analysis of CO2 in terms of both RMS error
and spatial patterns. Assimilating synthetic CO2 ground-based
observations and CO2 retrievals from GOSAT and AIRS with the enhanced
LETKF, we obtain an accurate estimation of the evolving surface fluxes
even in the absence of any a priori information. We also test the system
with a longer assimilation window and find that a short window with an
efficient treatment for wind uncertainty is beneficial to flux
inversion. Since this study assumes a perfect forecast model, future
research will explore the impact of model errors. Citation: Kang, J.-S.,
E. Kalnay, T. Miyoshi, J. Liu, and I. Fung (2012), Estimation of surface
carbon fluxes with an advanced data assimilation methodology, J.
Geophys. Res., 117, D24101, doi: 10.1029/2012JD018259.
BibTeX:
@article{kang12a,
  author = {Kang, Ji-Sun and Kalnay, Eugenia and Miyoshi, Takemasa and Liu, Junjie and Fung, Inez},
  title = {Estimation of surface carbon fluxes with an advanced data assimilation methodology},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2012JD018259}
}
Karion A, Sweeney C, Tans P and Newberger T ({2010}), "AirCore: An Innovative Atmospheric Sampling System", JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY., NOV, {2010}. Vol. {27}({11}), pp. 1839-1853.
Abstract: This work describes the Air Core, a simple and innovative atmospheric
sampling system. The AirCore used in this study is a 150-m-long
stainless steel tube, open at one end and closed at the other, that
relies on positive changes in ambient pressure for passive sampling of
the atmosphere. The Air Core evacuates while ascending to a high
altitude and collects a sample of the ambient air as it descends. It is
sealed upon recovery and measured with a continuous analyzer for trace
gas mole fraction. The Air Core tubing can be shaped into a variety of
configurations to accommodate any sampling platform; for the testing
done in this work it was shaped into a 0,75-m-diameter coil.
Measurements of CO(2) and CH(4) mole fractions in laboratory tests
indicate a repeatability and lack of bias to better than 0.07 ppm (one
sigma) for CO, and 0.4 ppb for CH(4) under various conditions.
Comparisons of AirCore data with flask data from aircraft flights
indicate a standard deviation of differences of 0.3 ppm and 5 ppb for
CO(2) and CH(4), respectively, with no apparent bias. Accounting for
longitudinal mixing, the expected measurement resolution for CO2 is 110
m at sea level, 260 m at 8000 m. and 1500 m at 20 000 m ASL after 3 h of
storage, decreasing to 170, 390, and 2300 m, after 12 h. Validation
tests confirm that the AirCore is a robust sampling device for many
species on a variety of platforms, including balloons, unmanned aerial
vehicles (UAVs), and aircraft.
BibTeX:
@article{karion10a,
  author = {Karion, Anna and Sweeney, Colm and Tans, Pieter and Newberger, Timothy},
  title = {AirCore: An Innovative Atmospheric Sampling System},
  journal = {JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY},
  year = {2010},
  volume = {27},
  number = {11},
  pages = {1839--1853},
  doi = {10.1175/2010JTECHA1448.1}
}
Kassem II, Joshi P, Sigler V, Heckathorn S and Wang Q ({2008}), "Effect of Elevated CO2 and Drought on Soil Microbial Communities Associated with Andropogon gerardii", JOURNAL OF INTEGRATIVE PLANT BIOLOGY., NOV, {2008}. Vol. {50}({11}), pp. 1406-1415.
Abstract: Our understanding of the effects of elevated atmospheric CO2, singly and
in combination with other environmental changes, on plant-soil
interactions is incomplete. Elevated CO2 effects on C-4 plants, though
smaller than on C-3 species, are mediated mostly via decreased stomatal
conductance and thus water loss. Therefore, we characterized the
interactive effect of elevated CO2 and drought on soil microbial
communities associated with a dominant C-4 prairie grass, Andropogon
gerardii Vitman. Elevated CO2 and drought both affected resources
available to the soil microbial community. For example, elevated CO2
increased the soil C:N ratio and water content during drought, whereas
drought alone decreased both. Drought significantly decreased soil
microbial biomass. In contrast, elevated CO2 increased biomass while
ameliorating biomass decreases that were induced under drought. Total
and active direct bacterial counts and carbon substrate use (overall use
and number of used sources) increased significantly under elevated CO2.
Denaturing gradient gel electrophoresis analysis revealed that drought
and elevated CO2, singly and combined, did not affect the soil bacteria
community structure. We conclude that elevated CO2 alone increased
bacterial abundance and microbial activity and carbon use, probably in
response to increased root exudation. Elevated CO2 also limited
drought-related impacts on microbial activity and biomass, which likely
resulted from decreased plant water use under elevated CO2. These are
among the first results showing that elevated CO2 and drought work in
opposition to modulate plant-associated soil-bacteria responses, which
should then influence soil resources and plant and ecosystem function.
BibTeX:
@article{kassem08a,
  author = {Kassem, Issmat I. and Joshi, Puneet and Sigler, Von and Heckathorn, Scott and Wang, Qi},
  title = {Effect of Elevated CO2 and Drought on Soil Microbial Communities Associated with Andropogon gerardii},
  journal = {JOURNAL OF INTEGRATIVE PLANT BIOLOGY},
  year = {2008},
  volume = {50},
  number = {11},
  pages = {1406--1415},
  doi = {10.1111/j.1744-7909.2008.00752.x}
}
Kavitha M and Nair PR ({2016}), "Region-dependent seasonal pattern of methane over Indian region as observed by SCIAMACHY", ATMOSPHERIC ENVIRONMENT., APR, {2016}. Vol. {131}, pp. 316-325.
Abstract: The column averaged mixing ratio of methane (XCH4) from SCanning Imaging
Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY)
on-board satellite ENVISAT has been used to study its regional pattern
and seasonal cycle over Indian region for the period 2003-2009. XCH4
varies from 1740 to 1890 ppbv over Indian region with distinct spatial
and temporal features. The peak values are observed in monsoon and post
monsoon and minimum in winter months, except over southern Peninsular
India which shows the distinctly different seasonal behavior with peak
in October/November. The mean background level of XCH4 over Indian
region is estimated as similar to 1795 ppbv. While regional patterns are
strongly associated with livestock distribution, wetland emissions,
including rice fields, the seasonal variations in XCH4 are predominantly
associated with the rice cultivation as revealed by analysis of NDVI.
(C) 2016 Elsevier Ltd. All rights reserved.
BibTeX:
@article{kavitha16a,
  author = {Kavitha, M. and Nair, Prabha R.},
  title = {Region-dependent seasonal pattern of methane over Indian region as observed by SCIAMACHY},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2016},
  volume = {131},
  pages = {316--325},
  doi = {10.1016/j.atmosenv.2016.02.008}
}
Kavitha M and Nair PR ({2017}), "SCIAMACHY observed changes in the column mixing ratio of methane over the Indian region and a comparison with global scenario", ATMOSPHERIC ENVIRONMENT., OCT, {2017}. Vol. {166}, pp. 454-466.
Abstract: The trends in the column averaged mixing ratio of methane (XCH4) over
the Indian region during 2003 2009 periods were studied using the
SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY
(SCIAMACHY) observations. Considering the sensor degradation, the trends
were analyzed for 2003 to 2005 and 2006 to 2009 separately. Over India,
the trend in XCH4 varied from 5.2 to 7.6 ppb per year after 2005,
exhibiting a 2-4 fold increase compared to 2003-2005. While the increase
over Northern parts of India is attributed to increasing CH4 emissions
from rice cultivation and livestock population, those over Southern
regions are due to increased oil and gas mining activities. A comparison
of these trends with those over most of the hotspot regions over the
globe revealed that those regions exhibited higher growth rates of XCH4
compared to Indian regions during 2006-2009. The seasonal patterns of
XCH4 and near-surface CH4 at selected global network stations were also
examined in detail. This analysis revealed hemispheric difference and
varying seasonal patterns suggesting the inhomogeneous vertical
distribution of CH4. The observed differences in the seasonal patterns
of near-surface CH4 and XCH4 suggest that the surface emissions need not
replicate at higher altitudes due to long-range transport, the boundary
layer meteorology and lifetime of CH4 in the atmosphere. (C) 2017
Elsevier Ltd. All rights reserved.
BibTeX:
@article{kavitha17a,
  author = {Kavitha, M. and Nair, Prabha R.},
  title = {SCIAMACHY observed changes in the column mixing ratio of methane over the Indian region and a comparison with global scenario},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2017},
  volume = {166},
  pages = {454--466},
  doi = {10.1016/j.atmosenv.2017.07.044}
}
Keeling R and Manning A (2014), "5.15 - Studies of Recent Changes in Atmospheric O2\ Content", In Treatise on Geochemistry (Second Edition). , pp. 385-404. Elsevier.
Abstract: Abstract A very close coupling exists between changes in atmospheric O2\ and CO2\ concentrations, owing to the chemistry of photosynthesis, respiration, and combustion. The coupling is not perfect, however, because CO2\ variations are partially buffered by reactions involving the inorganic carbon system in seawater, which has no effect on O2. Measurements over the past two decades document variations in O2\ on a range of space and time scales, including a long-term decrease driven mostly by fossil fuel burning and seasonal cycles driven by exchanges with the land biosphere and the oceans. In this chapter, these and other features seen in the measurements are described, also discussing variations in the tracer `atmospheric potential oxygen,' which is a linear combination of O2\ and CO2\ designed to be insensitive to exchanges from the land biosphere and thereby sensitive mostly to oceanic processes. Challenges associated with measuring variations in O2\ are addressed, and various applications of the observations are discussed, including quantifying the magnitude of the global land and ocean carbon sinks and testing ocean biogeochemical models. An updated budget for global carbon sinks based on O2\ measurements from the Scripps O2\ program is presented for the decades of the 1990s and 2000s.
BibTeX:
@incollection{keeling14a,
  author = {R.F. Keeling and A.C. Manning},
  editor = {Holland, Heinrich D. and Turekian, Karl K.},
  title = {5.15 - Studies of Recent Changes in Atmospheric O2\ Content},
  booktitle = {Treatise on Geochemistry (Second Edition)},
  publisher = {Elsevier},
  year = {2014},
  pages = {385--404},
  url = {https://www.sciencedirect.com/science/article/pii/B9780080959757004204},
  doi = {10.1016/B978-0-08-095975-7.00420-4}
}
Keppel-Aleks G, Wennberg PO and Schneider T ({2011}), "Sources of variations in total column carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({8}), pp. 3581-3593.
Abstract: Observations of gradients in the total CO(2) column, < CO(2)>, are
expected to provide improved constraints on surface fluxes of CO(2).
Here we use a general circulation model with a variety of prescribed
carbon fluxes to investigate how variations in < CO(2)> arise. On
diurnal scales, variations are small and are forced by both local fluxes
and advection. On seasonal scales, gradients are set by the north-south
flux distribution. On synoptic scales, variations arise due to
large-scale eddy-driven disturbances of the meridional gradient. In this
case, because variations in < CO(2)> are tied to synoptic activity,
significant correlations exist between < CO(2)> and dynamical tracers.
We illustrate how such correlations can be used to describe the
north-south gradients of < CO(2)> and the underlying fluxes on
continental scales. These simulations suggest a novel analysis framework
for using column observations in carbon cycle science.
BibTeX:
@article{keppel-aleks11a,
  author = {Keppel-Aleks, G. and Wennberg, P. O. and Schneider, T.},
  title = {Sources of variations in total column carbon dioxide},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2011},
  volume = {11},
  number = {8},
  pages = {3581--3593},
  doi = {10.5194/acp-11-3581-2011}
}
Keppel-Aleks G, Wennberg PO, Washenfelder RA, Wunch D, Schneider T, Toon GC, Andres RJ, Blavier JF, Connor B, Davis KJ, Desai AR, Messerschmidt J, Notholt J, Roehl CM, Sherlock V, Stephens BB, Vay SA and Wofsy SC ({2012}), "The imprint of surface fluxes and transport on variations in total column carbon dioxide", BIOGEOSCIENCES. Vol. {9}({3}), pp. 875-891.
Abstract: New observations of the vertically integrated CO2 mixing ratio,
aYCO(2)aY (c), from ground-based remote sensing show that variations in
CO(2)aY (c) are primarily determined by large-scale flux patterns. They
therefore provide fundamentally different information than observations
made within the boundary layer, which reflect the combined influence of
large-scale and local fluxes. Observations of both aYCO(2)aY (c) and CO2
concentrations in the free troposphere show that large-scale spatial
gradients induce synoptic-scale temporal variations in aYCO(2)aY (c) in
the Northern Hemisphere midlatitudes through horizontal advection.
Rather than obscure the signature of surface fluxes on atmospheric CO2,
these synoptic-scale variations provide useful information that can be
used to reveal the meridional flux distribution. We estimate the
meridional gradient in aYCO(2)aY (c) from covariations in aYCO(2)aY (c)
and potential temperature, theta, a dynamical tracer, on synoptic
timescales to evaluate surface flux estimates commonly used in carbon
cycle models. We find that simulations using Carnegie Ames Stanford
Approach (CASA) biospheric fluxes underestimate both the aYCO(2)aY (c)
seasonal cycle amplitude throughout the Northern Hemisphere midlatitudes
and the meridional gradient during the growing season. Simulations using
CASA net ecosystem exchange (NEE) with increased and phase-shifted
boreal fluxes better fit the observations. Our simulations suggest that
climatological mean CASA fluxes underestimate boreal growing season NEE
(between 45-65A degrees N) by ˜40%. We describe the implications for
this large seasonal exchange on inference of the net Northern Hemisphere
terrestrial carbon sink.
BibTeX:
@article{keppel-aleks12a,
  author = {Keppel-Aleks, G. and Wennberg, P. O. and Washenfelder, R. A. and Wunch, D. and Schneider, T. and Toon, G. C. and Andres, R. J. and Blavier, J. -F. and Connor, B. and Davis, K. J. and Desai, A. R. and Messerschmidt, J. and Notholt, J. and Roehl, C. M. and Sherlock, V. and Stephens, B. B. and Vay, S. A. and Wofsy, S. C.},
  title = {The imprint of surface fluxes and transport on variations in total column carbon dioxide},
  journal = {BIOGEOSCIENCES},
  year = {2012},
  volume = {9},
  number = {3},
  pages = {875--891},
  doi = {10.5194/bg-9-875-2012}
}
Keppel-Aleks G, Wennberg PO, O'Dell CW and Wunch D ({2013}), "Towards constraints on fossil fuel emissions from total column carbon dioxide", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({8}), pp. 4349-4357.
Abstract: We assess the large-scale, top-down constraints on regional fossil fuel
emissions provided by observations of atmospheric total column CO2,
X-CO2. Using an atmospheric general circulation model (GCM) with
underlying fossil emissions, we determine the influence of regional
fossil fuel emissions on global X-CO2 fields. We quantify the regional
contrasts between source and upwind regions and probe the sensitivity of
atmospheric X-CO2 to changes in fossil fuel emissions. Regional fossil
fuel X-CO2 contrasts can exceed 0.7 ppm based on 2007 emission
estimates, but have large seasonal variations due to biospheric fluxes.
Contamination by clouds reduces the discernible fossil signatures.
Nevertheless, our simulations show that atmospheric fossil X-CO2 can be
tied to its source region and that changes in the regional XCO2
contrasts scale linearly with emissions. We test the GCM results against
X-CO2 data from the GOSAT satellite. Regional X-CO2 contrasts in GOSAT
data generally scale with the predictions from the GCM, but the
comparison is limited by the moderate precision of and relatively few
observations from the satellite. We discuss how this approach may be
useful as a policy tool to verify national fossil emissions, as it
provides an independent, observational constraint.
BibTeX:
@article{keppel-aleks13a,
  author = {Keppel-Aleks, G. and Wennberg, P. O. and O'Dell, C. W. and Wunch, D.},
  title = {Towards constraints on fossil fuel emissions from total column carbon dioxide},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {8},
  pages = {4349--4357},
  doi = {10.5194/acp-13-4349-2013}
}
Kim MG (2011), "Errors in mixed layer heights over North America: a multi-model comparison". Thesis at: University of Waterloo.
BibTeX:
@mastersthesis{kim11a,
  author = {Kim, Myung Gwang},
  title = {Errors in mixed layer heights over North America: a multi-model comparison},
  school = {University of Waterloo},
  year = {2011},
  url = {https://uwspace.uwaterloo.ca/handle/10012/5968}
}
Kim J, Kim HM and Cho C-H (2012), "Application of Carbon Tracking System based on ensemble Kalman Filter on the diagnosis of Carbon Cycle in Asia", Atmosphere. Vol. 22(4), pp. 415-427.
BibTeX:
@article{kim12a,
  author = {Kim, JinWoong and Kim, Hyun Mee and Cho, Chun-Ho},
  title = {Application of Carbon Tracking System based on ensemble Kalman Filter on the diagnosis of Carbon Cycle in Asia},
  journal = {Atmosphere},
  year = {2012},
  volume = {22},
  number = {4},
  pages = {415--427},
  url = {http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=KSHHDL_2012_v22n4_415}
}
Kim J, Kim HM and Cho C-H ({2014}), "The effect of optimization and the nesting domain on carbon flux analyses in Asia using a carbon tracking system based on the ensemble Kalman filter", ASIA-PACIFIC JOURNAL OF ATMOSPHERIC SCIENCES., MAY, {2014}. Vol. {50}({3}), pp. 327-344.
Abstract: To estimate the surface carbon flux in Asia and investigate the effect
of the nesting domain on carbon flux analyses in Asia, two experiments
with different nesting domains were conducted using the CarbonTracker
developed by the National Oceanic and Atmospheric Administration.
CarbonTracker is an inverse modeling system that uses an ensemble Kalman
filter (EnKF) to estimate surface carbon fluxes from surface CO2
observations. One experiment was conducted with a nesting domain
centered in Asia and the other with a nesting domain centered in North
America. Both experiments analyzed the surface carbon fluxes in Asia
from 2001 to 2006. The results showed that prior surface carbon fluxes
were underestimated in Asia compared with the optimized fluxes. The
optimized biosphere fluxes of the two experiments exhibited roughly
similar spatial patterns but different magnitudes. Weekly cumulative
optimized fluxes showed more diverse patterns than the prior fluxes,
indicating that more detailed flux analyses were conducted during the
optimization. The nesting domain in Asia produced a detailed estimate of
the surface carbon fluxes in Asia and exhibited better agreement with
the CO2 observations. Finally, the simulated background atmospheric CO2
concentrations in the experiment with the nesting domain in Asia were
more consistent with the observed CO2 concentrations than those in the
experiment with the nesting domain in North America. The results of this
study suggest that surface carbon fluxes in Asia can be estimated more
accurately using an EnKF when the nesting domain is centered in Asian
regions.
BibTeX:
@article{kim14a,
  author = {Kim, Jinwoong and Kim, Hyun Mee and Cho, Chun-Ho},
  title = {The effect of optimization and the nesting domain on carbon flux analyses in Asia using a carbon tracking system based on the ensemble Kalman filter},
  journal = {ASIA-PACIFIC JOURNAL OF ATMOSPHERIC SCIENCES},
  year = {2014},
  volume = {50},
  number = {3},
  pages = {327--344},
  doi = {10.1007/s13143-014-0020-y}
}
Kim J, Kim HM and Cho CH ({2014}), "Influence of CO2 observations on the optimized CO2 flux in an ensemble Kalman filter", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({24}), pp. 13515-13530.
Abstract: In this study, the effect of CO2 observations on an analysis of surface
CO2 flux was calculated using an influence matrix in the CarbonTracker,
which is an inverse modeling system for estimating surface CO2 flux
based on an ensemble Kalman filter. The influence matrix represents a
sensitivity of the analysis to observations. The experimental period was
from January 2000 to December 2009. The diagonal element of the
influence matrix (i.e., analysis sensitivity) is globally 4.8% on
average, which implies that the analysis extracts 4.8% of the
information from the observations and 95.2% from the background each
assimilation cycle. Because the surface CO2 flux in each week is
optimized by 5 weeks of observations, the cumulative impact over 5 weeks
is 19.1 much greater than 4.8 %. The analysis sensitivity is
inversely proportional to the number of observations used in the
assimilation, which is distinctly apparent in continuous observation
categories with a sufficient number of observations. The time series of
the globally averaged analysis sensitivities shows seasonal variations,
with greater sensitivities in summer and lower sensitivities in winter,
which is attributed to the surface CO2 flux uncertainty. The
time-averaged analysis sensitivities in the Northern Hemisphere are
greater than those in the tropics and the Southern Hemisphere. The trace
of the influence matrix (i.e., information content) is a measure of the
total information extracted from the observations. The information
content indicates an imbalance between the observation coverage in North
America and that in other regions. Approximately half of the total
observational information is provided by continuous observations, mainly
from North America, which indicates that continuous observations are the
most informative and that comprehensive coverage of additional
observations in other regions is necessary to estimate the surface CO2
flux in these areas as accurately as in North America.
BibTeX:
@article{kim14b,
  author = {Kim, J. and Kim, H. M. and Cho, C. -H.},
  title = {Influence of CO2 observations on the optimized CO2 flux in an ensemble Kalman filter},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {24},
  pages = {13515--13530},
  doi = {10.5194/acp-14-13515-2014}
}
Kim H, Kim HM, Kim J and Cho C-H (2016), "A Comparison of the Atmospheric CO2 Concentrations Obtained by an Inverse Modeling System and Passenger Aircraft Based Measurement", Atmosphere. Vol. 26(3), pp. 387-400.
BibTeX:
@article{kim16a,
  author = {Hyunjung Kim and Hyun Mee Kim and Jinwoong Kim and Chun-Ho Cho},
  title = {A Comparison of the Atmospheric CO2 Concentrations Obtained by an Inverse Modeling System and Passenger Aircraft Based Measurement},
  journal = {Atmosphere},
  year = {2016},
  volume = {26},
  number = {3},
  pages = {387--400},
  url = {http://www.j-komes.or.kr/xml/07935/07935.pdf}
}
Kim J, Kim HM, Cho C-H, Boo K-O, Jacobson AR, Sasakawa M, Machida T, Arshinov M and Fedoseev N ({2017}), "Impact of Siberian observations on the optimization of surface CO2 flux", ATMOSPHERIC CHEMISTRY AND PHYSICS., FEB 24, {2017}. Vol. {17}({4}), pp. 2881-2899.
Abstract: To investigate the effect of additional CO2 observations in the Siberia
region on the Asian and global surface CO2 flux analyses, two
experiments using different observation data sets were performed for
2000-2009. One experiment was conducted using a data set that includes
additional observations of Siberian tower measurements (Japan-Russia
Siberian Tall Tower Inland Observation Network: JR-STATION), and the
other experiment was conducted using a data set without the above
additional observations. The results show that the global balance of the
sources and sinks of surface CO2 fluxes was maintained for both
experiments with and without the additional observations. While the
magnitude of the optimized surface CO2 flux uptake and flux uncertainty
in Siberia decreased from 1.17 +/- 0.93 to 0.77 +/- 0.70 PgC yr(-1), the
magnitude of the optimized surface CO2 flux uptake in the other regions
(e.g., Europe) of the Northern Hemisphere (NH) land increased for the
experiment with the additional observations, which affect the
longitudinal distribution of the total NH sinks. This change was mostly
caused by changes in the magnitudes of surface CO2 flux in June and
July. The observation impact measured by uncertainty reduction and
self-sensitivity tests shows that additional observations provide useful
information on the estimated surface CO2 flux. The average uncertainty
reduction of the conifer forest of Eurasian boreal (EB) is 29.1% and
the average self-sensitivities at the JR-STATION sites are approximately
60% larger than those at the towers in North America. It is expected
that the Siberian observations play an important role in estimating
surface CO2 flux in the NH land (e.g., Siberia and Europe) in the
future.
BibTeX:
@article{kim17a,
  author = {Kim, Jinwoong and Kim, Hyun Mee and Cho, Chun-Ho and Boo, Kyung-On and Jacobson, Andrew R. and Sasakawa, Motoki and Machida, Toshinobu and Arshinov, Mikhail and Fedoseev, Nikolay},
  title = {Impact of Siberian observations on the optimization of surface CO2 flux},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {4},
  pages = {2881--2899},
  doi = {10.5194/acp-17-2881-2017}
}
Kim H, Kim HM, Kim J and Cho C-H (2017), "Effect of data assimilation parameters on the optimized surface CO2 flux in Asia", Asia-Pacific Journal of Atmospheric Sciences., September, 2017. , pp. 1-17.
Abstract: In this study, CarbonTracker, an inverse modeling system based on the ensemble Kalman filter, was used to evaluate the effects of data assimilation parameters (assimilation window length and ensemble size) on the estimation of surface CO2 fluxes in Asia. Several experiments with different parameters were conducted, and the results were verified using CO2 concentration observations. The assimilation window lengths tested were 3, 5, 7, and 10 weeks, and the ensemble sizes were 100, 150, and 300. Therefore, a total of 12 experiments using combinations of these parameters were conducted. The experimental period was from January 2006 to December 2009. Differences between the optimized surface CO2 fluxes of the experiments were largest in the Eurasian Boreal (EB) area, followed by Eurasian Temperate (ET) and Tropical Asia (TA), and were larger in boreal summer than in boreal winter. The effect of ensemble size on the optimized biosphere flux is larger than the effect of the assimilation window length in Asia, but the importance of them varies in specific regions in Asia. The optimized biosphere flux was more sensitive to the assimilation window length in EB, whereas it was sensitive to the ensemble size as well as the assimilation window length in ET. The larger the ensemble size and the shorter the assimilation window length, the larger the uncertainty (i.e., spread of ensemble) of optimized surface CO2 fluxes. The 10-week assimilation window and 300 ensemble size were the optimal configuration for CarbonTracker in the Asian region based on several verifications using CO2 concentration measurements.
BibTeX:
@article{kim17b,
  author = {Kim, Hyunjung and Kim, Hyun Mee and Kim, Jinwoong and Cho, Chun-Ho},
  title = {Effect of data assimilation parameters on the optimized surface CO2 flux in Asia},
  journal = {Asia-Pacific Journal of Atmospheric Sciences},
  year = {2017},
  pages = {1--17},
  doi = {10.1007/s13143-017-0049-9}
}
Kim H, Kim HM, Cho M, Park J and Kim D-H ({2018}), "Development of the Aircraft CO2 Measurement Data Assimilation System to Improve the Estimation of Surface CO2 Fluxes Using an Inverse Modeling System", ATMOSPHERE-KOREA., JUN, {2018}. Vol. {28}({2}), pp. {113-121}.
Abstract: In order to monitor greenhouse gases including CO2, various types of
surface-, aircraft-, and satellite-based measurement projects have been
conducted. These data help understand the variations of greenhouse gases
and are used in atmospheric inverse modeling systems to simulate surface
fluxes for greenhouse gases. CarbonTracker is a system for estimating
surface CO2 flux, using an atmospheric inverse modeling method, based on
only surface observation data. Because of the insufficient surface
observation data available for accurate estimation of the surface CO2
flux, additional observations would be required. In this study, a system
that assimilates aircraft CO2 measurement data in CarbonTracker
(CT2013B) is developed, and the estimated results from this data
assimilation system are evaluated. The aircraft CO2 measurement data
used are obtained from the Comprehensive Observation Network for Trace
gases by the Airliner (CONTRAIL) project. The developed system includes
the preprocessor of the raw observation data, the observation operator,
and the ensemble Kalman filter (EnKF) data assimilation process. After
preprocessing the raw data, the modeled value corresponding spatially
and temporally to each observation is calculated using the observation
operator. These modeled values and observations are then averaged in
space and time, and used in the EnKF data assimilation process. The
modeled values are much closer to the observations and show smaller
biases and root-mean-square errors, after the assimilation of the
aircraft CO2 measurement data. This system could also be used to
assimilate other aircraft CO2 measurement data in CarbonTracker.
BibTeX:
@article{kim18a,
  author = {Kim, Hyunjung and Kim, Hyun Mee and Cho, Minkwang and Park, Jun and Kim, Dae-Hui},
  title = {Development of the Aircraft CO2 Measurement Data Assimilation System to Improve the Estimation of Surface CO2 Fluxes Using an Inverse Modeling System},
  journal = {ATMOSPHERE-KOREA},
  year = {2018},
  volume = {28},
  number = {2},
  pages = {113-121},
  doi = {{10.14191/Atmos.2018.28.2.113}}
}
King AW, Andres RJ, Davis KJ, Hafer M, Hayes DJ, Huntzinger DN, de Jong B, Kurz WA, McGuire AD, Vargas R, Wei Y, West TO and Woodall CW ({2015}), "North America's net terrestrial CO2 exchange with the atmosphere 1990-2009", BIOGEOSCIENCES. Vol. {12}({2}), pp. 399-414.
Abstract: Scientific understanding of the global carbon cycle is required for
developing national and international policy to mitigate fossil fuel CO2
emissions by managing terrestrial carbon uptake. Toward that
understanding and as a contribution to the REgional Carbon Cycle
Assessment and Processes (RECCAP) project, this paper provides a
synthesis of net land-atmosphere CO2 exchange for North America (Canada,
United States, and Mexico) over the period 1990-2009. Only CO2 is
considered, not methane or other greenhouse gases. This synthesis is
based on results from three different methods: atmospheric inversion,
inventory-based methods and terrestrial biosphere modeling. All methods
indicate that the North American land surface was a sink for atmospheric
CO2, with a net transfer from atmosphere to land. Estimates ranged from
-890 to -280 TgC yr(-1), where the mean of atmospheric inversion
estimates forms the lower bound of that range (a larger land sink) and
the inventory-based estimate using the production approach the upper (a
smaller land sink). This relatively large range is due in part to
differences in how the approaches represent trade, fire and other
disturbances and which ecosystems they include. Integrating across
estimates, ``best'' estimates (i.e., measures of central tendency) are
-472 +/- 281 TgC yr(-1) based on the mean and standard deviation of the
distribution and -360 TgC yr(-1) (with an interquartile range of -496 to
-337) based on the median. Considering both the fossil fuel emissions
source and the land sink, our analysis shows that North America was,
however, a net contributor to the growth of CO2 in the atmosphere in the
late 20th and early 21st century. With North America's mean annual
fossil fuel CO2 emissions for the period 1990-2009 equal to 1720 Tg C
yr(-1) and assuming the estimate of -472 TgC yr(-1) as an approximation
of the true terrestrial CO2 sink, the continent's source : sink ratio
for this time period was 1720 : 472, or nearly 4 : 1.
BibTeX:
@article{king15a,
  author = {King, A. W. and Andres, R. J. and Davis, K. J. and Hafer, M. and Hayes, D. J. and Huntzinger, D. N. and de Jong, B. and Kurz, W. A. and McGuire, A. D. and Vargas, R. and Wei, Y. and West, T. O. and Woodall, C. W.},
  title = {North America's net terrestrial CO2 exchange with the atmosphere 1990-2009},
  journal = {BIOGEOSCIENCES},
  year = {2015},
  volume = {12},
  number = {2},
  pages = {399--414},
  doi = {10.5194/bg-12-399-2015}
}
Kivi R and Heikkinen P ({2016}), "Fourier transform spectrometer measurements of column CO2 at Sodankyla, Finland", GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS. Vol. {5}({2}), pp. 271-279.
Abstract: Fourier transform spectrometer (FTS) observations at Sodankyla, Finland
(67.4 degrees N, 26.6 degrees E) have been performed since early 2009.
The FTS instrument is participating in the Total Carbon Column Observing
Network (TCCON) and has been optimized to measure abundances of the key
greenhouse gases in the atmosphere. Sodankyla is the only TCCON station
in the Fennoscandia region. Here we report the measured CO2 time series
over a 7-year period (2009-2015) and provide a description of the FTS
system and data processing at Sodankyla. We find the lowest monthly
column CO2 values in August and the highest monthly values during the
February-May season. Inter-annual variability is the highest in the
June-September period, which correlates with the growing season. During
the time period of FTS measurements from 2009 to 2015, we have observed
a 2.2 +/- 0.2 ppm increase per year in column CO2. The monthly mean
column CO2 values have exceeded 400 ppm level for the first time in
February 2014.
BibTeX:
@article{kivi16a,
  author = {Kivi, Rigel and Heikkinen, Pauli},
  title = {Fourier transform spectrometer measurements of column CO2 at Sodankyla, Finland},
  journal = {GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS},
  year = {2016},
  volume = {5},
  number = {2},
  pages = {271--279},
  doi = {10.5194/gi-5-271-2016}
}
Klappenbach F, Bertleff M, Kostinek J, Hase F, Blumenstock T, Agusti-Panareda A, Razinger M and Butz A ({2015}), "Accurate mobile remote sensing of XCO2 and XCH4 latitudinal transects from aboard a research vessel", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({12}), pp. 5023-5038.
Abstract: A portable Fourier transform spectrometer (FTS), model EM27/SUN, was
deployed onboard the research vessel Polarstern to measure the
column-average dry air mole fractions of carbon dioxide (XCO2) and
methane (XCH4) by means of direct sunlight absorption spectrometry. We
report on technical developments as well as data calibration and
reduction measures required to achieve the targeted accuracy of
fractions of a percent in retrieved XCO2 and XCH4 while operating the
instrument under field conditions onboard the moving platform during a
6-week cruise on the Atlantic from Cape Town (South Africa, 34 degrees
S, 18 degrees E; 5 March 2014) to Bremerhaven (Germany, 54 degrees N, 19
degrees E; 14 April 2014). We demonstrate that our solar tracker
typically achieved a tracking precision of better than 0.05 degrees
toward the center of the sun throughout the ship cruise which
facilitates accurate XCO2 and XCH4 retrievals even under harsh ambient
wind conditions. We define several quality filters that screen spectra,
e.g., when the field of view was partially obstructed by ship structures
or when the lines-of-sight crossed the ship exhaust plume. The
measurements in clean oceanic air, can be used to characterize a
spurious air-mass dependency. After the campaign, deployment of the
spectrometer alongside the TCCON (Total Carbon Column Observing Network)
instrument at Karlsruhe, Germany, allowed for determining a calibration
factor that makes the entire campaign record traceable to World
Meteorological Organization (WMO) standards. Comparisons to observations
of the GOSAT satellite and concentration fields modeled by the European
Centre for Medium-Range Weather Forecasts (ECMWF) Copernicus Atmosphere
Monitoring Service (CAMS) demonstrate that the observational setup is
well suited to provide validation opportunities above the ocean and
along interhemispheric transects.
BibTeX:
@article{klappenbach15a,
  author = {Klappenbach, F. and Bertleff, M. and Kostinek, J. and Hase, F. and Blumenstock, T. and Agusti-Panareda, A. and Razinger, M. and Butz, A.},
  title = {Accurate mobile remote sensing of XCO2 and XCH4 latitudinal transects from aboard a research vessel},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {12},
  pages = {5023--5038},
  doi = {10.5194/amt-8-5023-2015}
}
Klappenbach FW (2016), "Mobile spectroscopic measurements of atmospheric carbon dioxide and methane". Thesis at: Karlsruher Instituts für Technologie.
BibTeX:
@phdthesis{klappenbach16a,
  author = {Klappenbach, Friedrich Wilhelm},
  title = {Mobile spectroscopic measurements of atmospheric carbon dioxide and methane},
  school = {Karlsruher Instituts für Technologie},
  year = {2016},
  url = {https://d-nb.info/1114312576/34}
}
Koffi EN, Rayner PJ, Scholze M, Chevallier F and Kaminski T ({2013}), "Quantifying the constraint of biospheric process parameters by CO2 concentration and flux measurement networks through a carbon cycle data assimilation system", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({21}), pp. 10555-10572.
Abstract: The sensitivity of the process parameters of the Biosphere Energy
Transfer HYdrology (BETHY) model to choices of atmospheric concentration
network, high frequency terrestrial fluxes, and the choice of flux
measurement network is investigated by using a carbon cycle data
assimilation system. We use BETHY-generated fluxes as a proxy of flux
measurements. Results show that monthly mean or low-frequency
observations of CO2 concentration provide strong constraints on
parameters relevant for net flux (NEP) but only weak constraints for
parameters controlling gross fluxes. The use of high-frequency CO2
concentration observations, which has led to great refinement of spatial
scales in inversions of net flux, adds little to the observing system in
the Carbon Cycle Data Assimilation System (CCDAS) case. This unexpected
result is explained by the fact that the stations of the CO2
concentration network we use are not well placed to measure such high
frequency signals. Indeed, CO2 concentration sensitivities relevant for
such high frequency fluxes are found to be largely confined in the
vicinity of the corresponding fluxes, and are therefore not well
observed by background monitoring stations. In contrast, our results
clearly show the potential of flux measurements to better constrain the
model parameters relevant for gross primary productivity (GPP) and net
primary productivity (NPP). Given uncertainties in the spatial
description of ecosystem functions, we recommend a combined observing
strategy.
BibTeX:
@article{koffi13a,
  author = {Koffi, E. N. and Rayner, P. J. and Scholze, M. and Chevallier, F. and Kaminski, T.},
  title = {Quantifying the constraint of biospheric process parameters by CO2 concentration and flux measurement networks through a carbon cycle data assimilation system},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {21},
  pages = {10555--10572},
  doi = {10.5194/acp-13-10555-2013}
}
Kondo M, Ichii K, Takagi H and Sasakawa M ({2015}), "Comparison of the data-driven top-down and bottom-up global terrestrial CO2 exchanges: GOSAT CO2 inversion and empirical eddy flux upscaling", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., JUL, {2015}. Vol. {120}({7}), pp. 1226-1245.
Abstract: We examined the consistency between terrestrial biosphere fluxes
(terrestrial CO2 exchanges) from data-driven top-down (GOSAT CO2
inversion) and bottom-up (empirical eddy flux upscaling based on a
support vector regression (SVR) model) approaches over 42 global
terrestrial regions from June 2009 to October 2011. Seasonal variations
of the biosphere fluxes by the two approaches agreed well in boreal and
temperate regions across the Northern Hemisphere. Both fluxes also
exhibited strong anomalous signals in response to contrasting anomalous
spring temperatures observed in North America and boreal Eurasia. This
indicates that the CO2 concentration data integrated in the GOSAT
inversion and the meteorological and vegetation data in the SVR models
are equally effective in producing spatiotemporal variations of
biosphere flux. Meanwhile, large differences in seasonality were found
in subtropical and tropical South America, South Asia, and Africa. The
GOSAT inversion showed seasonal variations that pivoted around CO2
neutral, while the SVR model showed seasonal variations that tended
toward CO2 sink. Thus, a large difference in CO2 budget was identified
between the two approaches in subtropical and tropical regions across
the Southern Hemisphere. Examination of the integrated data revealed
that the large tropical sink of CO2 by the SVR model was an artifact due
to the underrepresented biosphere fluxes predicted by limited eddy flux
data for tropical biomes. Because of the global coverage of CO2
concentration data, the GOSAT inversion provides better estimates of
continental CO2 flux than the SVR model in the Southern Hemisphere.
BibTeX:
@article{kondo15a,
  author = {Kondo, Masayuki and Ichii, Kazuhito and Takagi, Hiroshi and Sasakawa, Motoki},
  title = {Comparison of the data-driven top-down and bottom-up global terrestrial CO2 exchanges: GOSAT CO2 inversion and empirical eddy flux upscaling},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2015},
  volume = {120},
  number = {7},
  pages = {1226--1245},
  doi = {10.1002/2014JG002866}
}
Konopka P, Ploeger F, Tao M and Riese M ({2017}), "Regionally Resolved Diagnostic of Transport: A Simplified Forward Model for CO2", JOURNAL OF THE ATMOSPHERIC SCIENCES., AUG, {2017}. Vol. {74}({8}), pp. 2689-2700.
Abstract: Simply diagnostic tools are useful for understanding transport processes
in complex chemistry transport models (CTMs). For this purpose, a
combined use of the airmass origin fractions (AOFs) and regionally
resolved mean ages (RMAs) is presented. This approach merges the concept
of the origin of air with the well-known theory of the mean age of air
(AoA) for different regions covering the whole Earth. The authors show
how the AoA calculated relative to Earth's surface can be decomposed
into regionally resolved components (i.e., into RMAs). Using both AOFs
and RMAs, the authors discuss differences in the seasonality of
transport from the Northern and Southern Hemispheres into the tropical
tropopause layer (TTL), the asymmetries of the interhemispheric
exchange, and differences in relation to the continental or oceanic
origin of air. Furthermore, a simplified transport model for a
chemically passive species (tracer) is formulated that has some
potential to approximate the full transport within a CTM. This analytic
approach uses the AOFs as well as the RMAs as parameters to propagate a
tracer prescribed on Earth's surface (lower boundary condition). This
method is exactly valid for sources that change linearly with time in
each of the considered regions. The authors analyze how well this
approach approximates the propagation of CO2 from the planetary boundary
layer (PBL) into the whole atmosphere. The CO2 values in the PBL are
specified by the CarbonTracker dataset. The authors discuss how this
approach can be used for inverse modeling of CO2.
BibTeX:
@article{konopka17a,
  author = {Konopka, Paul and Ploeger, Felix and Tao, Mengchu and Riese, Martin},
  title = {Regionally Resolved Diagnostic of Transport: A Simplified Forward Model for CO2},
  journal = {JOURNAL OF THE ATMOSPHERIC SCIENCES},
  year = {2017},
  volume = {74},
  number = {8},
  pages = {2689--2700},
  doi = {10.1175/JAS-D-16-0367.1}
}
Xing-Xia K, Zhang M-G and Peng Z (2013), "Numerical Simulation of CO2 Concentrations in East Asia with RAMS-CMAQ", Atmospheric and Oceanic Science Letters. Vol. 6(4), pp. 179-184.
BibTeX:
@article{kou13a,
  author = {Kou Xing-Xia and Zhang, Mei-Gen and Peng, Zhen},
  title = {Numerical Simulation of CO2 Concentrations in East Asia with RAMS-CMAQ},
  journal = {Atmospheric and Oceanic Science Letters},
  year = {2013},
  volume = {6},
  number = {4},
  pages = {179--184}
}
Kou X, Zhang M, Peng Z and Wang Y ({2015}), "Assessment of the biospheric contribution to surface atmospheric CO2 concentrations over East Asia with a regional chemical transport model", ADVANCES IN ATMOSPHERIC SCIENCES., MAR, {2015}. Vol. {32}({3}), pp. 287-300.
Abstract: A regional chemical transport model, RAMS-CMAQ, was employed to assess
the impacts of biosphere-atmosphere C-2 exchange on seasonal variations
in atmospheric C-2 concentrations over East Asia. Simulated C-2
concentrations were compared with observations at 12 surface stations
and the comparison showed they were generally in good agreement. Both
observations and simulations suggested that surface C-2 over East Asia
features a summertime trough due to biospheric absorption, while in some
urban areas surface C-2 has a distinct summer peak, which could be
attributed to the strong impact from anthropogenic emissions. Analysis
of the model results indicated that biospheric fluxes and fossil-fuel
emissions are comparably important in shaping spatial distributions of
C-2 near the surface over East Asia. Biospheric flux plays an important
role in the prevailing spatial pattern of C-2 enhancement and reduction
on the synoptic scale due to the strong seasonality of biospheric C-2
flux. The elevation of C-2 levels by the biosphere during winter was
found to be larger than 5 ppm in North China and Southeast China, and
during summertime a significant depletion (a (c) 3/4 7 ppm) occurred in
most areas, except for the Indo-China Peninsula where positive bioflux
values were found.
BibTeX:
@article{kou15a,
  author = {Kou, Xingxia and Zhang, Meigen and Peng, Zhen and Wang, Yinghong},
  title = {Assessment of the biospheric contribution to surface atmospheric CO2 concentrations over East Asia with a regional chemical transport model},
  journal = {ADVANCES IN ATMOSPHERIC SCIENCES},
  year = {2015},
  volume = {32},
  number = {3},
  pages = {287--300},
  doi = {10.1007/s00376-014-4059-6}
}
Kou X, Tian X, Zhang M, Peng Z and Zhang X ({2017}), "Accounting for CO2 Variability over East Asia with a Regional Joint Inversion System and Its Preliminary Evaluation", JOURNAL OF METEOROLOGICAL RESEARCH., OCT, {2017}. Vol. {31}({5}), pp. 834-851.
Abstract: A regional surface carbon dioxide (CO2) flux inversion system, the
Tan-Tracker-Region, was developed by incorporating an assimilation
scheme into the Community Multiscale Air Quality (CMAQ) regional
chemical transport model to resolve fine-scale CO2 variability over East
Asia. The proper orthogonal decomposition-based ensemble
four-dimensional variational data assimilation approach (POD-4DVar) is
the core algorithm for the joint assimilation framework, and
simultaneous assimilations of CO2 concentrations and surface CO2 fluxes
are applied to help reduce the uncertainty in initial CO2
concentrations. A persistence dynamical model was developed to describe
the evolution of the surface CO2 fluxes and help avoid the
``signal-to-noise'' problem; thus, CO2 fluxes could be estimated as a
whole at the model grid scale, with better use of observation
information. The performance of the regional inversion system was
evaluated through a group of single-observation-based observing system
simulation experiments (OSSEs). The results of the experiments suggest
that a reliable performance of Tan-Tracker-Region is dependent on
certain assimilation parameter choices, for example, an optimized window
length of approximately 3 h, an ensemble size of approximately 100, and
a covariance localization radius of approximately 320 km. This is
probably due to the strong diurnal variation and spatial heterogeneity
in the fine-scale CMAQ simulation, which could affect the performance of
the regional inversion system. In addition, because all observations can
be artificially obtained in OSSEs, the performance of Tan-Tracker-Region
was further evaluated through different densities of the artificial
observation network in different CO2 flux situations. The results
indicate that more observation sites would be useful to systematically
improve the estimation of CO2 concentration and flux in large areas over
the model domain. The work presented here forms a foundation for future
research in which a thorough estimation of CO2 flux variability over
East Asia could be performed with the regional inversion system.
BibTeX:
@article{kou17a,
  author = {Kou, Xingxia and Tian, Xiangjun and Zhang, Meigen and Peng, Zhen and Zhang, Xiaoling},
  title = {Accounting for CO2 Variability over East Asia with a Regional Joint Inversion System and Its Preliminary Evaluation},
  journal = {JOURNAL OF METEOROLOGICAL RESEARCH},
  year = {2017},
  volume = {31},
  number = {5},
  pages = {834--851},
  doi = {10.1007/s13351-017-6149-8}
}
Kountouris P, Gerbig C, Totsche KU, Dolman AJ, Meesters AGCA, Broquet G, Maignan F, Gioli B, Montagnani L and Helfter C ({2015}), "An objective prior error quantification for regional atmospheric inverse applications", BIOGEOSCIENCES. Vol. {12}({24}), pp. 7403-7421.
Abstract: Assigning proper prior uncertainties for inverse modelling of CO2 is of
high importance, both to regularise the otherwise ill-constrained
inverse problem and to quantitatively characterise the magnitude and
structure of the error between prior and `true' flux. We use surface
fluxes derived from three biosphere models - VPRM, ORCHIDEE, and 5PM -
and compare them against daily averaged fluxes from 53 eddy covariance
sites across Europe for the year 2007 and against repeated aircraft flux
measurements encompassing spatial transects. In addition we create
synthetic observations using modelled fluxes instead of the observed
ones to explore the potential to infer prior uncertainties from
model-model residuals. To ensure the realism of the synthetic data
analysis, a random measurement noise was added to the modelled tower
fluxes which were used as reference. The temporal autocorrelation time
for tower model-data residuals was found to be around 30 days for both
VPRM and ORCHIDEE but significantly different for the 5PM model with 70
days. This difference is caused by a few sites with large biases between
the data and the 5PM model. The spatial correlation of the model-data
residuals for all models was found to be very short, up to few tens of
kilometres but with uncertainties up to 100 % of this estimation.
Propagating this error structure to annual continental scale yields an
uncertainty of 0.06 Gt C and strongly underestimates uncertainties
typically used from atmospheric inversion systems, revealing another
potential source of errors. Long spatial e-folding correlation lengths
up to several hundreds of kilometres were determined when synthetic data
were used. Results from repeated aircraft transects in south-western
France are consistent with those obtained from the tower sites in terms
of spatial autocorrelation (35 km on average) while temporal
autocorrelation is markedly lower (13 days). Our findings suggest that
the different prior models have a common temporal error structure.
Separating the analysis of the statistics for the model data residuals
by seasons did not result in any significant differences of the spatial
e-folding correlation lengths.
BibTeX:
@article{kountouris15a,
  author = {Kountouris, P. and Gerbig, C. and Totsche, K. -U. and Dolman, A. J. and Meesters, A. G. C. A. and Broquet, G. and Maignan, F. and Gioli, B. and Montagnani, L. and Helfter, C.},
  title = {An objective prior error quantification for regional atmospheric inverse applications},
  journal = {BIOGEOSCIENCES},
  year = {2015},
  volume = {12},
  number = {24},
  pages = {7403--7421}
}
Kountouris P, Gerbig C, Rodenbeck C, Karstens U, Koch TF and Heimann M ({2018}), "Technical Note: Atmospheric CO2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAR 2, {2018}. Vol. {18}({4}), pp. {3027-3045}.
Abstract: Atmospheric inversions are widely used in the optimization of surface
carbon fluxes on a regional scale using information from atmospheric CO2
dry mole fractions. In many studies the prior flux uncertainty applied
to the inversion schemes does not directly reflect the true flux
uncertainties but is used to regularize the inverse problem. Here, we
aim to implement an inversion scheme using the Jena inversion system and
applying a prior flux error structure derived from a model-data residual
analysis using high spatial and temporal resolution over a full year
period in the European domain. We analyzed the performance of the
inversion system with a synthetic experiment, in which the flux
constraint is derived following the same residual analysis but applied
to the model-model mismatch. The synthetic study showed a quite good
agreement between posterior and ``true'' fluxes on European, country,
annual and monthly scales. Posterior monthly and country-aggregated
fluxes improved their correlation coefficient with the ``known truth''
by 7% compared to the prior estimates when compared to the reference,
with a mean correlation of 0.92. The ratio of the SD between the
posterior and reference and between the prior and reference was also
reduced by 33% with a mean value of 1.15. We identified temporal and
spatial scales on which the inversion system maximizes the derived
information; monthly temporal scales at around 200 km spatial resolution
seem to maximize the information gain.
BibTeX:
@article{kountouris18a,
  author = {Kountouris, Panagiotis and Gerbig, Christoph and Rodenbeck, Christian and Karstens, Ute and Koch, Thomas Frank and Heimann, Martin},
  title = {Technical Note: Atmospheric CO2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2018},
  volume = {18},
  number = {4},
  pages = {3027-3045},
  doi = {{10.5194/acp-18-3027-2018}}
}
Koven CD (2016), "Role of CO2, climate and land use in regulating the seasonal amplitude increase of carbon fluxes in terrestrial ecosystems: a multimodel analysis", Biogeosciences. Vol. 13(17), pp. 5121.
BibTeX:
@article{koven16a,
  author = {Koven, Charles D},
  title = {Role of CO2, climate and land use in regulating the seasonal amplitude increase of carbon fluxes in terrestrial ecosystems: a multimodel analysis},
  journal = {Biogeosciences},
  year = {2016},
  volume = {13},
  number = {17},
  pages = {5121},
  url = {http://search.proquest.com/openview/6b2e171c3b3e9903f77f7fd2002927a3/1?pq-origsite=gscholar&cbl=105740}
}
Kretschmer R, Gerbig C, Karstens U and Koch FT ({2012}), "Error characterization of CO2 vertical mixing in the atmospheric transport model WRF-VPRM", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({5}), pp. 2441-2458.
Abstract: One of the dominant uncertainties in inverse estimates of regional CO2
surface-atmosphere fluxes is related to model errors in vertical
transport within the planetary boundary layer (PBL). In this study we
present the results from a synthetic experiment using the atmospheric
model WRF-VPRM to realistically simulate transport of CO2 for large
parts of the European continent at 10 km spatial resolution. To
elucidate the impact of vertical mixing error on modeled CO2 mixing
ratios we simulated a month during the growing season (August 2006) with
different commonly used parameterizations of the PBL
(Mellor-Yamada-JanjiA double dagger (MYJ) and Yonsei-University (YSU)
scheme). To isolate the effect of transport errors we prescribed the
same CO2 surface fluxes for both simulations. Differences in simulated
CO2 mixing ratios (model bias) were on the order of 3 ppm during daytime
with larger values at night. We present a simple method to reduce this
bias by 70-80% when the true height of the mixed layer is known.
BibTeX:
@article{kretschmer12a,
  author = {Kretschmer, R. and Gerbig, C. and Karstens, U. and Koch, F. -T.},
  title = {Error characterization of CO2 vertical mixing in the atmospheric transport model WRF-VPRM},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2012},
  volume = {12},
  number = {5},
  pages = {2441--2458},
  doi = {10.5194/acp-12-2441-2012}
}
Kulawik SS, Jones DBA, Nassar R, Irion FW, Worden JR, Bowman KW, Machida T, Matsueda H, Sawa Y, Biraud SC, Fischer ML and Jacobson AR ({2010}), "Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({12}), pp. 5601-5623.
BibTeX:
@article{kulawik10a,
  author = {Kulawik, S. S. and Jones, D. B. A. and Nassar, R. and Irion, F. W. and Worden, J. R. and Bowman, K. W. and Machida, T. and Matsueda, H. and Sawa, Y. and Biraud, S. C. and Fischer, M. L. and Jacobson, A. R.},
  title = {Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {12},
  pages = {5601--5623},
  doi = {10.5194/acp-10-5601-2010}
}
Kulawik SS, Worden JR, Wofsy SC, Biraud SC, Nassar R, Jones DBA, Olsen ET, Jimenez R, Park S, Santoni GW, Daube BC, Pittman JV, Stephens BB, Kort EA, Osterman GB and Team T ({2013}), "Comparison of improved Aura Tropospheric Emission Spectrometer CO2 with HIPPO and SGP aircraft profile measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({6}), pp. 3205-3225.
BibTeX:
@article{kulawik13a,
  author = {Kulawik, S. S. and Worden, J. R. and Wofsy, S. C. and Biraud, S. C. and Nassar, R. and Jones, D. B. A. and Olsen, E. T. and Jimenez, R. and Park, S. and Santoni, G. W. and Daube, B. C. and Pittman, J. V. and Stephens, B. B. and Kort, E. A. and Osterman, G. B. and TES Team},
  title = {Comparison of improved Aura Tropospheric Emission Spectrometer CO2 with HIPPO and SGP aircraft profile measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {6},
  pages = {3205--3225},
  doi = {10.5194/acp-13-3205-2013}
}
Kulawik S, Wunch D, O'Dell C, Frankenberg C, Reuter M, Oda T, Chevallier F, Sherlock V, Buchwitz M, Osterman G, Miller CE, Wennberg PO, Griffith D, Morino I, Dubey MK, Deutscher NM, Notholt J, Hase F, Warneke T, Sussmann R, Robinson J, Strong K, Schneider M, De Maziere M, Shiomi K, Feist DG, Iraci LT and Wolf J ({2016}), "Consistent evaluation of ACOS-GOSAT, BESD-SCIAMACHY, CarbonTracker, and MACC through comparisons to TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({2}), pp. 683-709.
Abstract: Consistent validation of satellite CO2 estimates is a prerequisite for
using multiple satellite CO2 measurements for joint flux inversion, and
for establishing an accurate long-term atmospheric CO2 data record.
Harmonizing satellite CO2 measurements is particularly important since
the differences in instruments, observing geometries, sampling
strategies, etc. imbue different measurement characteristics in the
various satellite CO2 data products. We focus on validating model and
satellite observation attributes that impact flux estimates and CO2
assimilation, including accurate error estimates, correlated and random
errors, overall biases, biases by season and latitude, the impact of
coincidence criteria, validation of seasonal cycle phase and amplitude,
yearly growth, and daily variability. We evaluate dry-air mole fraction
(X-CO2) for Greenhouse gases Observing SATellite (GOSAT) (Atmospheric
CO2 Observations from Space, ACOS b3.5) and SCanning Imaging Absorption
spectroMeter for Atmospheric CHartographY (SCIAMACHY) (Bremen Optimal
Estimation DOAS, BESD v2.00.08) as well as the CarbonTracker (CT2013b)
simulated CO2 mole fraction fields and the Monitoring Atmospheric
Composition and Climate (MACC) CO2 inversion system (v13.1) and compare
these to Total Carbon Column Observing Network (TCCON) observations
(GGG2012/2014). We find standard deviations of 0.9, 0.9, 1.7, and 2.1
ppm vs. TCCON for CT2013b, MACC, GOSAT, and SCIAMACHY, respectively,
with the single observation errors 1.9 and 0.9 times the predicted
errors for GOSAT and SCIAMACHY, respectively. We quantify how satellite
error drops with data averaging by interpreting according to error(2) =
a(2) + b(2) / n (with n being the number of observations averaged, a the
systematic (correlated) errors, and b the random (uncorrelated) errors).
a and b are estimated by satellites, coincidence criteria, and
hemisphere. Biases at individual stations have year-to-year variability
of similar to 0.3 ppm, with biases larger than the TCCON-predicted bias
uncertainty of 0.4 ppm at many stations. We find that GOSAT and CT2013b
underpredict the seasonal cycle amplitude in the Northern Hemisphere
(NH) between 46 and 53 degrees N, MACC overpredicts between 26 and 37
ffi N, and CT2013b underpredicts the seasonal cycle amplitude in the
Southern Hemisphere (SH). The seasonal cycle phase indicates whether a
data set or model lags another data set in time. We find that the GOSAT
measurements improve the seasonal cycle phase substantially over the
prior while SCIAMACHY measurements improve the phase significantly for
just two of seven sites. The models reproduce the measured seasonal
cycle phase well except for at Lauder125HR (CT2013b) and Darwin
(MACC). We compare the variability within 1 day between TCCON and models
in JJA; there is correlation between 0.2 and 0.8 in the NH, with models
showing 10-50% the variability of TCCON at different stations and
CT2013b showing more variability than MACC. This paper highlights
findings that provide inputs to estimate flux errors in model
assimilations, and places where models and satellites need further
investigation, e.g., the SH for models and 4567 ffi N for GOSAT and
CT2013b.
BibTeX:
@article{kulawik16a,
  author = {Kulawik, Susan and Wunch, Debra and O'Dell, Christopher and Frankenberg, Christian and Reuter, Maximilian and Oda, Tomohiro and Chevallier, Frederic and Sherlock, Vanessa and Buchwitz, Michael and Osterman, Greg and Miller, Charles E. and Wennberg, Paul O. and Griffith, David and Morino, Isamu and Dubey, Manvendra K. and Deutscher, Nicholas M. and Notholt, Justus and Hase, Frank and Warneke, Thorsten and Sussmann, Ralf and Robinson, John and Strong, Kimberly and Schneider, Matthias and De Maziere, Martine and Shiomi, Kei and Feist, Dietrich G. and Iraci, Laura T. and Wolf, Joyce},
  title = {Consistent evaluation of ACOS-GOSAT, BESD-SCIAMACHY, CarbonTracker, and MACC through comparisons to TCCON},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {2},
  pages = {683--709},
  doi = {10.5194/amt-9-683-2016}
}
Kulawik SS, O'Dell C, Payne VH, Kuai L, Worden HM, Biraud SC, Sweeney C, Stephens B, Iraci LT, Yates EL and Tanaka T ({2017}), "Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations", ATMOSPHERIC CHEMISTRY AND PHYSICS., APR 27, {2017}. Vol. {17}({8}), pp. 5407-5438.
Abstract: We present two new products from near-infrared Greenhouse Gases
Observing Satellite (GOSAT) observations: lowermost tropospheric (LMT,
from 0 to 2.5 km) and upper tropospheric-stratospheric (U, above 2.5 km)
carbon dioxide partial column mixing ratios. We compare these new
products to aircraft profiles and remote surface flask measurements and
find that the seasonal and year-to-year variations in the new partial
column mixing ratios significantly improve upon the Atmospheric CO2
Observations from Space (ACOS) and GOSAT (ACOS-GOSAT) initial guess
and/or a priori, with distinct patterns in the LMT and U seasonal cycles
that match validation data. For land monthly averages, we find errors of
1.9, 0.7, and 0.8 ppm for retrieved GOSAT LMT, U, and X CO2; for ocean
monthly averages, we find errors of 0.7, 0.5, and 0.5 ppm for retrieved
GOSAT LMT, U, and X CO2. In the southern hemispheric biomass burning
season, the new partial columns show similar patterns to MODIS fire maps
and MOPITT multispectral CO for both vertical levels, despite a flat
ACOS-GOSAT prior, and a CO-CO2 emission factor comparable to published
values. The difference of LMT and U, useful for evaluation of model
transport error, has also been validated with a monthly average error of
0.8 (1.4) ppm for ocean (land). LMT is more locally influenced than U,
meaning that local fluxes can now be better separated from CO2
transported from far away.
BibTeX:
@article{kulawik17a,
  author = {Kulawik, Susan S. and O'Dell, Chris and Payne, Vivienne H. and Kuai, Le and Worden, Helen M. and Biraud, Sebastien C. and Sweeney, Colm and Stephens, Britton and Iraci, Laura T. and Yates, Emma L. and Tanaka, Tomoaki},
  title = {Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {8},
  pages = {5407--5438},
  doi = {10.5194/acp-17-5407-2017}
}
Kumar KR, Tiwari YK, Valsala V and Murtugudde R ({2014}), "On understanding the land-ocean CO2 contrast over the Bay of Bengal: A case study during 2009 summer monsoon", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., APR, {2014}. Vol. {21}({7}), pp. 5066-5075.
Abstract: Ship-based observations of atmospheric carbon dioxide (CO2)
concentration over the Bay of Bengal (BoB) between 17 July 2009 and 17
Aug 2009 offered an excellent opportunity to evaluate the land-ocean
contrast of surface CO2 and facilitated its comparison with model
simulated CO2 concentrations. Elevated values of CO2 with large
variability near the coastal region and relatively low values with
correspondingly lower variability over the open ocean suggest that this
observed CO2 variability over the ocean essentially captures the
differences in terrestrial and oceanic CO2 fluxes. Although the region
under investigation is well known for its atmospheric intraseasonal
oscillations of Indian summer monsoon during July and August, the
limited duration of observations performed from a moving ship in a
research cruise, is not able to capture any high-frequency variability
of atmospheric CO2 concentrations. But band-passed sea surface
temperature and wind anomalies do indicate strong intraseasonal
variability over the study region during the observational period. The
synoptic data, albeit quite short in duration, thus offer a clear
benchmark for abrupt variability of CO2 concentration between land and
ocean.
BibTeX:
@article{kumar14a,
  author = {Kumar, K. Ravi and Tiwari, Yogesh K. and Valsala, Vinu and Murtugudde, Raghu},
  title = {On understanding the land-ocean CO2 contrast over the Bay of Bengal: A case study during 2009 summer monsoon},
  journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
  year = {2014},
  volume = {21},
  number = {7},
  pages = {5066--5075},
  doi = {10.1007/s11356-013-2386-2}
}
Kumar KR, Valsala V, Tiwari YK, Revadekar JV, Pillai P, Chakraborty S and Murtugudde R ({2016}), "Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons", ATMOSPHERIC ENVIRONMENT., OCT, {2016}. Vol. {142}, pp. 229-237.
Abstract: In a study based on a data assimilation product of the terrestrial
biospheric fluxes of CO2 over India, the subcontinent was hypothesized
to be an anomalous source (sink) of CO2 during the active (break) spells
of rain in the summer monsoon from June to September (Valsala et al.,
2013). We test this hypothesis here by investigating intraseasonal
variability in the atmospheric CO2 concentrations over India by
utilizing a combination of ground-based and satellite observations and
model outputs. The results show that the atmospheric CO2 concentration
also varies in synchrony with the active and break spells of rainfall
with amplitude of +/- 2 ppm which is above the instrumental uncertainty
of the present day techniques of atmospheric CO2 measurements. The
result is also consistent with the signs of the Net Ecosystem Exchange
(NEE) flux anomalies estimated in our earlier work. The study thus
offers the first observational affirmation of the above hypothesis
although the data gap in the satellite measurements during monsoon
season and the limited ground-based stations over India still leaves
some uncertainty in the robust assertion of the hypothesis. The study
highlights the need to capture these subtle variabilities and their
responses to climate variability and change since it has implications
for inverse estimates of terrestrial CO2 fluxes. (C) 2016 Elsevier Ltd.
All rights reserved.
BibTeX:
@article{kumar16a,
  author = {Kumar, K. Ravi and Valsala, Vinu and Tiwari, Yogesh K. and Revadekar, J. V. and Pillai, Prasanth and Chakraborty, Supriyo and Murtugudde, Raghu},
  title = {Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2016},
  volume = {142},
  pages = {229--237},
  doi = {10.1016/j.atmosenv.2016.07.023}
}
Kurz WA, Shaw CH, Boisvenue C, Stinson G, Metsaranta J, Leckie D, Dyk A, Smyth C and Neilson ET ({2013}), "Carbon in Canada's boreal forest - A synthesis", ENVIRONMENTAL REVIEWS. Vol. {21}({4}), pp. 260-292.
Abstract: Canada's managed boreal forest, 54% of the nation's total boreal forest
area, stores 28 Pg carbon (C) in biomass, dead organic matter, and soil
pools. The net C balance is dominated by the difference of two large
continuous fluxes: C uptake (net primary production) and release during
decomposition (heterotrophic respiration). Additional releases of C can
be high in years, or in areas, that experience large anthropogenic or
natural disturbances. From 1990 to 2008, Canada's managed boreal forest
has acted as C sink of 28 Tg C year(-1), removing CO2 from the
atmosphere to replace the 17 Tg of C annually harvested and store an
additional 11 Tg of C year-1 in ecosystem C pools. A large fraction
(similar to 57 of the C harvested since 1990 remains stored in wood
products and solid waste disposal sites in Canada and abroad, replacing
C emitted from the decay or burning of wood harvested prior to 1990 and
contributing to net increases in product and landfill C pools. Wood
product use has reduced emissions in other sectors by substituting for
emission-intensive products (concrete, steel). The C balance of the
unmanaged boreal forest is currently unknown. The future C balance of
the Canadian boreal forest will affect the global atmospheric C budget
and influence the mitigation efforts required to attain atmospheric CO2
stabilization targets. The single biggest threat to C stocks is
human-caused climate change. Large C stocks have accumulated in the
boreal because decomposition is limited by cold temperatures and often
anoxic environments. Increases in temperatures and disturbance rates
could result in a large net C source during the remainder of this
century and beyond. Uncertainties about the impacts of global change
remain high, but we emphasize the asymmetry of risk: sustained
large-scale increases in productivity are unlikely to be of sufficient
magnitude to offset higher emissions from increased disturbances and
heterotrophic respiration. Reducing the uncertainties of the current and
future C balance of Canada's 270 Mha of boreal forest requires
addressing gaps in monitoring, observation, and quantification of forest
C dynamics, with particular attention to 125 Mha of unmanaged boreal
forest with extensive areas of deep organic soils, peatlands, and
permafrost containing large quantities of C that are vulnerable to
global warming.
BibTeX:
@article{kurz13a,
  author = {Kurz, W. A. and Shaw, C. H. and Boisvenue, C. and Stinson, G. and Metsaranta, J. and Leckie, D. and Dyk, A. and Smyth, C. and Neilson, E. T.},
  title = {Carbon in Canada's boreal forest - A synthesis},
  journal = {ENVIRONMENTAL REVIEWS},
  year = {2013},
  volume = {21},
  number = {4},
  pages = {260--292},
  doi = {10.1139/er-2013-0041}
}
LaFranchi BW, McFarlane KJ, Miller JB, Lehman SJ, Phillips CL, Andrews AE, Tans PP, Chen H, Liu Z, Turnbull JC, Xu X and Guilderson TP ({2016}), "Strong regional atmospheric C-14 signature of respired CO2 observed from a tall tower over the midwestern United States", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., AUG, {2016}. Vol. {121}({8}), pp. 2275-2295.
Abstract: Radiocarbon in CO2 ((CO2)-C-14) measurements can aid in discriminating
between fast (< 1 year) and slower (> 5-10 years) cycling of C between
the atmosphere and the terrestrial biosphere due to the 14C
disequilibrium between atmospheric and terrestrial C. However,
(CO2)-C-14 in the atmosphere is typically much more strongly impacted by
fossil fuel emissions of CO2, and, thus, observations often provide
little additional constraints on respiratory flux estimates at regional
scales. Here we describe a data set of (CO2)-C-14 observations from a
tall tower in northern Wisconsin (USA) where fossil fuel influence is
far enough removed that during the summer months, the biospheric
component of the (CO2)-C-14 budget dominates. We find that the
terrestrial biosphere is responsible for a significant contribution to
(CO2)-C-14 that is 2-3 times higher than predicted by the
Carnegie-Ames-Stanford approach terrestrial ecosystem model for
observations made in 2010. This likely includes a substantial
contribution from the North American boreal ecoregion, but transported
biospheric emissions from outside the model domain cannot be ruled out.
The (CO2)-C-14 enhancement also appears somewhat decreased in
observations made over subsequent years, suggesting that 2010 may be
anomalous. With these caveats acknowledged, we discuss the implications
of the observation/ model comparison in terms of possible systematic
biases in the model versus short-term anomalies in the observations.
Going forward, this isotopic signal could be exploited as an important
indicator to better constrain both the long-term carbon balance of
terrestrial ecosystems and the short-term impact of disturbance-based
loss of carbon to the atmosphere.
BibTeX:
@article{lafranchi16a,
  author = {LaFranchi, B. W. and McFarlane, K. J. and Miller, J. B. and Lehman, S. J. and Phillips, C. L. and Andrews, A. E. and Tans, P. P. and Chen, H. and Liu, Z. and Turnbull, J. C. and Xu, X. and Guilderson, T. P.},
  title = {Strong regional atmospheric C-14 signature of respired CO2 observed from a tall tower over the midwestern United States},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2016},
  volume = {121},
  number = {8},
  pages = {2275--2295},
  doi = {10.1002/2015JG003271}
}
Lan X, Tans P, Sweeney C, Andrews A, Jacobson A, Crotwell M, Dlugokencky E, Kofler J, Lang P, Thoning K and Wolter S ({2017}), "Gradients of column CO2 across North America from the NOAA Global Greenhouse Gas Reference Network", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 21, {2017}. Vol. {17}({24}), pp. 15151-15165.
Abstract: This study analyzes seasonal and spatial patterns of column carbon
dioxide (CO2) over North America, calculated from aircraft and tall
tower measurements from the NOAA Global Greenhouse Gas Reference Network
from 2004 to 2014. Consistent with expectations, gradients between the
eight regions studied are larger below 2 km than above 5 km. The 11-year
mean CO2 dry mole fraction (XCO2) in the column below similar to 330 hPa
(similar to 8 km above sea level) from NOAA's CO2 data assimilation
model, Carbon-Tracker (CT2015), demonstrates good agreement with those
calculated from calibrated measurements on aircraft and towers. Total
column XCO2 was attained by combining modeled CO2 above 330 hPa from
CT2015 with the measurements. We find large spatial gradients of total
column XCO2 from June to August, with north and northeast regions having
similar to 3 ppm stronger summer drawdown (peak-to-valley amplitude in
seasonal cycle) than the south and southwest regions. The long-term
averaged spatial gradients of total column XCO2 across North America
show a smooth pattern that mainly reflects the large-scale circulation.
We have conducted a CarbonTracker experiment to investigate the impact
of Eurasian long-range transport. The result suggests that the large
summertime Eurasian boreal flux contributes about half of the
north-south column XCO2 gradient across North America. Our results
confirm that continental-scale total column XCO2 gradients simulated by
CarbonTracker are realistic and can be used to evaluate the credibility
of some spatial patterns from satellite retrievals, such as the
long-term average of growing-season spatial patterns from satellite
retrievals reported for Europe which show a larger spatial difference
(similar to 6 ppm) and scattered hot spots.
BibTeX:
@article{lan17a,
  author = {Lan, Xin and Tans, Pieter and Sweeney, Colm and Andrews, Arlyn and Jacobson, Andrew and Crotwell, Molly and Dlugokencky, Edward and Kofler, Jonathan and Lang, Patricia and Thoning, Kirk and Wolter, Sonja},
  title = {Gradients of column CO2 across North America from the NOAA Global Greenhouse Gas Reference Network},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {24},
  pages = {15151--15165},
  doi = {10.5194/acp-17-15151-2017}
}
de lange A and Landgraf J ({2018}), "Methane profiles from GOSAT thermal infrared spectra", ATMOSPHERIC MEASUREMENT TECHNIQUES., JUN 28, {2018}. Vol. {11}({6}), pp. {3815-3828}.
Abstract: This paper discusses the retrieval of atmospheric methane profiles from
the thermal infrared band of the Japanese Greenhouse Gases Observing
Satellite (GOSAT) between 1210 and 1310 cm(-1), using the RemoTeC
analysis software. Approximately one degree of information on the
vertical methane distribution is inferred from the measurements, with
the main sensitivity at about 9 km altitude but little sensitivity to
methane in the lower troposphere. For verification, we compare the
GOSAT-TIR methane profile retrieval results with profiles from model
fields provided by the Monitoring Atmospheric Composition and Climate
(MACC) project, scaled to the total column measurements of the Total
Carbon Column Observing Network (TCCON) at ground-based measurement
sites. Without any radiometric corrections of GOSAT observations,
differences between both data sets can be as large as 10 %. To mitigate
these differences, we developed a correction scheme using a principal
component analysis of spectral fit residuals and airborne observations
of methane during the HIAPER pole-to-pole observations (HIPPO) campaign
II and III. When the correction scheme is applied, the bias in the
methane profile can be reduced to less than 2% over the whole altitude
range with respect to MACC model methane fields. Furthermore, we show
that, with this correction, the retrievals result in smooth methane
fields over land and ocean crossings and no differences can be discerned
between daytime and night-time measurements. Finally, a cloud filter is
developed for the nighttime and ocean measurements. This filter is
rooted in the GOSAT-TIR (thermal infrared) measurements and its
performance, in terms of biases, is consistent with the cloud filter
based on the GOSAT-SWIR (shortwave infrared) measurements. The TIR
filter shows a higher acceptance rate of observations than the SWIR
filter, at the cost of a higher uncertainty in the retrieved methane
profiles.
BibTeX:
@article{lange18a,
  author = {de lange, Arno and Landgraf, Jochen},
  title = {Methane profiles from GOSAT thermal infrared spectra},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2018},
  volume = {11},
  number = {6},
  pages = {3815-3828},
  doi = {{10.5194/amt-11-3815-2018}}
}
Langley B (2012), "Modelling urban forest structure and services using the urban forest effects (UFORE) model". Thesis at: University of British Columbia.
BibTeX:
@jurthesis{langley12a,
  author = {Langley, Benjamin},
  title = {Modelling urban forest structure and services using the urban forest effects (UFORE) model},
  school = {University of British Columbia},
  year = {2012},
  url = {https://open.library.ubc.ca/collections/undergraduateresearch/52966/items/1.0075544}
}
Lanso AS, Bendtsen J, Christensen JH, Sorensen LL, Chen H, Meijer HAJ and Geels C ({2015}), "Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability", BIOGEOSCIENCES. Vol. {12}({9}), pp. 2753-2772.
Abstract: Minimising the uncertainties in estimates of air-sea CO2 exchange is an
important step toward increasing the confidence in assessments of the
CO2 cycle. Using an atmospheric transport model makes it possible to
investigate the direct impact of atmospheric parameters on the air-sea
CO2 flux along with its sensitivity to, for example, short-term temporal
variability in wind speed, atmospheric mixing height and atmospheric CO2
concentration. With this study, the importance of high spatiotemporal
resolution of atmospheric parameters for the air-sea CO2 flux is
assessed for six sub-basins within the Baltic Sea and Danish inner
waters. A new climatology of surface water partial pressure of CO2
(pCO(2)(w)) has been developed for this coastal area based on available
data from monitoring stations and on-board pCO(2)(w) measuring systems.
Parameterisations depending on wind speed were applied for the transfer
velocity to calculate the air-sea CO2 flux. Two model simulations were
conducted - one including short-term variability in atmospheric CO2
(VAT), and one where it was not included (CAT).
A seasonal cycle in the air-sea CO2 flux was found for both simulations
for all sub-basins with uptake of CO2 in summer and release of CO2 to
the atmosphere in winter. During the simulated period 2005-2010, the
average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish
straits and Kattegat was 287 and 471 Gg C yr(-1) for the VAT and CAT
simulations, respectively. The obtained difference of 184 Gg C yr(-1)
was found to be significant, and thus ignoring short-term variability in
atmospheric CO2 does have a sizeable effect on the air-sea CO2 exchange.
The combination of the atmospheric model and the new pCO(2)(w) fields
has also made it possible to make an estimate of the marine part of the
Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C
yr(-1) was found for the Danish waters.
A large uncertainty is connected to the air-sea CO2 flux in particular
caused by the transfer velocity parameterisation and the applied
pCO(2)(w) climatology. However, as a significant difference of 184 Gg C
yr(-1) is obtained between the VAT and CAT simulations, the present
study underlines the importance of including short-term variability in
atmospheric CO2 concentration in future model studies of the air-sea
exchange in order to minimise the uncertainty.
BibTeX:
@article{lanso15a,
  author = {Lanso, A. S. and Bendtsen, J. and Christensen, J. H. and Sorensen, L. L. and Chen, H. and Meijer, H. A. J. and Geels, C.},
  title = {Sensitivity of the air-sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability},
  journal = {BIOGEOSCIENCES},
  year = {2015},
  volume = {12},
  number = {9},
  pages = {2753--2772},
  doi = {10.5194/bg-12-2753-2015}
}
Lanso AS, Sorensen LL, Christensen JH, Rutgersson A and Geels C ({2017}), "The influence of short-term variability in surface water pCO(2) on modelled air-sea CO2 exchange", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {69}
Abstract: Coastal seas and estuarine systems are highly variable in both time and
space and with their heterogeneity difficult to capture with
measurements. Models are useful tools in obtaining a better
spatiotemporal coverage or, at least, a better understanding of the
impacts such heterogeneity has in driving variability in coastal oceans
and estuaries. A model-based sensitivity study is constructed in this
study in order to examine the effects of short-term variability in
surface water pCO(2) on the annual air-sea CO2 exchange in coastal
regions. An atmospheric transport model formed the basis of the
modelling framework for the study of the Baltic Sea and the Danish inner
waters. Several maps of surface water pCO(2) were employed in the
modelling framework. While a monthly Baltic Sea climatology (BSC) had
already been developed, the current study further extended this with the
addition of an improved near-coastal climatology for the Danish inner
waters. Furthermore, daily surface fields of pCO(2) were obtained from a
mixed layer scheme constrained by surface measurements of pCO(2) (JENA).
Short-term variability in surface water pCO(2) was assessed by
calculating monthly mean diurnal cycles from continuous measurements of
surface water pCO(2), observed at stationary sites within the Baltic
Sea. No apparent diurnal cycle was evident in winter, but diurnal cycles
(with amplitudes up to 27 mu atm) were found from April to October. The
present study showed that the temporal resolution of surface water
pCO(2) played an influential role on the annual air-sea CO2 exchange for
the coastal study region. Hence, annual estimates of CO2 exchanges are
sensitive to variation on much shorter time scales, and this variability
should be included for any model study investigating the exchange of CO2
across the air-sea interface. Furthermore, the choice of surface pCO(2)
maps also had a crucial influence on the simulated air-sea CO2 exchange.
BibTeX:
@article{lanso17a,
  author = {Lanso, Anne Sofie and Sorensen, Lise Lotte and Christensen, Jesper H. and Rutgersson, Anna and Geels, Camilla},
  title = {The influence of short-term variability in surface water pCO(2) on modelled air-sea CO2 exchange},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2017},
  volume = {69},
  doi = {10.1080/16000889.2017.1302670}
}
Laskar AH, Lin L-C, Jiang X and Liang M-C (2018), "Distribution of CO2 in Western Pacific, Studied Using Isotope Data Made in Taiwan, OCO‐2 Satellite Retrievals, and CarbonTracker Products", Earth and Space Science.
BibTeX:
@article{laskar18a,
  author = {Amzad H. Laskar and Li-Ching Lin and Xun Jiang and Mao-Chang Liang},
  title = {Distribution of CO2 in Western Pacific, Studied Using Isotope Data Made in Taiwan, OCO‐2 Satellite Retrievals, and CarbonTracker Products},
  journal = {Earth and Space Science},
  year = {2018},
  url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018EA000415}
}
Lauvaux T, Schuh AE, Uliasz M, Richardson S, Miles N, Andrews AE, Sweeney C, Diaz LI, Martins D, Shepson PB and Davis KJ ({2012}), "Constraining the CO2 budget of the corn belt: exploring uncertainties from the assumptions in a mesoscale inverse system", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {12}({1}), pp. 337-354.
Abstract: We performed an atmospheric inversion of the CO2 fluxes over Iowa and
the surrounding states, from June to December 2007, at 20 km resolution
and weekly timescale. Eight concentration towers were used to constrain
the carbon balance in a 1000x1000 km(2) domain in this agricultural
region of the US upper midwest. The CO2 concentrations of the boundaries
derived from CarbonTracker were adjusted to match direct observations
from aircraft profiles around the domain. The regional carbon balance
ends up with a sink of 183 Tg C +/- 35 Tg C over the area for the period
June-December, 2007. Potential bias from incorrect boundary conditions
of about 0.55 ppm over the 7 months was corrected using mixing ratios
from four different aircraft profile sites operated at a weekly time
scale, acting as an additional source of uncertainty of 24 Tg C. We used
two different prior flux estimates, the SiBCrop model and the inverse
flux product from the CarbonTracker system. We show that inverse flux
estimates using both priors converge to similar posterior estimates (20
Tg C difference), in our reference inversion, but some spatial
structures from the prior fluxes remain in the posterior fluxes,
revealing the importance of the prior flux resolution and distribution
despite the large amount of atmospheric data available. The retrieved
fluxes were compared to eddy flux towers in the corn and grassland
areas, revealing an improvement in the seasonal cycles between the two
compared to the prior fluxes, despite large absolute differences due to
representation errors. The uncertainty of 34 Tg C (or 34 g C m(2)) was
derived from the posterior uncertainty obtained with our reference
inversion of about 25 to 30 Tg C and from sensitivity tests of the
assumptions made in the inverse system, for a mean carbon balance over
the region of -183 Tg C, slightly weaker than the reference. Because of
the potential large bias (similar to 24 Tg C in this case) due to choice
of background conditions, proportional to the surface but not to the
regional flux, this methodology seems limited to regions with a large
signal (sink or source), unless additional observations can be used to
constrain the boundary inflow.
BibTeX:
@article{lauvaux12a,
  author = {Lauvaux, T. and Schuh, A. E. and Uliasz, M. and Richardson, S. and Miles, N. and Andrews, A. E. and Sweeney, C. and Diaz, L. I. and Martins, D. and Shepson, P. B. and Davis, K. J.},
  title = {Constraining the CO2 budget of the corn belt: exploring uncertainties from the assumptions in a mesoscale inverse system},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2012},
  volume = {12},
  number = {1},
  pages = {337--354},
  doi = {10.5194/acp-12-337-2012}
}
Lauvaux T, Schuh AE, Bocquet M, Wu L, Richardson S, Miles N and Davis KJ ({2012}), "Network design for mesoscale inversions of CO2 sources and sinks", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {64}
Abstract: Recent instrumental deployments of regional observation networks of
atmospheric CO2 mixing ratios have been used to constrain carbon sources
and sinks using inversion methodologies. In this study, we performed
sensitivity experiments using observation sites from the Mid Continent
Intensive experiment to evaluate the required spatial density and
locations of CO2 concentration towers based on flux corrections and
error reduction analysis. In addition, we investigated the impact of
prior flux error structures with different correlation lengths and biome
information. We show here that, while the regional carbon balance
converged to similar annual estimates using only two concentration
towers over the region, additional sites were necessary to retrieve the
spatial flux distribution of our reference case (using the entire
network of eight towers). Local flux corrections required the presence
of observation sites in their vicinity, suggesting that each tower was
only able to retrieve major corrections within a hundred of kilometres
around, despite the introduction of spatial correlation lengths (similar
to 100 to 300 km) in the prior flux errors. We then quantified and
evaluated the impact of the spatial correlations in the prior flux
errors by estimating the improvement in the CO2 model-data mismatch of
the towers not included in the inversion. The overall gain across the
domain increased with the correlation length, up to 300 km, including
both biome-related and non-biome-related structures. However, the
spatial variability at smaller scales was not improved. We conclude that
the placement of observation towers around major sources and sinks is
critical for regional-scale inversions in order to obtain reliable flux
distributions in space. Sparser networks seem sufficient to assess the
overall regional carbon budget with the support of flux error
correlations, indicating that regional signals can be recovered using
hourly mixing ratios. However, the smaller spatial structures in the
posterior fluxes are highly constrained by assumed prior flux error
correlation lengths, with no significant improvement at only a few
hundreds of kilometres away from the observation sites.
BibTeX:
@article{lauvaux12b,
  author = {Lauvaux, T. and Schuh, A. E. and Bocquet, M. and Wu, L. and Richardson, S. and Miles, N. and Davis, K. J.},
  title = {Network design for mesoscale inversions of CO2 sources and sinks},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2012},
  volume = {64},
  doi = {10.3402/tellusb.v64i0.17980}
}
Lauvaux T, Miles NL, Richardson SJ, Deng A, Stauffer DR, Davis KJ, Jacobson G, Rella C, Calonder G-P and DeCola PL ({2013}), "Urban Emissions of CO2 from Davos, Switzerland: The First Real-Time Monitoring System Using an Atmospheric Inversion Technique", JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY., DEC, {2013}. Vol. {52}({12}), pp. 2654-2668.
Abstract: Anthropogenic emissions from urban areas represent 70% of the fossil
fuel carbon emitted globally according to carbon emission inventories.
The authors present here the first operational system able to monitor in
near-real time daily emission estimates, using a mesoscale atmospheric
inversion framework over the city of Davos, Switzerland, before, during,
and after the World Economic Forum 2012 Meeting (WEF-2012). Two
instruments that continuously measured atmospheric mixing ratios of
greenhouse gases (GHGs) were deployed at two locations from 23 December
2011 to 3 March 2012: one site was located in the urban area and the
other was out of the valley in the surrounding mountains. Carbon
dioxide, methane, and carbon monoxide were measured continuously at both
sites. The Weather Research and Forecasting mesoscale atmospheric model
(WRF), in four-dimensional data assimilation mode, was used to simulate
the transport of GHGs over the valley of Davos at 1.3-km resolution.
Wintertime emissions prior to the WEF-2012 were about 40% higher than
the initial annual inventory estimate, corresponding to the use of
heating fuel in the winter. Daily inverse fluxes were highly correlated
with the local climate, especially during the severe cold wave that
affected most of Europe in early February 2012. During the WEF-2012,
emissions dropped by 35% relative to the first month of the deployment,
despite similar temperatures and the presence of several thousand
participants at the meeting. On the basis of composite diurnal cycles of
hourly CO/CO2 ratios, the absence of traffic peaks during the WEF-2012
meeting indicated that change in road emissions is potentially
responsible for the observed decrease in the city emissions during the
meeting.
BibTeX:
@article{lauvaux13a,
  author = {Lauvaux, Thomas and Miles, Natasha L. and Richardson, Scott J. and Deng, Aijun and Stauffer, David R. and Davis, Kenneth J. and Jacobson, Gloria and Rella, Chris and Calonder, Gian-Paul and DeCola, Philip L.},
  title = {Urban Emissions of CO2 from Davos, Switzerland: The First Real-Time Monitoring System Using an Atmospheric Inversion Technique},
  journal = {JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY},
  year = {2013},
  volume = {52},
  number = {12},
  pages = {2654--2668},
  doi = {10.1175/JAMC-D-13-038.1}
}
Lauvaux T, Miles NL, Deng A, Richardson SJ, Cambaliza MO, Davis KJ, Gaudet B, Gurney KR, Huang J, O'Keefe D, Song Y, Karion A, Oda T, Patarasuk R, Razlivanov I, Sarmiento D, Shepson P, Sweeney C, Turnbull J and Wu K ({2016}), "High-resolution atmospheric inversion of urban CO2 emissions during the dormant season of the Indianapolis Flux Experiment (INFLUX)", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAY 27, {2016}. Vol. {121}({10}), pp. 5213-5236.
Abstract: Based on a uniquely dense network of surface towers measuring
continuously the atmospheric concentrations of greenhouse gases (GHGs),
we developed the first comprehensive monitoring systems of CO2 emissions
at high resolution over the city of Indianapolis. The urban inversion
evaluated over the 2012-2013 dormant season showed a statistically
significant increase of about 20% (from 4.5 to 5.7 MtC +/- 0.23 MtC)
compared to the Hestia CO2 emission estimate, a state-of-the-art
building-level emission product. Spatial structures in prior emission
errors, mostly undetermined, appeared to affect the spatial pattern in
the inverse solution and the total carbon budget over the entire area by
up to 15 while the inverse solution remains fairly insensitive to the
CO2 boundary inflow and to the different prior emissions (i.e., ODIAC).
Preceding the surface emission optimization, we improved the atmospheric
simulations using a meteorological data assimilation system also
informing our Bayesian inversion system through updated observations
error variances. Finally, we estimated the uncertainties associated with
undetermined parameters using an ensemble of inversions. The total CO2
emissions based on the ensemble mean and quartiles (5.26-5.91 MtC) were
statistically different compared to the prior total emissions (4.1 to
4.5 MtC). Considering the relatively small sensitivity to the different
parameters, we conclude that atmospheric inversions are potentially able
to constrain the carbon budget of the city, assuming sufficient data to
measure the inflow of GHG over the city, but additional information on
prior emission error structures are required to determine the spatial
structures of urban emissions at high resolution.
BibTeX:
@article{lauvaux16a,
  author = {Lauvaux, Thomas and Miles, Natasha L. and Deng, Aijun and Richardson, Scott J. and Cambaliza, Maria O. and Davis, Kenneth J. and Gaudet, Brian and Gurney, Kevin R. and Huang, Jianhua and O'Keefe, Darragh and Song, Yang and Karion, Anna and Oda, Tomohiro and Patarasuk, Risa and Razlivanov, Igor and Sarmiento, Daniel and Shepson, Paul and Sweeney, Colm and Turnbull, Jocelyn and Wu, Kai},
  title = {High-resolution atmospheric inversion of urban CO2 emissions during the dormant season of the Indianapolis Flux Experiment (INFLUX)},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2016},
  volume = {121},
  number = {10},
  pages = {5213--5236},
  doi = {10.1002/2015JD024473}
}
Law RM, Steele LP, Krummel PB and Zahorowski W ({2010}), "Synoptic variations in atmospheric CO2 at Cape Grim: a model intercomparison", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 810-820.
Abstract: A `TransCom' model intercomparison is used to assess how well synoptic
and diurnal variations of carbon dioxide (CO2) and 222Rn (radon) can be
modelled at the coastal site, Cape Grim, Australia. Each model was run
with prescribed fluxes and forced with analysed meteorology for
2000-2003. Twelve models were chosen for analysis based on each model's
ability to differentiate baseline CO2 concentrations from non-baseline
CO2 (influenced by regional land fluxes). Analysis focused on
non-baseline events during 2002-2003. Radon was better simulated than
CO2, indicating that a spatially uniform radon land flux is a reasonable
assumption and that regional-scale transport was adequately captured by
the models. For both radon and CO2, the ensemble model mean generally
performed better than any individual model. Two case studies highlight
common problems with the simulations. First, in summer and autumn the
Cape Grim observations are sometimes influenced by Tasmanian rather than
mainland Australian fluxes. These periods are poorly simulated.
Secondly, an event with an urban plume demonstrates how the relatively
low spatial resolution of the input CO2 fluxes limits the quality of the
simulations. Analysis of periods with below baseline concentration
indicates the possible influence of carbon uptake by winter crops in
southern mainland Australia.
BibTeX:
@article{law10a,
  author = {Law, Rachel M. and Steele, L. Paul and Krummel, Paul B. and Zahorowski, Wlodek},
  title = {Synoptic variations in atmospheric CO2 at Cape Grim: a model intercomparison},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {810--820},
  doi = {10.1111/j.1600-0889.2010.00470.x}
}
Lee TR, De Wekker SFJ, Andrews AE, Kofler J and Williams J ({2012}), "Carbon dioxide variability during cold front passages and fair weather days at a forested mountaintop site", ATMOSPHERIC ENVIRONMENT., JAN, {2012}. Vol. {46}, pp. 405-416.
Abstract: This study describes temporal carbon dioxide (CO2) changes at a new
meteorological site on a mountaintop in the Virginia Blue Ridge
Mountains during the first year of measurements. Continental mountaintop
locations are increasingly being used for CO2 monitoring, and
investigations are needed to better understand measurements made at
these locations. We focus on CO2 mixing ratio changes on days with cold
front passages and on fair weather days. Changes in CO2 mixing ratios
are largest during cold front passages outside the growing season and on
clear, fair weather days in the growing season. 67% (60 of the
frontal passages during the non-growing (growing) season have larger
postfrontal than prefrontal CO2 mixing ratios. The increase in CO2
mixing ratio around the frontal passage is short-lived and coincides
with changes in CO and O-3. The CO2 increase can therefore be used as an
additional criterion to determine the timing of frontal passages at the
mountaintop station. The CO2 increase can be explained by an
accumulation of trace gases along frontal boundaries. The magnitude and
duration of the CO2 increase is affected by the wind speed and direction
that determine the source region of the postfrontal air.
Southward-moving fronts result in the largest prolonged period of
elevated CO2, consistent with the postfrontal advection of air from the
Northeastern United States where anthropogenic contributions are
relatively large compared to other areas in the footprint of the
mountaintop station. These anthropogenic contributions to the CO2
changes are confirmed through concurrent CO measurements and output from
NOAA's CarbonTracker model. (C) 2011 Elsevier Ltd. All rights reserved.
BibTeX:
@article{lee12a,
  author = {Lee, Temple R. and De Wekker, Stephan F. J. and Andrews, Arlyn E. and Kofler, Jonathan and Williams, Jonathan},
  title = {Carbon dioxide variability during cold front passages and fair weather days at a forested mountaintop site},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2012},
  volume = {46},
  pages = {405--416},
  doi = {10.1016/j.atmosenv.2011.09.068}
}
Lee TR, De Wekker SFJ, Pal S, Andrews AE and Kofler J ({2015}), "Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY. Vol. {67}
Abstract: The variability of trace gases such as carbon monoxide (CO) at surface
monitoring stations is affected by meteorological forcings that are
particularly complicated over mountainous terrain. A detailed
understanding of the impact of meteorological forcings on trace gas
variability is challenging, but is vital to distinguish trace gas
measurements affected by local pollutant sources from measurements
representative of background mixing ratios. In the present study, we
investigate the meteorological and CO characteristics at Pinnacles
(38.61 N, 78.35 W, 1017m above mean sea level), a mountaintop monitoring
site in northwestern Virginia, USA, in the Appalachian Mountains, from
2009 to 2012, and focus on understanding the dominant meteorological
forcings affecting the CO variability on diurnal timescales. The annual
mean diurnal CO cycle shows a minimum in the morning between 0700 and
0900 LST and a maximum in the late afternoon between 1600 and 2000 LST,
with a mean (median) daily CO amplitude of 39.2 +/- 23.7 ppb (33.2 ppb).
CO amplitudes show large day-to-day variability. The largest CO
amplitudes, in which CO mixing ratios can change >100 ppb in >3 h, occur
in the presence of synoptic disturbances. Under fair weather conditions,
local-to regional-scale transport processes are found to be more
important drivers of the diurnal CO variability. On fair weather days
with northwesterly winds, boundary layer dilution causes a daytime CO
decrease, resembling the variability observed atop tall towers in flat
terrain. Fair weather days with a wind shift from the northwest to the
south are characterised by an afternoon CO increase and resemble the
variability observed at mountaintops influenced by the vertical
transport of polluted air from adjacent valleys.
BibTeX:
@article{lee15a,
  author = {Lee, Temple R. and De Wekker, Stephan F. J. and Pal, Sandip and Andrews, Arlyn E. and Kofler, Jonathan},
  title = {Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2015},
  volume = {67},
  doi = {10.3402/tellusb.v67.25659}
}
Lee S, Kim D, Im J, Lee M-I and Park Y-G ({2017}), "CO2 concentration and its spatiotemporal variation in the troposphere using multi-sensor satellite data, carbon tracker, and aircraft observations", GISCIENCE & REMOTE SENSING. Vol. {54}({4}), pp. 592-613.
Abstract: Satellite-based atmospheric CO2 observations have provided a great
opportunity to improve our understanding of the global carbon cycle.
However, thermal infrared (TIR)-based satellite observations, which are
useful for the investigation of vertical distribution and the transport
of CO2, have not yet been studied as much as the column amount products
derived from shortwave infrared data. In this study, TIR-based satellite
CO2 products - from Atmospheric Infrared Sounder, Tropospheric Emission
Spectrometer (TES), and Thermal And Near infrared Sensor for carbon
Observation - and carbon tracker mole fraction data were compared with
in situ Comprehensive Observation Network for Trace gases by AIrLiner
(CONTRAIL) data for different locations. The TES CO2 product showed the
best agreement with CONTRAIL CO2 data resulting in R-2 similar to 0.87
and root-mean-square error similar to 0.9. The vertical distribution of
CO2 derived by TES strongly depends on the geophysical characteristics
of an area. Two different climate regions (i.e., southeastern Japan and
southeastern Australia) were examined in terms of the vertical
distribution and transport of CO2. Results show that while vertical
distribution of CO2 around southeastern Japan was mainly controlled by
horizontal and vertical winds, horizontal wind might be a major factor
to control the CO2 transport around southeastern Australia. In addition,
the vertical transport of CO2 also varies by region, which is mainly
controlled by anthropogenic CO2, and horizontal and omega winds. This
study improves our understanding of vertical distribution and the
transport of CO2, both of which vary by region, using TIR-based
satellite CO2 observations and meteorological variables.
BibTeX:
@article{lee17a,
  author = {Lee, Sanggyun and Kim, Dongmin and Im, Jungho and Lee, Myong-In and Park, Young-Gyu},
  title = {CO2 concentration and its spatiotemporal variation in the troposphere using multi-sensor satellite data, carbon tracker, and aircraft observations},
  journal = {GISCIENCE & REMOTE SENSING},
  year = {2017},
  volume = {54},
  number = {4},
  pages = {592--613},
  doi = {10.1080/15481603.2017.1317120}
}
Lee TR, De Wekker SFJ and Pal S ({2018}), "The Impact of the Afternoon Planetary Boundary-Layer Height on the Diurnal Cycle of CO and Mixing Ratios at a Low-Altitude Mountaintop", BOUNDARY-LAYER METEOROLOGY., JUL, {2018}. Vol. {168}({1}), pp. {81-102}.
Abstract: Mountaintop trace-gas mixing ratios are often assumed to represent free
atmospheric values, but are affected by valley planetary boundary-layer
(PBL) air at certain times. We hypothesize that the afternoon valley-PBL
height relative to the ridgetop is important in the diurnal cycle of
mountaintop trace-gas mixing ratios. To investigate this, we use, (1)
4-years (1 January 2009-31 December 2012) of CO and mixing-ratio
measurements and supporting meteorological observations from Pinnacles
(, , 1017 m a.s.l.), which is a monitoring site in the Appalachian
Mountains, (2) regional mixing-ratio measurements, and (3) PBL heights
determined from a nearby sounding station. Results reveal that the
amplitudes of the diurnal cycles of CO and mixing ratios vary as a
function of the daytime maximum valley-PBL height relative to the
ridgetop. The mean diurnal cycle for the subset of days when the
afternoon valley-PBL height is at least 400 m below the ridgetop shows a
daytime CO mixing-ratio increase, implying the transport of PBL air from
the valley to the mountaintop. During the daytime, on days when the PBL
heights exceed the mountaintop, PBL dilution and entrainment cause CO
mixing ratios to decrease. This decrease in CO mixing ratio, especially
on days when PBL heights are at least 400 m above the ridgetop, suggests
that measurements from these days can be used as with afternoon
measurements from flat terrain in applications requiring
regionally-representative measurements.
BibTeX:
@article{lee18a,
  author = {Lee, Temple R. and De Wekker, Stephan F. J. and Pal, Sandip},
  title = {The Impact of the Afternoon Planetary Boundary-Layer Height on the Diurnal Cycle of CO and Mixing Ratios at a Low-Altitude Mountaintop},
  journal = {BOUNDARY-LAYER METEOROLOGY},
  year = {2018},
  volume = {168},
  number = {1},
  pages = {81-102},
  doi = {{10.1007/s10546-018-0343-9}}
}
Lefrançois E (2009), "Revegetation and reclamation of oil sands process-affected material using Frankia-inoculated alders: Field and greenhouse trials". Thesis at: McGill University.
BibTeX:
@mastersthesis{lefrancois09a,
  author = {Lefrançois, Elisabeth},
  title = {Revegetation and reclamation of oil sands process-affected material using Frankia-inoculated alders: Field and greenhouse trials},
  school = {McGill University},
  year = {2009},
  url = {http://digitool.library.mcgill.ca/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&forebear_coll=&user=GUEST&pds_handle=&pid=66758&con_lng=ENG&search_terms=&divType=&adjacency=N&rd_session=http://digitool.Library.McGill.CA:80/R/FT8AIQ9EGIVNJ1RIEL1L3JBY3VJSPXGBFKD2RGI227CGSACT1A-00024}
}
Lenton A, Tilbrook B, Law RM, Bakker D, Doney SC, Gruber N, Ishii M, Hoppema M, Lovenduski NS, Matear RJ, McNeil BI, Metzl N, Fletcher SEM, Monteiro PMS, Roedenbeck C, Sweeney C and Takahashi T ({2013}), "Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009", BIOGEOSCIENCES. Vol. {10}({6}), pp. 4037-4054.
Abstract: The Southern Ocean (44-75 degrees S) plays a critical role in the global
carbon cycle, yet remains one of the most poorly sampled ocean regions.
Different approaches have been used to estimate sea-air CO2 fluxes in
this region: synthesis of surface ocean observations, ocean
biogeochemical models, and atmospheric and ocean inversions. As part of
the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we
combine these different approaches to quantify and assess the magnitude
and variability in Southern Ocean sea-air CO2 fluxes between 1990-2009.
Using all models and inversions (26), the integrated median annual
sea-air CO2 flux of -0.42+/-0.07 Pg C yr(-1) for the 44-75 degrees S
region, is consistent with the -0.27+/-0.13 Pg C yr(-1) calculated using
surface observations. The circumpolar region south of 58 degrees S has a
small net annual flux (model and inversion median: -0.04+/-0.07 Pg C
yr(-1) and observations: +0.04+/-0.02 Pg C yr(-1)), with most of the net
annual flux located in the 44 to 58 degrees S circumpolar band (model
and inversion median: -0.36+/-0.09 Pg C yr(-1) and observations:
-0.35+/-0.09 Pg C yr(-1)). Seasonally, in the 44-58 degrees S region,
the median of 5 ocean biogeochemical models captures the observed
sea-air CO2 flux seasonal cycle, while the median of 11 atmospheric
inversions shows little seasonal change in the net flux. South of 58
degrees S, neither atmospheric inversions nor ocean biogeochemical
models reproduce the phase and amplitude of the observed seasonal
sea-air CO2 flux, particularly in the Austral Winter. Importantly, no
individual atmospheric inversion or ocean biogeochemical model is
capable of reproducing both the observed annual mean uptake and the
observed seasonal cycle. This raises concerns about projecting future
changes in Southern Ocean CO2 fluxes. The median interannual variability
from atmospheric inversions and ocean biogeochemical models is
substantial in the Southern Ocean; up to 25% of the annual mean flux,
with 25% of this interannual variability attributed to the region south
of 58 degrees S. Resolving long-term trends is difficult due to the
large interannual variability and short time frame (1990-2009) of this
study; this is particularly evident from the large spread in trends from
inversions and ocean biogeochemical models. Nevertheless, in the period
1990-2009 ocean biogeochemical models do show increasing oceanic uptake
consistent with the expected increase of -0.05 Pg C yr(-1) decade(-1).
In contrast, atmospheric inversions suggest little change in the
strength of the CO2 sink broadly consistent with the results of Le Quere
et al. (2007).
BibTeX:
@article{lenton13a,
  author = {Lenton, A. and Tilbrook, B. and Law, R. M. and Bakker, D. and Doney, S. C. and Gruber, N. and Ishii, M. and Hoppema, M. and Lovenduski, N. S. and Matear, R. J. and McNeil, B. I. and Metzl, N. and Fletcher, S. E. Mikaloff and Monteiro, P. M. S. and Roedenbeck, C. and Sweeney, C. and Takahashi, T.},
  title = {Sea-air CO2 fluxes in the Southern Ocean for the period 1990-2009},
  journal = {BIOGEOSCIENCES},
  year = {2013},
  volume = {10},
  number = {6},
  pages = {4037--4054},
  doi = {10.5194/bg-10-4037-2013}
}
Levinson DH and Lawrimore JH ({2008}), "State of the climate in 2007", BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY., JUL, {2008}. Vol. {89}({7, S}), pp. {10+}.
Abstract: The combined land and ocean surface temperature in 2007 fell within the
10 highest on record while the average land temperature was the warmest
since global records began in 1880. In the low to midtroposphere, the
annual global mean temperature was among the five warmest since reliable
global records began in 1958, but still cooler than the record warmest
year of 1998. For the fourth consecutive year, the annual precipitation
averaged over global land surfaces was above the long-term mean,
although the anomaly was significantly less than in 2006 when the annual
value was the eighth wettest since 1901.
The globally averaged concentration of carbon dioxide (CO2) continued to
increase in 2007, having risen to 382.7 ppm at the Mauna Loa Observatory
in Hawaii. The average rate of rise of CO2 has been 1.6 ppm yr(-1) since
1980; however, since 2000 this has increased to 1.9 ppm yr(-1). In
addition, both methane (CH4) and carbon monoxide (CO) concentrations
were also higher in 2007.
Over the oceans, global SST during 2007 showed significant departures
from the 1971-2000 climatology. Annual average upper-ocean heat content
anomalies declined between 2006 and 2007 in the eastern equatorial
Pacific and increased in off-equatorial bands in that ocean basin. These
changes were consistent with the transition from an El Nino in 2006 to a
La Nina in 2007. The global mean see level anomaly (SLA) in 2007 was 1.1
mm higher than in 2006, which is about one standard deviation below what
would be excepted from the 15-yr trend value of 3.4 mm yr(-1).
In the tropics, the Atlantic hurricane season was near normal in 2007,
although slightly more active than in 2006. In the north and south
Indian Ocean Basins, both the seasonal totals and intensity of tropical
cyclones (TC) were significantly above average, and included two
Saffir-Simpson category 5 TCs in the north Indian Ocean and a world
record rainfall amount of 5510 mm over a 3-8 day period on the island of
Reunion in the south Indian Ocean.
In the polar regions 2007 was the warmest on record for the Arctic, and
continued a general, Arctic-wide warming trend that began in the
mid-1960s. An unusually strong high pressure region in the Beaufort Sea
during summer contributed to a record minimum Arctic sea ice cover in
September. Measurements of the mass balance of glaciers and ice caps
indicate that in most of the world, glaciers and ice caps indicate that
in most of the world, glaciers are shrinking in mass. The Greenland ice
sheet experienced records in both the duration and extent of the summer
surface melt. From the continental scale as a whole the Antarctic was
warmer than average in 2007, although the Antarctic Peninsula was
considerably cooler than average. The size of the ozone hole was below
the record levels of 2006, and near the average of the past 15 yr, due
to warmer springtime temperatures in the Antarctic stratosphere.
BibTeX:
@article{levinson08a,
  author = {Levinson, D. H. and Lawrimore, J. H.},
  title = {State of the climate in 2007},
  journal = {BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY},
  year = {2008},
  volume = {89},
  number = {7, S},
  pages = {10+},
  doi = {10.1175/BAMS-89-7-StateoftheClimate}
}
Li C, Zhou L, Qin D, Liu L, Qin X, Wang Z and Ren J ({2014}), "Preliminary study of atmospheric carbon dioxide in a glacial area of the Qilian Mountains, west China", ATMOSPHERIC ENVIRONMENT., DEC, {2014}. Vol. {99}, pp. 485-490.
Abstract: Carbon dioxide represents the most important contribution to increased
radiative forcing. The preliminary results of the atmospheric carbon
dioxide mole fraction from the glacial region in the Qilian Mountains
area, in the northeast of the Qinghai-Xizang (Tibetan) Plateau during
July, 2009 to October, 2012 are presented. The annual mean CO2 mole
fractions in 2010 and 2011 were 388.4 +/- 2.7 ppm and 392.7 +/- 2.6 ppm,
respectively. These values were consistent with the CO2 mole fractions
from the WMO/GAW stations located at high altitudes. However, both the
concentration and seasonal variation were significantly lower than
stations located adjacent to megacities or economic centers at low
latitudes in eastern China. Shorter durations of photosynthesis of the
alpine vegetation system that exceeded respiration were detected at the
Qilian Mountains glacial area. The annual mean increase during the
sampling period was 2.9 ppm yr(-1) and this value was higher than the
global mean values. Anthropogenic activities in the cities adjacent to
the Qilian Mountains may have important influences on the CO2 mole
fractions, especially in summer, when north and north-north-west winds
are typical. (C) 2014 Elsevier Ltd. All rights reserved.
BibTeX:
@article{li14a,
  author = {Li, Chuanjin and Zhou, Lingxi and Qin, Dahe and Liu, Lixin and Qin, Xiang and Wang, Zebin and Ren, Jiawen},
  title = {Preliminary study of atmospheric carbon dioxide in a glacial area of the Qilian Mountains, west China},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2014},
  volume = {99},
  pages = {485--490},
  doi = {10.1016/j.atmosenv.2014.10.020}
}
Li R, Zhang M, Chen L, Kou X and Skorokhod A ({2017}), "CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements", ATMOSPHERIC ENVIRONMENT., JUL, {2017}. Vol. {160}, pp. 176-185.
Abstract: Satellite observations are widely used in global CO2 assimilations, but
their quality for use in regional assimilation systems has not yet been
thoroughly determined. Validation of satellite observations and model
simulations of CO2 is crucial for carbon flux inversions. In this study,
we focus on evaluating the uncertainties of model simulations and
satellite observations. The atmospheric CO2 distribution in East Asia
during 2012 was simulated using a regional chemical transport model
(RAMS-CMAQ) and compared with both CO2 column density (XCO2) from the
Gases Observing SATellite (GOSAT) and CO2 concentrations from the World
Data Centre for Greenhouse Gases (WDCGG). The results indicate that
simulated XCO2 is generally lower than GOSAT XCO2 by 1.19 ppm on
average, and their monthly differences vary from 0.05 to 2.84 ppm, with
the corresponding correlation coefficients ranging between 0.1 and 0.67.
CMAQ simulations are good to capture the CO2 variation as ground-based
observations, and their correlation coefficients are from 0.62 to 0.93,
but the average value of CMAQ simulation is 2.4 ppm higher than
ground-based observation. Thus, we inferred that the GOSAT retrievals
may overestimate XCO2, which is consistent with the validation of GOSAT
XCO2 using Total Carbon Column Observing Network measurements. The
near-surface CO2 concentration was obviously overestimated in GOSAT
XCO2. Compared with the relatively small difference between CMAQ and
GOSAT XCO2, the large difference in CO2 near surface or their vertical
profiles indicates more improvements are needed to reduce the
uncertainties in both satellite observations and model simulations. (C)
2017 Elsevier Ltd. All rights reserved.
BibTeX:
@article{li17a,
  author = {Li, Rong and Zhang, Meigen and Chen, Liangfu and Kou, Xingxia and Skorokhod, Andrei},
  title = {CMAQ simulation of atmospheric CO2 concentration in East Asia: Comparison with GOSAT observations and ground measurements},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2017},
  volume = {160},
  pages = {176--185},
  doi = {10.1016/j.atmosenv.2017.03.056}
}
Liang M-C, Mahata S, Laskar AH and Bhattacharya SK ({2017}), "Spatiotemporal Variability of Oxygen Isotope Anomaly in near Surface Air CO2 over Urban, Semi-Urban and Ocean Areas in and around Taiwan", AEROSOL AND AIR QUALITY RESEARCH., MAR, {2017}. Vol. {17}({3}), pp. 706-720.
Abstract: The most commonly used tracers to probe the atmospheric and
biogeochemical cycles of CO2 are (OCO)-O-16-C-12-O-16,
(OCO)-O-16-C-13-O-16, and (OCO)-O-16-C-12-O-18. Considering the number
and diversity of sources and sinks affecting CO2, these tracers are not
always sufficient to constrain the fluxes of CO2 between the atmosphere
and biosphere/hydrosphere. In this context, (OCO)-O-16-C-12-O-17 species
was introduced but has rarely been used due to difficulties associated
with its accurate measurement in natural samples. This tracer, expressed
as an abundance anomaly in O-17, defined by Delta O-17 = ln(1 + delta
O-17) - 0.516 x ln(1 + delta O-18) can independently constrain the
fluxes associated with the terrestrial processes. The advantage of
utilizing Delta O-17 over delta O-18 alone lies on the sensitivity of
the former to the rates of biogeochemical processes involving multiple
water reservoirs with spatial and temporal isotopic heterogeneities. To
employ all the three oxygen isotopes for estimating fluxes of CO2,
sources and processes affecting their partitioning have to be identified
and quantified. Here, we measured Delta O-17 values in near surface
atmospheric CO2 from Taiwan in urban and semi-urban areas and over the
South China Sea. Strong spatiotemporal variation was seen, with an
average Delta O-17 value of 0.332% and a mean variation of 0.043br> (relative to V-SMOW; 1-sigma standard deviation for a total of 140
samples). The large variation reflects combinations of distinct air
masses carrying CO2 from sources having different Delta O-17 values:
negative from combustion emissions, positive from the stratosphere, and
a positive water-CO2 equilibration value from isotope exchange with
leaf/soil/ocean waters. We observed that the variation of the semi-urban
Delta O-17 values is largely affected by local biogeochemistry and
stratospheric intrusion with only minor influence from anthropogenic
emissions. This is the first oxygen anomaly study for near surface CO2
covering diverse source characteristics and has enormous potential in
air CO2 source identification and constraining the global carbon budget.
BibTeX:
@article{liang17a,
  author = {Liang, Mao-Chang and Mahata, Sasadhar and Laskar, Amzad H. and Bhattacharya, Sourendra K.},
  title = {Spatiotemporal Variability of Oxygen Isotope Anomaly in near Surface Air CO2 over Urban, Semi-Urban and Ocean Areas in and around Taiwan},
  journal = {AEROSOL AND AIR QUALITY RESEARCH},
  year = {2017},
  volume = {17},
  number = {3},
  pages = {706--720},
  doi = {10.4209/aaqr.2016.04.0171}
}
Lin JC, Mallia DV, Wu D and Stephens BB ({2017}), "How can mountaintop CO2 observations be used to constrain regional carbon fluxes?", ATMOSPHERIC CHEMISTRY AND PHYSICS., MAY 3, {2017}. Vol. {17}({9}), pp. 5561-5581.
Abstract: Despite the need for researchers to understand terrestrial biospheric
carbon fluxes to account for carbon cycle feedbacks and predict future
CO2 concentrations, knowledge of these fluxes at the regional scale
remains poor. This is particularly true in mountainous areas, where
complex meteorology and lack of observations lead to large uncertainties
in carbon fluxes. Yet mountainous regions are often where significant
forest cover and biomass are found - i.e., areas that have the potential
to serve as carbon sinks. As CO2 observations are carried out in
mountainous areas, it is imperative that they are properly interpreted
to yield information about carbon fluxes. In this paper, we present CO2
observations at three sites in the mountains of the western US, along
with atmospheric simulations that attempt to extract information about
biospheric carbon fluxes from the CO2 observations, with emphasis on the
observed and simulated diurnal cycles of CO2. We show that atmospheric
models can systematically simulate the wrong diurnal cycle and
significantly misinterpret the CO2 observations, due to erroneous
atmospheric flows as a result of terrain that is misrepresented in the
model. This problem depends on the selected vertical level in the model
and is exacerbated as the spatial resolution is degraded, and our
results indicate that a fine grid spacing of similar to 4 km or less may
be needed to simulate a realistic diurnal cycle of CO2 for sites on top
of the steep mountains examined here in the American Rockies. In the
absence of higher resolution models, we recommend coarse-scale models to
focus on assimilating afternoon CO2 observations on mountaintop sites
over the continent to avoid misrepresentations of nocturnal transport
and influence.
BibTeX:
@article{lin17a,
  author = {Lin, John C. and Mallia, Derek V. and Wu, Dien and Stephens, Britton B.},
  title = {How can mountaintop CO2 observations be used to constrain regional carbon fluxes?},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {9},
  pages = {5561--5581},
  doi = {10.5194/acp-17-5561-2017}
}
Lindqvist H, O'Dell CW, Basu S, Boesch H, Chevallier F, Deutscher N, Feng L, Fisher B, Hase F, Inoue M, Kivi R, Morino I, Palmer PI, Parker R, Schneider M, Sussmann R and Yoshida Y ({2015}), "Does GOSAT capture the true seasonal cycle of carbon dioxide?", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({22}), pp. 13023-13040.
Abstract: The seasonal cycle accounts for a dominant mode of total column CO2
(XCO2) annual variability and is connected to CO2 uptake and release; it
thus represents an important quantity to test the accuracy of the
measurements from space. We quantitatively evaluate the XCO2 seasonal
cycle of the Greenhouse Gases Observing Satellite (GOSAT) observations
from the Atmospheric CO2 Observations from Space (ACOS) retrieval system
and compare average regional seasonal cycle features to those directly
measured by the Total Carbon Column Observing Network (TCCON). We
analyse the mean seasonal cycle amplitude, dates of maximum and minimum
XCO2, as well as the regional growth rates in XCO2 through the fitted
trend over several years. We find that GOSAT/ACOS captures the seasonal
cycle amplitude within 1.0 ppm accuracy compared to TCCON, except in
Europe, where the difference exceeds 1.0 ppm at two sites, and the
amplitude captured by GOSAT/ACOS is generally shallower compared to
TCCON. This bias over Europe is not as large for the other GOSAT
retrieval algorithms (NIES v02.21, RemoTeC v2.35, UoL v5.1, and NIES
PPDF-S v.02.11), al-though they have significant biases at other sites.
We find that the ACOS bias correction partially explains the shallow
amplitude over Europe. The impact of the co-location method and aerosol
changes in the ACOS algorithm were also tested and found to be few
tenths of a ppm and mostly non-systematic. We find generally good
agreement in the date of minimum XCO2 between ACOS and TCCON, but ACOS
generally infers a date of maximum XCO2 2-3 weeks later than TCCON. We
further analyse the latitudinal dependence of the seasonal cycle
amplitude throughout the Northern Hemisphere and compare the dependence
to that predicted by current optimized models that assimilate in situ
measurements of CO2. In the zonal averages, models are consistent with
the GOSAT amplitude to within 1.4 ppm, depending on the model and
latitude. We also show that the seasonal cycle of XCO2 depends on
longitude especially at the mid-latitudes: the amplitude of GOSAT XCO2
doubles from western USA to East Asia at 45-50 degrees N, which is only
partially shown by the models. In general, we find that model-to-model
differences can be larger than GOSAT-to-model differences. These results
suggest that GOSAT/ACOS retrievals of the XCO2 seasonal cycle may be
sufficiently accurate to evaluate land surface models in regions with
significant discrepancies between the models.
BibTeX:
@article{lindqvist15a,
  author = {Lindqvist, H. and O'Dell, C. W. and Basu, S. and Boesch, H. and Chevallier, F. and Deutscher, N. and Feng, L. and Fisher, B. and Hase, F. and Inoue, M. and Kivi, R. and Morino, I. and Palmer, P. I. and Parker, R. and Schneider, M. and Sussmann, R. and Yoshida, Y.},
  title = {Does GOSAT capture the true seasonal cycle of carbon dioxide?},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {22},
  pages = {13023--13040},
  doi = {10.5194/acp-15-13023-2015}
}
Liu J, Fung I, Kalnay E, Kang J-S, Olsen ET and Chen L ({2012}), "Simultaneous assimilation of AIRS Xco(2) and meteorological observations in a carbon climate model with an ensemble Kalman filter", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 9, {2012}. Vol. {117}
Abstract: This study is our first step toward the generation of 6 hourly 3-D CO2
fields that can be used to validate CO2 forecast models by combining CO2
observations from multiple sources using ensemble Kalman filtering. We
discuss a procedure to assimilate Atmospheric Infrared Sounder (AIRS)
column-averaged dry-air mole fraction of CO2 (Xco(2)) in conjunction
with meteorological observations with the coupled Local Ensemble
Transform Kalman Filter (LETKF)-Community Atmospheric Model version 3.5.
We examine the impact of assimilating AIRS Xco(2) observations on CO2
fields by comparing the results from the AIRS-run, which assimilates
both AIRS Xco(2) and meteorological observations, to those from the
meteor-run, which only assimilates meteorological observations. We find
that assimilating AIRS Xco(2) results in a surface CO2 seasonal cycle
and the N-S surface gradient closer to the observations. When taking
account of the CO2 uncertainty estimation from the LETKF, the CO2
analysis brackets the observed seasonal cycle. Verification against
independent aircraft observations shows that assimilating AIRS Xco(2)
improves the accuracy of the CO2 vertical profiles by about 0.5-2 ppm
depending on location and altitude. The results show that the CO2
analysis ensemble spread at AIRS Xco(2) space is between 0.5 and 2 ppm,
and the CO2 analysis ensemble spread around the peak level of the
averaging kernels is between 1 and 2 ppm. This uncertainty estimation is
consistent with the magnitude of the CO2 analysis error verified against
AIRS Xco(2) observations and the independent aircraft CO2 vertical
profiles.
BibTeX:
@article{liu12a,
  author = {Liu, Junjie and Fung, Inez and Kalnay, Eugenia and Kang, Ji-Sun and Olsen, Edward T. and Chen, Luke},
  title = {Simultaneous assimilation of AIRS Xco(2) and meteorological observations in a carbon climate model with an ensemble Kalman filter},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2011JD016642}
}
Liu Z, Bambha RP, Pinto JP, Zeng T, Boylan J, Huang M, Lei H, Zhao C, Liu S, Mao J, Schwalm CR, Shi X, Wei Y and Michelsen HA ({2014}), "Toward verifying fossil fuel CO2 emissions with the CMAQ model: Motivation, model description and initial simulation", JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION., APR 3, {2014}. Vol. {64}({4}), pp. 419-435.
Abstract: Motivated by the question of whether and how a state-of-the-art regional
chemical transport model (CTM) can facilitate characterization of CO2
spatiotemporal variability and verify CO2 fossil-fuel emissions, we for
the first time applied the Community Multiscale Air Quality (CMAQ) model
to simulate CO2. This paper presents methods, input data, and initial
results for CO2 simulation using CMAQ over the contiguous United States
in October 2007. Modeling experiments have been performed to understand
the roles of fossil-fuel emissions, biosphere-atmosphere exchange, and
meteorology in regulating the spatial distribution of CO2 near the
surface over the contiguous United States. Three sets of net ecosystem
exchange (NEE) fluxes were used as input to assess the impact of
uncertainty of NEE on CO2 concentrations simulated by CMAQ.
Observational data from six tall tower sites across the country were
used to evaluate model performance. In particular, at the Boulder
Atmospheric Observatory (BAO), a tall tower site that receives urban
emissions from Denver, CO, the CMAQ model using hourly varying,
high-resolution CO2 fossil-fuel emissions from the Vulcan inventory and
CarbonTracker optimized NEE reproduced the observed diurnal profile of
CO2 reasonably well but with a low bias in the early morning. The
spatial distribution of CO2 was found to correlate with NOx, SO2, and
CO, because of their similar fossil-fuel emission sources and common
transport processes. These initial results from CMAQ demonstrate the
potential of using a regional CTM to help interpret CO2 observations and
understand CO2 variability in space and time. The ability to simulate a
full suite of air pollutants in CMAQ will also facilitate investigations
of their use as tracers for CO2 source attribution. This work serves as
a proof of concept and the foundation for more comprehensive
examinations of CO2 spatiotemporal variability and various uncertainties
in the future.
Implications:
Atmospheric CO2 has long been modeled and studied on continental to
global scales to understand the global carbon cycle. This work
demonstrates the potential of modeling and studying CO2 variability at
fine spatiotemporal scales with CMAQ, which has been applied
extensively, to study traditionally regulated air pollutants. The
abundant observational records of these air pollutants and successful
experience in studying and reducing their emissions may be useful for
verifying CO2 emissions. Although there remains much more to further
investigate, this work opens up a discussion on whether and how to study
CO2 as an air pollutant.
BibTeX:
@article{liu14a,
  author = {Liu, Zhen and Bambha, Ray P. and Pinto, Joseph P. and Zeng, Tao and Boylan, Jim and Huang, Maoyi and Lei, Huimin and Zhao, Chun and Liu, Shishi and Mao, Jiafu and Schwalm, Christopher R. and Shi, Xiaoying and Wei, Yaxing and Michelsen, Hope A.},
  title = {Toward verifying fossil fuel CO2 emissions with the CMAQ model: Motivation, model description and initial simulation},
  journal = {JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION},
  year = {2014},
  volume = {64},
  number = {4},
  pages = {419--435},
  doi = {10.1080/10962247.2013.816642}
}
Liu S, Zhuang Q, He Y, Noormets A, Chen J and Gu L ({2016}), "Evaluating atmospheric CO2 effects on gross primary productivity and net ecosystem exchanges of terrestrial ecosystems in the conterminous United States using the AmeriFlux data and an artificial neural network approach", AGRICULTURAL AND FOREST METEOROLOGY., APR 15, {2016}. Vol. {220}, pp. 38-49.
Abstract: Quantitative understanding of regional gross primary productivity (GPP)
and net ecosystem exchanges (NEE) and their responses to environmental
changes are critical to quantifying the feedbacks of ecosystems to the
global climate system. Numerous studies have used the eddy flux data to
upscale the eddy covariance derived carbon fluxes from stand scales to
regional and global scales. However, few studies incorporated
atmospheric carbon dioxide (CO2) concentrations into those
extrapolations. Here, we consider the effect of atmospheric CO2 using an
artificial neural network (ANN) approach to upscale the AmeriFlux tower
of NEE and the derived GPP to the conterminous United States. Two ANN
models incorporating remote sensing variables at an 8-day time step were
developed. One included CO2 as an explanatory variable and the other did
not. The models were first trained, validated using eddy flux data, and
then extrapolated to the region at a 0.05 degrees x 0.05 degrees
(latitude x longitude) resolution from 2001 to 2006. We found that both
models performed well in simulating site-level carbon fluxes. The
spatially averaged annual GPP with and without considering the
atmospheric CO2 were 789 and 788 g Cm-2 yr(-1), respectively (for NEE,
the values were 112 and 109 g Cm-2 yr(-1), respectively). Model
predictions were comparable with previous published results and MODIS
GPP products. However, the difference in GPP between the two models
exhibited a great spatial and seasonal variability, with an annual
difference of 200 g Cm-2 yr(-1). Further analysis suggested that air
temperature played an important role in determining the atmospheric CO2
effects on carbon fluxes. In addition, the simulation that did not
consider atmospheric CO2 failed to detect ecosystem responses to
droughts in part of the US in 2006. The study suggests that the
spatially and temporally varied atmospheric CO2 concentrations should be
factored into carbon quantification when scaling eddy flux data to a
region. (C) 2016 Elsevier B.V. All rights reserved.
BibTeX:
@article{liu16a,
  author = {Liu, Shaoqing and Zhuang, Qianlai and He, Yujie and Noormets, Asko and Chen, Jiquan and Gu, Lianhong},
  title = {Evaluating atmospheric CO2 effects on gross primary productivity and net ecosystem exchanges of terrestrial ecosystems in the conterminous United States using the AmeriFlux data and an artificial neural network approach},
  journal = {AGRICULTURAL AND FOREST METEOROLOGY},
  year = {2016},
  volume = {220},
  pages = {38--49},
  doi = {10.1016/j.agrformet.2016.01.007}
}
Liu M, Lei L, Liu D and Zeng Z-C ({2016}), "Geostatistical Analysis of CH4 Columns over Monsoon Asia Using Five Years of GOSAT Observations", REMOTE SENSING., MAY, {2016}. Vol. {8}({5})
Abstract: The aim of this study is to evaluate the Greenhouse gases Observation
SATellite (GOSAT) column-averaged CH4 dry air mole fraction (XCH4) data
by using geostatistical analysis and conducting comparisons with model
simulations and surface emissions. Firstly, we propose the use of a
data-driven mapping approach based on spatio-temporal geostatistics to
generate a regular and gridded mapping dataset of XCH4 over Monsoon Asia
using five years of XCH4 retrievals by GOSAT from June 2009 to May 2014.
The prediction accuracy of the mapping approach is assessed by using
cross-validation, which results in a significantly high correlation of
0.91 and a small mean absolute prediction error of 8.77 ppb between the
observed dataset and the prediction dataset. Secondly, with the mapping
data, we investigate the spatial and temporal variations of XCH4 over
Monsoon Asia and compare the results with previous studies on ground and
other satellite observations. Thirdly, we compare the mapping XCH4 with
model simulations from CarbonTracker-CH4 and find their spatial patterns
very consistent, but GOSAT observations are more able to capture the
local variability of XCH4. Finally, by correlating the mapping data with
surface emission inventory, we find the geographical distribution of
high CH4 values correspond well with strong emissions as indicated in
the inventory map. Over the five-year period, the two datasets show a
significant high correlation coefficient (0.80), indicating the dominant
role of surface emissions in determining the distribution of XCH4
concentration in this region and suggesting a promising statistical way
of constraining surface CH4 sources and sinks, which is simple and easy
to implement using satellite observations over a long term period.
BibTeX:
@article{liu16b,
  author = {Liu, Min and Lei, Liping and Liu, Da and Zeng, Zhao-Cheng},
  title = {Geostatistical Analysis of CH4 Columns over Monsoon Asia Using Five Years of GOSAT Observations},
  journal = {REMOTE SENSING},
  year = {2016},
  volume = {8},
  number = {5},
  doi = {10.3390/rs8050361}
}
Liu J, Bowman KW and Lee M ({2016}), "Comparison between the Local Ensemble Transform Kalman Filter (LETKF) and 4D-Var in atmospheric CO2 flux inversion with the Goddard Earth Observing System-Chem model and the observation impact diagnostics from the LETKF", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 16, {2016}. Vol. {121}({21}), pp. 13066-13087.
BibTeX:
@article{liu16c,
  author = {Liu, Junjie and Bowman, Kevin W. and Lee, Meemong},
  title = {Comparison between the Local Ensemble Transform Kalman Filter (LETKF) and 4D-Var in atmospheric CO2 flux inversion with the Goddard Earth Observing System-Chem model and the observation impact diagnostics from the LETKF},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2016},
  volume = {121},
  number = {21},
  pages = {13066--13087},
  doi = {10.1002/2016JD025100}
}
Liu S (2016), "Quantifying terrestrial ecosystem carbon dynamics with mechanistically-based biogeochemistry models and in situ and remotely sensed data". Thesis at: Purdue University.
BibTeX:
@phdthesis{liu16d,
  author = {Liu, Shaoqing},
  title = {Quantifying terrestrial ecosystem carbon dynamics with mechanistically-based biogeochemistry models and in situ and remotely sensed data},
  school = {Purdue University},
  year = {2016},
  url = {http://search.proquest.com/openview/6c838317951d8ea5b5e0409c75ea25e9/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Liu S, Zhuang Q, Chen M and Gu L (2016), "Quantifying spatially and temporally explicit CO2 fertilization effects on global terrestrial ecosystem carbon dynamics", Ecosphere. Vol. 7(7)
BibTeX:
@article{liu16e,
  author = {Liu, Shaoqing and Zhuang, Qianlai and Chen, Min and Gu, Lianhong},
  title = {Quantifying spatially and temporally explicit CO2 fertilization effects on global terrestrial ecosystem carbon dynamics},
  journal = {Ecosphere},
  year = {2016},
  volume = {7},
  number = {7},
  doi = {10.1002/ecs2.1391/full}
}
Liu Z, Ballantyne AP, Poulter B, Anderegg WRL, Li W, Bastos A and Ciais P ({2018}), "Precipitation thresholds regulate net carbon exchange at the continental scale", NATURE COMMUNICATIONS., SEP 5, {2018}. Vol. {9}
Abstract: Understanding the sensitivity of ecosystem production and respiration to
climate change is critical for predicting terrestrial carbon dynamics.
Here we show that the primary control on the inter-annual variability of
net ecosystem carbon exchange switches from production to respiration at
a precipitation threshold between 750 and 950 mm yr(-1) in the
contiguous United States. This precipitation threshold is evident across
multiple datasets and scales of observation indicating that it is a
robust result and provides a new scaling relationship between climate
and carbon dynamics. However, this empirical precipitation threshold is
not captured by dynamic global vegetation models, which tend to
overestimate the sensitivity of production and underestimate the
sensitivity of respiration to water availability in more mesic regions.
Our results suggest that the short-term carbon balance of ecosystems may
be more sensitive to respiration losses than previously thought and that
model simulations may underestimate the positive carbon-climate
feedbacks associated with respiration.
BibTeX:
@article{liu18a,
  author = {Liu, Zhihua and Ballantyne, Ashley P. and Poulter, Benjamin and Anderegg, William R. L. and Li, Wei and Bastos, Ana and Ciais, Philippe},
  title = {Precipitation thresholds regulate net carbon exchange at the continental scale},
  journal = {NATURE COMMUNICATIONS},
  year = {2018},
  volume = {9},
  doi = {{10.1038/s41467-018-05948-1}}
}
Liu J, Bowman K, Parazoo NC, Bloom AA, Wunch D, Jiang Z, Gurney KR and Schimel D ({2018}), "Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations", ENVIRONMENTAL RESEARCH LETTERS., SEP, {2018}. Vol. {13}({9})
Abstract: With projections of increasing drought in the future, understanding how
the natural carbon cycle responds to drought events is needed to predict
the fate of the land carbon sink and future atmospheric CO2
concentrations and climate. We quantified the impacts of the 2011 and
2012 droughts on terrestrial ecosystem carbon uptake anomalies over the
contiguous US (CONUS) relative to non-drought years during 2010-2015
using satellite observations and the carbon monitoring system-flux
inversion modeling framework. Soilmoisture and temperature anomalies are
good predictors of gross primary production anomalies (R-2 > 0.6) in
summer but less so for net biosphere production (NBP) anomalies,
reflecting different respiration responses. We showed that regional
responses combine in complicated ways to produce the observed CONUS
responses. Because of the compensating effect of the carbonflux
anomalies between northern and southern CONUS in 2011 and between spring
and summer in 2012, the annual NBP decreased by 0.10 +/- 0.16 GtC in
2011, and increased by 0.10 +/- 0.16 GtC in 2012 over CONUS, consistent
with previous reported results. Over the 2011 and 2012 drought-impacted
regions, the reductions in NBP were similar to 40% of the regional
annual fossil fuel emissions, underscoring the importance of quantifying
natural carbon flux variability as part of an overall observing
strategy. The NBP reductions over the 2011 and 2012 CONUS
drought-impacted region were opposite to the global atmospheric CO2
growth rate anomaly, implying that global atmospheric CO2 growth rate is
an offsetting effect between enhanced uptake and emission, and enhancing
the understanding of regional carbon-cycle climate relationship is
necessary to improve the projections of future climate.
BibTeX:
@article{liu18b,
  author = {Liu, Junjie and Bowman, Kevin and Parazoo, Nicholas C. and Bloom, A. Anthony and Wunch, Debra and Jiang, Zhe and Gurney, Kevin R. and Schimel, Dave},
  title = {Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations},
  journal = {ENVIRONMENTAL RESEARCH LETTERS},
  year = {2018},
  volume = {13},
  number = {9},
  doi = {{10.1088/1748-9326/aad5ef}}
}
Liu Y, Yue T, Zhang L, Zhao N, Zhao M and Liu Y ({2018}), "Simulation and analysis of XCO2 in North China based on high accuracy surface modeling", ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH., SEP, {2018}. Vol. {25}({27, SI}), pp. {27378-27392}.
Abstract: As an important cause of global warming, CO2 concentrations and their
changes have aroused worldwide concern. Establishing explicit
understanding of the spatial and temporal distributions of CO2
concentrations at regional scale is a crucial technical problem for
climate change research. High accuracy surface modeling (HASM) is
employed in this paper using the output of the CO2 concentrations from
weather research and forecasting-chemistry (WRF-CHEM) as the driving
fields, and the greenhouse gases observing satellite (GOSAT) retrieval
XCO2 data as the accuracy control conditions to obtain high accuracy
XCO2 fields. WRF-CHEM is an atmospheric chemical transport model
designed for regional studies of CO2 concentrations. Verified by ground-
and space-based observations, WRF-CHEM has a limited ability to simulate
the conditions of CO2 concentrations. After conducting HASM, we obtain a
higher accuracy distribution of the CO2 in North China than those
calculated using the classical Kriging and inverse distance weighted
(IDW) interpolation methods, which were often used in past studies. The
cross-validation also shows that the averaging mean absolute error (MAE)
of the results from HASM is 1.12 ppmv, and the averaging root mean
square error (RMSE) is 1.41 ppmv, both of which are lower than those of
the Kriging and IDW methods. This study also analyses the space-time
distributions and variations of the XCO2 from the HASM results. This
analysis shows that in February and March, there was the high value zone
in the southern region of study area relating to heating in the winter
and the dense population. The XCO2 concentration decreased by the end of
the heating period and during the growing period of April and May, and
only some relatively high value zones continued to exist.
BibTeX:
@article{liu18c,
  author = {Liu, Yu and Yue, Tianxiang and Zhang, Lili and Zhao, Na and Zhao, Miaomiao and Liu, Yi},
  title = {Simulation and analysis of XCO2 in North China based on high accuracy surface modeling},
  journal = {ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH},
  year = {2018},
  volume = {25},
  number = {27, SI},
  pages = {27378-27392},
  doi = {{10.1007/s11356-018-2683-x}}
}
Lokupitiya RS, Zupanski D, Denning AS, Kawa SR, Gurney KR and Zupanski M ({2008}), "Estimation of global CO2 fluxes at regional scale using the maximum likelihood ensemble filter", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 22, {2008}. Vol. {113}({D20})
Abstract: We use an ensemble-based data assimilation method, known as the maximum
likelihood ensemble filter (MLEF), which has been coupled with a global
atmospheric transport model to estimate slowly varying biases of carbon
surface fluxes. Carbon fluxes for this test consist of hourly gross
primary production and ecosystem, respiration over land, and air-sea gas
exchange. Persistent multiplicative biases intended to represent
incorrectly simulated biogeochemical or land-management processes such
as stand age, soil fertility, or coarse woody debris were estimated for
1 year at 10 degrees longitude by 6 degrees latitude spatial resolution
and with an 8-week time window. We tested the model using a pseudodata
experiment with an existing observation network that includes flasks,
aircraft profiles, and continuous measurements. Because of the
underconstrained nature of the problem, strong covariance smoothing was
applied in the first data assimilation cycle, and localization schemes
have been introduced. Error covariance was propagated in subsequent
cycles. The coupled model satisfactorily recovered the land biases in
densely observed areas. Ocean biases, however, were poorly constrained
by the atmospheric observations. Unlike in batch mode inversions, the
MLEF has a capability of assimilating large observation vectors and
hence is suitable for assimilating hourly continuous observations and
satellite observations in the future. Uncertainty was reduced further in
our pseudodata experiment than by previous batch methods because of the
ability to assimilate a large observation vector. Propagation of spatial
covariance and dynamic localization avoid the need for prescribed
spatial patterns of error covariance centered at observation sites as in
previous grid-scale methods.
BibTeX:
@article{lokupitiya08a,
  author = {Lokupitiya, R. S. and Zupanski, D. and Denning, A. S. and Kawa, S. R. and Gurney, K. R. and Zupanski, M.},
  title = {Estimation of global CO2 fluxes at regional scale using the maximum likelihood ensemble filter},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2008},
  volume = {113},
  number = {D20},
  doi = {10.1029/2007JD009679}
}
Luan T, LingXi Z, ShuangXi F, Yao B, Wang H and Liu Z (2014), "Atmospheric CO2 Data Filtering Method and Characteristics of the Molar Fractions at the Longfengshan WMO/GAW Regional Station in China", Environmental Science. Vol. 35(8)
BibTeX:
@article{luan14a,
  author = {Luan, Tian and Zhou LingXi and Fang ShuangXi and Yao, Bo and Wang, Hongyang and Liu, Zhao},
  title = {Atmospheric CO2 Data Filtering Method and Characteristics of the Molar Fractions at the Longfengshan WMO/GAW Regional Station in China},
  journal = {Environmental Science},
  year = {2014},
  volume = {35},
  number = {8},
  url = {http://www.hjkx.ac.cn/hjkx/ch/html/20140804.htm}
}
Lukyanov AN, Gan'shin AV, Zhuravlev RV, Maksyutov SS and Varlagin AV ({2015}), "Global Lagrangian Atmospheric Dispersion Model", IZVESTIYA ATMOSPHERIC AND OCEANIC PHYSICS., SEP, {2015}. Vol. {51}({5}), pp. 505-511.
Abstract: The Global Lagrangian Atmospheric Dispersion Model (GLADIM) is
described. GLADIM is based on the global trajectory model, which had
been developed earlier and uses fields of weather parameters from
different atmospheric reanalysis centers for calculations of
trajectories of air mass that include trace gases. GLADIM includes the
parameterization of turbulent diffusion and allows the forward
calculation of concentrations of atmospheric tracers at nodes of a
global regular grid when a source is specified. Thus, GLADIM can be used
for the forward simulation of pollutant propagation (volcanic ash,
radionuclides, and so on). Working in the reverse direction, GLADIM
allows the detection of remote sources that mainly contribute to the
tracer concentration at an observation point. This property of
Lagrangian models is widely used for data analysis and the reverse
modeling of emission sources of a pollutant specified. In this work we
describe the model and some results of its validation through a
comparison with results of a similar model and observation data.
BibTeX:
@article{lukyanov15a,
  author = {Lukyanov, A. N. and Gan'shin, A. V. and Zhuravlev, R. V. and Maksyutov, Sh. Sh. and Varlagin, A. V.},
  title = {Global Lagrangian Atmospheric Dispersion Model},
  journal = {IZVESTIYA ATMOSPHERIC AND OCEANIC PHYSICS},
  year = {2015},
  volume = {51},
  number = {5},
  pages = {505--511},
  doi = {10.1134/S0001433815040076}
}
Luus KA and Lin JC ({2015}), "The Polar Vegetation Photosynthesis and Respiration Model: a parsimonious, satellite-data-driven model of high-latitude CO2 exchange", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {8}({8}), pp. 2655-2674.
Abstract: We introduce the Polar Vegetation Photosynthesis and Respiration Model
(PolarVPRM), a remote-sensing-based approach for generating accurate,
high-resolution (>= 1 km(2), 3 hourly) estimates of net ecosystem CO2
exchange (NEE). PolarVPRM simulates NEE using polar-specific vegetation
classes, and by representing high-latitude influences on NEE, such as
the influence of soil temperature on subnivean respiration. We present a
description, validation and error analysis (first-order Taylor
expansion) of PolarVPRM, followed by an examination of per-pixel trends
(2001-2012) in model output for the North American terrestrial region
north of 55 degrees N. PolarVPRM was validated against eddy covariance
(EC) observations from nine North American sites, of which three were
used in model calibration. Comparisons of EC NEE to NEE from three
models indicated that PolarVPRM displayed similar or better statistical
agreement with eddy covariance observations than existing models showed.
Trend analysis (2001-2012) indicated that warming air temperatures and
drought stress in forests increased growing season rates of respiration,
and decreased rates of net carbon uptake by vegetation when air
temperatures exceeded optimal temperatures for photosynthesis.
Concurrent increases in growing season length at Arctic tundra sites
allowed for increases in photosynthetic uptake over time by tundra
vegetation. PolarVPRM estimated that the North American high-latitude
region changed from a carbon source (2001-2004) to a carbon sink
(2005-2010) to again a source (2011-2012) in response to changing
environmental conditions.
BibTeX:
@article{luus15a,
  author = {Luus, K. A. and Lin, J. C.},
  title = {The Polar Vegetation Photosynthesis and Respiration Model: a parsimonious, satellite-data-driven model of high-latitude CO2 exchange},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2015},
  volume = {8},
  number = {8},
  pages = {2655--2674},
  doi = {10.5194/gmd-8-2655-2015}
}
Mabuchi K, Takagi H and Maksyutov S ({2016}), "Relationships between CO2 Flux Estimated by Inverse Analysis and Land Surface Elements in South America and Africa", JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN. Vol. {94}({5}), pp. 415-430.
Abstract: Inverse analysis estimates the regional flux of greenhouse gases between
the earth's surface and atmosphere using observed atmospheric
concentration data that include satellite data. In particular, this
method is effective in estimating the flux in regions where
observational flux data are limited. However, inverse analysis is
basically a mathematical optimization method. Therefore, confirmation of
the causal validity of the spatial and temporal changes in the estimated
flux is necessary. One confirmation method is validation of the
relationship with physical and biological observation data (analysis
data) of confirmed accuracy. In this study, the features and validity of
changes in the carbon dioxide (CO2) flux estimated by inverse analysis
were verified via interrelation analysis, with changes in precipitation,
short-wave radiation, surface temperature, and Normalized Difference
Vegetation Index (NDVI) in regions of South America and Africa where CO2
flux observation data are limited. Sufficient accuracy of the land
surface elements is required for the analysis results to confirm the CO2
flux estimated by inverse analysis. An examination of the correlation of
anomalies showed consistent relationships among the precipitation,
short-wave radiation, surface temperature, and NDVI data used in this
study, which were independently created. The relationships between
change in the estimated CO2 flux and characteristic changes in the land
surface elements in South America and Africa were consistent for each
region. This study confirmed the physical and biological validity of the
changes in the CO2 flux estimated by inverse analysis. During the period
of this study, the NDVI anomaly was influential in South America and the
precipitation (soil wetness) anomaly was an essential factor in Africa
for the CO2 flux anomaly. The short-wave radiation anomaly was also
influential in both South America and Africa. The distinctive
relationships are more clearly detected in the results of inverse
analysis using both ground-based CO2 concentration data and the
Greenhouse gases Observing SATellite (GOSAT) data than in the results
using only ground-based CO2 concentration data. This demonstrates the
usefulness of GOSAT data in regions with limited atmospheric CO2
concentration data.
BibTeX:
@article{mabuchi16a,
  author = {Mabuchi, Kazuo and Takagi, Hiroshi and Maksyutov, Shamil},
  title = {Relationships between CO2 Flux Estimated by Inverse Analysis and Land Surface Elements in South America and Africa},
  journal = {JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN},
  year = {2016},
  volume = {94},
  number = {5},
  pages = {415--430},
  doi = {10.2151/jmsj.2016-021}
}
Macatangay R, Warneke T, Gerbig C, Koerner S, Ahmadov R, Heimann M and Notholt J ({2008}), "A framework for comparing remotely sensed and in-situ CO2 concentrations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {8}({9}), pp. 2555-2568.
Abstract: A framework has been developed that allows validating CO2 column
averaged volume mixing ratios (VMRs) retrieved from ground-based solar
absorption measurements using Fourier transform infrared spectrometry
(FTS) against measurements made in-situ (such as from aircrafts and tall
towers). Since in-situ measurements are done frequently and at high
accuracy on the global calibration scale, linking this scale with FTS
total column retrievals ultimately provides a calibration scale for
remote sensing. FTS, tower and aircraft data were analyzed from
measurements during the CarboEurope Regional Experiment Strategy (CERES)
from May to June 2005 in Biscarrosse, France. Carbon dioxide VMRs from
the MetAir Dimona aircraft, the TM3 global transport model and
Observations of the Middle Stratosphere (OMS) balloon based experiments
were combined and integrated to compare with the FTS measurements. The
comparison allows for calibrating the retrieved carbon dioxide VMRs from
the FTS. The Stochastic Time Inverted Lagrangian Transport (STILT) model
was then utilized to identify differences in surface influence regions
or footprints between the FTS and the aircraft CO2 concentrations.
Additionally, the STILT model was used to compare carbon dioxide
concentrations from a tall tower situated in close proximity to the FTS
station. The STILT model was then modified to produce column
concentrations of CO2 to facilitate comparison with the FTS data. These
comparisons were additionally verified by using the Weather Research and
Forecasting -; Vegetation Photosynthesis and Respiration Model
(WRF-VPRM). The differences between the model-tower and the model-FTS
were then used to calculate an effective bias of approximately -2.5 ppm
between the FTS and the tower. This bias is attributed to the scaling
factor used in the FTS CO2 data, which was to a large extent derived
from the aircraft measurements made within a 50 km distance from the FTS
station: spatial heterogeneity of carbon dioxide in the coastal area
caused a low bias in the FTS calibration. Using STILT for comparing
remotely sensed CO2 data with tower measurements of carbon dioxide and
quantifying this comparison by means of an effective bias, provided a
framework or a `transfer standard' that allowed validating the FTS
retrievals versus measurements made in-situ.
BibTeX:
@article{macatangay08a,
  author = {Macatangay, R. and Warneke, T. and Gerbig, C. and Koerner, S. and Ahmadov, R. and Heimann, M. and Notholt, J.},
  title = {A framework for comparing remotely sensed and in-situ CO2 concentrations},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2008},
  volume = {8},
  number = {9},
  pages = {2555--2568},
  doi = {10.5194/acp-8-2555-2008}
}
Maddy E, Barnet C, Goldberg M, Sweeney C and Liu X (2008), "CO2 retrievals from the Atmospheric Infrared Sounder: Methodology and validation", Journal of Geophysical Research: Atmospheres. Vol. 113(D11)
BibTeX:
@article{maddy08a,
  author = {Maddy, ES and Barnet, CD and Goldberg, M and Sweeney, C and Liu, X},
  title = {CO2 retrievals from the Atmospheric Infrared Sounder: Methodology and validation},
  journal = {Journal of Geophysical Research: Atmospheres},
  year = {2008},
  volume = {113},
  number = {D11},
  doi = {10.1029/2007JD009402/full}
}
Mahata S, Wang C-H, Bhattacharya SK and Liang M-C ({2016}), "Near Surface CO2 Triple Oxygen Isotope Composition", TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES., FEB, {2016}. Vol. {27}({1}), pp. 99-106.
Abstract: The isotopic composition of carbon dioxide in the atmosphere is a
powerful tool for constraining its sources and sinks. In particular, the
O-17 oxygen anomaly [Delta O-17 = 1000 x ln(1 + delta O-17/1000) -
0.516 x 1000 x ln(1 + delta O-18/1000)], with a value > 0.5 parts per
thousand produced in the middle atmosphere, provides an ideal tool for
probing the exchange of carbon dioxide between the biosphere/hydrosphere
and atmosphere. The biosphere/hydrosphere and anthropogenic emissions
give values <= 0.3 parts per thousand. Therefore, any anomaly in near
surface CO2 would reflect the balance between stratospheric input and
exchange with the aforementioned surface sources. We have analyzed Delta
O-17 values of CO2 separated from air samples collected in Taipei,
Taiwan, located in the western Pacific region. The obtained mean anomaly
is 0.42 +/- 0.14 parts per thousand (1-sigma standard deviation), in
good agreement with model prediction and a published decadal record.
Apart from typically used delta C-13 and delta O-18 values, the Delta
O-17 value could provide an additional tracer for constraining the
carbon cycle.
BibTeX:
@article{mahata16a,
  author = {Mahata, Sasadhar and Wang, Chung-Ho and Bhattacharya, Sourendra Kumar and Liang, Mao-Chang},
  title = {Near Surface CO2 Triple Oxygen Isotope Composition},
  journal = {TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES},
  year = {2016},
  volume = {27},
  number = {1},
  pages = {99--106},
  doi = {10.3319/TAO.2015.09.16.01(A)}
}
Mai B, An X, Deng X, Zhou L, Wang C, Huang J, Chen L and Yin S (2014), "Simulation analysis and verification of surface CO2 flux over Pearl River Delta, China", China Environmental Science. Vol. 34(8), pp. 1960-1971.
BibTeX:
@article{mai14a,
  author = {Mai, Boru and An, Xingqin and Deng, Xuejiao and Zhou, Lingxi and Wang, Chunlin and Huang, Jianping and Chen, Ling and Yin, Shuxian},
  title = {Simulation analysis and verification of surface CO2 flux over Pearl River Delta, China},
  journal = {China Environmental Science},
  year = {2014},
  volume = {34},
  number = {8},
  pages = {1960--1971},
  url = {http://manu36.magtech.com.cn/Jweb_zghjkx/CN/article/downloadArticleFile.do?attachType=PDF&id=13755}
}
麦博儒, 邓雪娇, 安兴琴, 周凌晞, 谭浩波, 李菲 and 李楠 (2014), "基于碳源汇模式系统 Carbon Tracker 的广东省近地层典型 CO2 过程模拟研究", 环境科学学报.
BibTeX:
@article{mai14b,
  author = {麦博儒 and 邓雪娇 and 安兴琴 and 周凌晞 and 谭浩波 and 李菲 and 李楠},
  title = {基于碳源汇模式系统 Carbon Tracker 的广东省近地层典型 CO2 过程模拟研究},
  journal = {环境科学学报},
  year = {2014},
  url = {http://www.cqvip.com/qk/91840x/201407/663141023.html}
}
Majkut JD (2014), "Variability and Trends in the Carbon Cycle". Thesis at: Princeton University.
BibTeX:
@phdthesis{majkut14a,
  author = {Majkut, Joseph Daniel},
  title = {Variability and Trends in the Carbon Cycle},
  school = {Princeton University},
  year = {2014},
  url = {http://search.proquest.com/openview/e90b562d689cf3a0ab70ffe5a30cd505/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Maki T, Ikegami M, Fujita T, Hirahara T, Yamada K, Mori K, Takeuchi A, Tsutsumi Y, Suda K and Conway TJ ({2010}), "New technique to analyse global distributions of CO2 concentrations and fluxes from non-processed observational data", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., NOV, {2010}. Vol. {62}({5, SI}), pp. 797-809.
Abstract: We have developed a new observational screening technique for inverse
model. This technique was applied to our transport models with
re-analysed meteorological data and the inverse model to estimate the
global distribution of CO2 concentrations and fluxes. During the 1990s,
we estimated a total CO2 uptake by the biosphere of 1.4-1.5 PgC yr-1 and
a total CO2 uptake by the oceans of 1.7-1.8 PgC yr-1. The uncertainty of
global CO2 flux estimation is about 0.3 PgC yr-1. We also obtained
monthly surface CO2 concentrations in the marine boundary layer to
precisions of 0.5-1.0 ppm. To utilize non-processed (statistical monthly
mean) observational data in our analysis, we developed a quality control
procedure for such observational data including a repetition of
inversion. This technique is suitable for other inversion setups.
Observational data by ships were placed into grids and used in our
analysis to add to the available data from fixed stations. The estimated
global distributions are updated and extended every year.
BibTeX:
@article{maki10a,
  author = {Maki, T. and Ikegami, M. and Fujita, T. and Hirahara, T. and Yamada, K. and Mori, K. and Takeuchi, A. and Tsutsumi, Y. and Suda, K. and Conway, T. J.},
  title = {New technique to analyse global distributions of CO2 concentrations and fluxes from non-processed observational data},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2010},
  volume = {62},
  number = {5, SI},
  pages = {797--809},
  doi = {10.1111/j.1600-0889.2010.00488.x}
}
Maksyutov S, Takagi H, Belikov DA, Saeki T, Zhuravlev R, Ganshin A, Lukyanov A, Yoshida Y, Oshchepkov S, Bril A, Saito M, Oda T, Valsala VK, Saito R, Andres RJ, Conway T, Tans P and Yokota T ({2012}), "Estimation of regional surface CO2 fluxes with GOSAT observations using two inverse modeling approaches", In REMOTE SENSING AND MODELING OF THE ATMOSPHERE, OCEANS, AND INTERACTIONS IV. Vol. {8529}
Abstract: Inverse estimation of surface CO2 fluxes is performed with atmospheric
transport model using ground-based and GOSAT observations. The
NIES-retrieved CO2 column mixing (X-CO2) and column averaging kernel are
provided by GOSAT Level 2 product v. 2.0 and PPDF-DOAS method. Monthly
mean CO2 fluxes for 64 regions are estimated together with a global mean
offset between GOSAT data and ground-based data. We used the fixed-lag
Kalman filter to infer monthly fluxes for 42 sub-continental terrestrial
regions and 22 oceanic basins. We estimate fluxes and compare results
obtained by two inverse modeling approaches. In basic approach adopted
in GOSAT Level 4 product v. 2.01, we use aggregation of the GOSAT
observations into monthly mean over 5x5 degree grids, fluxes are
estimated independently for each region, and NIES atmospheric transport
model is used for forward simulation. In the alternative method, the
model-observation misfit is estimated for each observation separately
and fluxes are spatially correlated using EOF analysis of the simulated
flux variability similar to geostatistical approach, while transport
simulation is enhanced by coupling with a Lagrangian transport model
Flexpart. Both methods use using the same set of prior fluxes and region
maps. Daily net ecosystem exchange (NEE) is predicted by the Vegetation
Integrative SImulator for Trace gases (VISIT) optimized to match
seasonal cycle of the atmospheric CO2. Monthly ocean-atmosphere CO2
fluxes are produced with an ocean pCO(2) data assimilation system.
Biomass burning fluxes were provided by the Global Fire Emissions
Database (GFED); and monthly fossil fuel CO2 emissions are estimated
with ODIAC inventory. The results of analyzing one year of the GOSAT
data suggest that when both GOSAT and ground-based data are used
together, fluxes in tropical and other remote regions with lower
associated uncertainties are obtained than in the analysis using only
ground-based data. With version 2.0 of L2 X-CO2 the fluxes appear
reasonable for many regions and seasons, however there is a need for
improving the L2 bias correction, data filtering and the inverse
modeling method to reduce estimated flux anomalies visible in some
areas. We also observe that application of spatial flux correlations
with EOF-based approach reduces flux anomalies.
BibTeX:
@inproceedings{maksyutov12a,
  author = {Maksyutov, Shamil and Takagi, Hiroshi and Belikov, Dmitry A. and Saeki, Tazu and Zhuravlev, Ruslan and Ganshin, Alexander and Lukyanov, Alexander and Yoshida, Yukio and Oshchepkov, Sergey and Bril, Andrey and Saito, Makoto and Oda, Tomohiro and Valsala, Vinu K. and Saito, Ryu and Andres, Robert J. and Conway, Thomas and Tans, Pieter and Yokota, Tatsuya},
  editor = {Kawamiya, M and Krishnamurti, TN and Maksyutov, S},
  title = {Estimation of regional surface CO2 fluxes with GOSAT observations using two inverse modeling approaches},
  booktitle = {REMOTE SENSING AND MODELING OF THE ATMOSPHERE, OCEANS, AND INTERACTIONS IV},
  year = {2012},
  volume = {8529},
  note = {Conference on Remote Sensing and Modeling of the Atmosphere, Oceans, and Interactions IV, Kyoto, JAPAN, OCT 31-NOV 01, 2012},
  doi = {10.1117/12.979664}
}
Maksyutov S, Takagi H, Valsala VK, Saito M, Oda T, Saeki T, Belikov DA, Saito R, Ito A, Yoshida Y, Morino I, Uchino O, Andres RJ and Yokota T ({2013}), "Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({18}), pp. 9351-9373.
Abstract: We present the application of a global carbon cycle modeling system to
the estimation of monthly regional CO2 fluxes from the column-averaged
mole fractions of CO2 (X-CO2) retrieved from spectral observations made
by the Greenhouse gases Observing SATellite (GOSAT). The regional flux
estimates are to be publicly disseminated as the GOSAT Level 4 data
product. The forward modeling components of the system include an
atmospheric tracer transport model, an anthropogenic emissions
inventory, a terrestrial biosphere exchange model, and an oceanic flux
model. The atmospheric tracer transport was simulated using isentropic
coordinates in the stratosphere and was tuned to reproduce the age of
air. We used a fossil fuel emission inventory based on large point
source data and observations of night-time lights. The terrestrial
biospheric model was optimized by fitting model parameters to observed
atmospheric CO2 seasonal cycle, net primary production data, and a
biomass distribution map. The oceanic surface pCO(2) distribution was
estimated with a 4-D variational data assimilation system based on
reanalyzed ocean currents. Monthly CO2 fluxes of 64 sub-continental
regions, between June 2009 and May 2010, were estimated from GOSAT FTS
SWIR Level 2 X-CO2 retrievals (ver. 02.00) gridded to 5 degrees x 5
degrees cells and averaged on a monthly basis and monthly-mean
GLOBALVIEW-CO2 data. Our result indicated that adding the GOSAT X-CO2
retrievals to the GLOBALVIEW data in the flux estimation brings changes
to fluxes of tropics and other remote regions where the surface-based
data are sparse. The uncertainties of these remote fluxes were reduced
by as much as 60% through such addition. Optimized fluxes estimated for
many of these regions, were brought closer to the prior fluxes by the
addition of the GOSAT retrievals. In most of the regions and seasons
considered here, the estimated fluxes fell within the range of natural
flux variabilities estimated with the component models.
BibTeX:
@article{maksyutov13a,
  author = {Maksyutov, S. and Takagi, H. and Valsala, V. K. and Saito, M. and Oda, T. and Saeki, T. and Belikov, D. A. and Saito, R. and Ito, A. and Yoshida, Y. and Morino, I. and Uchino, O. and Andres, R. J. and Yokota, T.},
  title = {Regional CO2 flux estimates for 2009-2010 based on GOSAT and ground-based CO2 observations},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {18},
  pages = {9351--9373},
  doi = {10.5194/acp-13-9351-2013}
}
Mallia DV, Lin JC, Urbanski S, Ehleringer J and Nehrkorn T ({2015}), "Impacts of upwind wildfire emissions on CO, CO2, and PM2.5 concentrations in Salt Lake City, Utah", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 16, {2015}. Vol. {120}({1}), pp. 147-166.
Abstract: Biomass burning is known to contribute large quantities of CO2, CO, and
PM2.5 to the atmosphere. Biomass burning not only affects the area in
the vicinity of fire but may also impact the air quality far downwind
from the fire. The 2007 and 2012 western U.S. wildfire seasons were
characterized by significant wildfire activity across much of the
Intermountain West and California. In this study, we determined the
locations of wildfire-derived emissions and their aggregate impacts on
Salt Lake City, a major urban center downwind of the fires. To determine
the influences of biomass burning emissions, we initiated an ensemble of
stochastic back trajectories at the Salt Lake City receptor within the
Stochastic Time-Inverted Lagrangian Transport (STILT) model, driven by
wind fields from the Weather Research and Forecasting (WRF) model. The
trajectories were combined with a new, high-resolution biomass burning
emissions inventorythe Wildfire Emissions Inventory. Initial results
showed that the WRF-STILT model was able to replicate many periods of
enhanced wildfire activity observed in the measurements. Most of the
contributions for the 2007 and 2012 wildfire seasons originated from
fires located in Utah and central Idaho. The model results suggested
that during intense episodes of upwind wildfires in 2007 and 2012, fires
contributed as much as 250ppb of CO during a 3 h period and 15 mu g/m(3)
of PM2.5 averaged over 24 h at Salt Lake City. Wildfires had a much
smaller impact on CO2 concentrations in Salt Lake City, with
contributions rarely exceeding 2ppm enhancements.
Key Points
BibTeX:
@article{mallia15a,
  author = {Mallia, D. V. and Lin, J. C. and Urbanski, S. and Ehleringer, J. and Nehrkorn, T.},
  title = {Impacts of upwind wildfire emissions on CO, CO2, and PM2.5 concentrations in Salt Lake City, Utah},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2015},
  volume = {120},
  number = {1},
  pages = {147--166},
  doi = {10.1002/2014JD022472}
}
Manning AC, Nisbet EG, Keeling RF and Liss PS ({2011}), "Greenhouse gases in the Earth system: setting the agenda to 2030", PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES., MAY 28, {2011}. Vol. {369}({1943}), pp. 1885-1890.
Abstract: What do we need to know about greenhouse gases? Over the next 20 years,
how should scientists study the role of greenhouse gases in the Earth
system and the changes that are taking place? These questions were
addressed at a Royal Society scientific Discussion Meeting in London on
22-23 February 2010, with over 300 participants.
BibTeX:
@article{manning11a,
  author = {Manning, Andrew C. and Nisbet, Euan G. and Keeling, Ralph F. and Liss, Peter S.},
  title = {Greenhouse gases in the Earth system: setting the agenda to 2030},
  journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES},
  year = {2011},
  volume = {369},
  number = {1943},
  pages = {1885--1890},
  doi = {10.1098/rsta.2011.0076}
}
Marino BD (2010), "System of systems for monitoring greenhouse gas fluxes".
BibTeX:
@misc{marino10a,
  author = {Marino, Bruno DV},
  title = {System of systems for monitoring greenhouse gas fluxes},
  publisher = {Google Patents},
  year = {2010},
  url = {https://patents.google.com/patent/US20100198736A1/en}
}
Marquis M and Tans P ({2008}), "Climate change - Carbon crucible", SCIENCE., APR 25, {2008}. Vol. {320}({5875}), pp. 460-461.
BibTeX:
@article{marquis08a,
  author = {Marquis, Melinda and Tans, Pieter},
  title = {Climate change - Carbon crucible},
  journal = {SCIENCE},
  year = {2008},
  volume = {320},
  number = {5875},
  pages = {460--461},
  doi = {10.1126/science.1156451}
}
Martin CR, Zeng N, Karion A, Mueller K, Ghosh S, Lopez-Coto I, Gurney KR, Oda T, Prasad K, Liu J, Dickerson R and Whetstone J (2019), "Investigating sources of variability and error in simulations of carbon dioxide in an urban region", ATMOSPHERIC ENVIRONMENT., FEB, 2019. Vol. 199, pp. 55-69.
BibTeX:
@article{martin19a,
  author = {Martin, Cory R. and Zeng, N. and Karion, A. and Mueller, K. and Ghosh, S. and Lopez-Coto, I. and Gurney, K. R. and Oda, T. and Prasad, K. and Liu, J. and Dickerson, R.R. and Whetstone, J.},
  title = {Investigating sources of variability and error in simulations of carbon dioxide in an urban region},
  journal = {ATMOSPHERIC ENVIRONMENT},
  year = {2019},
  volume = {199},
  pages = {55-69},
  url = {https://www.sciencedirect.com/science/article/pii/S1352231018307799}
}
Martins DK, Sweeney C, Stirm BH and Shepson PB ({2009}), "Regional surface flux of CO2 inferred from changes in the advected CO2 column density", AGRICULTURAL AND FOREST METEOROLOGY., OCT 1, {2009}. Vol. {149}({10}), pp. 1674-1685.
Abstract: A Lagrangian experiment was conducted over Iowa during the daytime
(9:00-17:30 LT) on June 19,2007 as part of the North American Carbon
Program's Mid-Continent Intensive using a light-weight and operationally
flexible aircraft to measure a net drawdown of CO2 concentration within
the boundary layer. The drawdown can be related to net ecosystem
exchange when anthropogenic emissions are estimated using a combination
of the Vulcan fossil fuel emissions inventory coupled with a source
contribution analysis using HYSPLIT. Results show a temporally and
spatially averaged net CO2 flux Of -9.0 +/- 2.4 mu mol m(-2) s(-1)
measured from the aircraft data. The average flux from anthropogenic
emissions over the measurement area was 0.3 +/- 0.1 mu mol CO2 m(-2)
s(-1). Large-scale subsidence occurred during the experiment, entraining
1.0 +/- 0.2 mu mol CO2 m(-2) s(-1) into the boundary layer. Thus, the
CO2 flux attributable to the vegetation and soils is -10.3 +/- 2.4 mu
mol m(-2) s(-1). The magnitude of the calculated daytime biospheric flux
is consistent with tower-based eddy covariance fluxes over corn and
soybeans given existing land-use estimates for this agricultural region.
Flux values are relatively insensitive to the choice of integration
height above the boundary layer and emission footprint area. Flux
uncertainties are relatively small compared to the biospheric fluxes,
though the measurements were conducted at the height of the growing
season. (C) 2009 Elsevier B.V. All rights reserved.
BibTeX:
@article{martins09a,
  author = {Martins, Douglas K. and Sweeney, Colm and Stirm, Brian H. and Shepson, Paul B.},
  title = {Regional surface flux of CO2 inferred from changes in the advected CO2 column density},
  journal = {AGRICULTURAL AND FOREST METEOROLOGY},
  year = {2009},
  volume = {149},
  number = {10},
  pages = {1674--1685},
  doi = {10.1016/j.agrformet.2009.05.005}
}
Martins DK (2009), "Development of methods for measurement of biosphere-atmosphere exchange of carbon and nitrogen". Thesis at: Purdue University.
BibTeX:
@phdthesis{martins09b,
  author = {Martins, Douglas K},
  title = {Development of methods for measurement of biosphere-atmosphere exchange of carbon and nitrogen},
  school = {Purdue University},
  year = {2009},
  url = {http://search.proquest.com/openview/fbdc1f23ed5696bf082a793577dd4459/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Masarie KA, Petron G, Andrews A, Bruhwiler L, Conway TJ, Jacobson AR, Miller JB, Tans PP, Worthy DE and Peters W ({2011}), "Impact of CO2 measurement bias on CarbonTracker surface flux estimates", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 9, {2011}. Vol. {116}
Abstract: For over 20 years, atmospheric measurements of CO2 dry air mole
fractions have been used to derive estimates of CO2 surface fluxes.
Historically, only a few research laboratories made these measurements.
Today, many laboratories are making CO2 observations using a variety of
analysis techniques and, in some instances, using different calibration
scales. As a result, the risk of biases in individual CO2 mole fraction
records, or even in complete monitoring networks, has increased over the
last decades. Ongoing experiments comparing independent, well-calibrated
measurements of atmospheric CO2 show that biases can and do exist
between measurement records. Biases in measurements create artificial
spatial and temporal CO2 gradients, which are then interpreted by an
inversion system, leading to erroneous flux estimates. Here we evaluate
the impact of a constant bias introduced into the National Oceanic and
Atmospheric Administration (NOAA) quasi-continuous measurement record at
the Park Falls, Wisconsin (LEF), tall tower site on CarbonTracker flux
estimates. We derive a linear relationship between the magnitude of the
introduced bias at LEF and the CarbonTracker surface flux responses.
Temperate North American net flux estimates are most sensitive to a bias
at LEF in our CarbonTracker inversion, and its linear response rate is
68 Tg C yr(-1) (similar to 10% of the estimated North American annual
terrestrial uptake) for every 1 ppm of bias in the LEF record. This
sensitivity increases when (1) measurement biases approached assumed
model errors and (2) fewer other measurement records are available to
anchor the flux estimates despite the presence of bias in one record.
Flux estimate errors are also calculated beyond North America. For
example, biospheric uptake in Europe and boreal Eurasia combined
increases by 25 Tg C yr(-1) per ppm CO2 to partially compensate for
changes in the North American flux totals. These results illustrate the
importance of well-calibrated, high-precision CO2 dry air mole fraction
measurements, as well as the value of an effective strategy for
detecting bias in measurements. This study stresses the need for a
monitoring network with the necessary density to anchor regional,
continental, and hemispheric fluxes more tightly and to lessen the
impact of potentially undetected biases in observational networks
operated by different national and international research programs.
BibTeX:
@article{masarie11a,
  author = {Masarie, K. A. and Petron, G. and Andrews, A. and Bruhwiler, L. and Conway, T. J. and Jacobson, A. R. and Miller, J. B. and Tans, P. P. and Worthy, D. E. and Peters, W.},
  title = {Impact of CO2 measurement bias on CarbonTracker surface flux estimates},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2011JD016270}
}
Masarie KA, Peters W, Jacobson AR and Tans PP ({2014}), "ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements", EARTH SYSTEM SCIENCE DATA. Vol. {6}({2}), pp. 375-384.
Abstract: Observation Package (ObsPack) is a framework designed to bring together
atmospheric greenhouse gas observations from a variety of sampling
platforms, prepare them with specific applications in mind, and package
and distribute them in a self-consistent and well-documented product.
Data products created using the ObsPack framework (called ``ObsPack
products'') are intended to support carbon cycle modeling studies and
represent a next generation of value-added greenhouse gas observation
products modeled after the cooperative GLOBALVIEW products introduced in
1996. Depending on intended use, ObsPack products may include data in
their original form reformatted using the ObsPack framework or may
contain derived data consisting of averages, subsets, or smoothed
representations of original data. All products include extensive
ancillary information (metadata) intended to help ensure the data are
used appropriately, their calibration and quality assurance history are
clearly described, and that individuals responsible for the measurements
(data providers or principal investigators (PIs)) are properly
acknowledged for their work. ObsPack products are made freely available
using a distribution strategy designed to improve communication between
data providers and product users. The strategy includes a data usage
policy that requires users to directly communicate with data providers
and an automated e-mail notification system triggered when a product is
accessed. ObsPack products will be assigned a unique digital object
identifier (DOI) to ensure each product can be unambiguously identified
in scientific literature. Here we describe the ObsPack framework and its
potential role in supporting the evolving needs of both data providers
and product users.
BibTeX:
@article{masarie14a,
  author = {Masarie, K. A. and Peters, W. and Jacobson, A. R. and Tans, P. P.},
  title = {ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements},
  journal = {EARTH SYSTEM SCIENCE DATA},
  year = {2014},
  volume = {6},
  number = {2},
  pages = {375--384},
  doi = {10.5194/essd-6-375-2014}
}
Medvigy D and Moorcroft PR ({2012}), "Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America", PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES., JAN 19, {2012}. Vol. {367}({1586}), pp. 222-235.
Abstract: Terrestrial biosphere models are important tools for diagnosing both the
current state of the terrestrial carbon cycle and forecasting
terrestrial ecosystem responses to global change. While there are a
number of ongoing assessments of the short-term predictive capabilities
of terrestrial biosphere models using flux-tower measurements, to date
there have been relatively few assessments of their ability to predict
longer term, decadal-scale biomass dynamics. Here, we present the
results of a regional-scale evaluation of the Ecosystem Demography
version 2 (ED2)-structured terrestrial biosphere model, evaluating the
model's predictions against forest inventory measurements for the
northeast USA and Quebec from 1985 to 1995. Simulations were conducted
using a default parametrization, which used parameter values from the
literature, and a constrained model parametrization, which had been
developed by constraining the model's predictions against 2 years of
measurements from a single site, Harvard Forest (42.5 degrees N, 72.1
degrees W). The analysis shows that the constrained model
parametrization offered marked improvements over the default model
formulation, capturing large-scale variation in patterns of biomass
dynamics despite marked differences in climate forcing, land-use history
and species-composition across the region. These results imply that
data-constrained parametrizations of structured biosphere models such as
ED2 can be successfully used for regional-scale ecosystem prediction and
forecasting. We also assess the model's ability to capture sub-grid
scale heterogeneity in the dynamics of biomass growth and mortality of
different sizes and types of trees, and then discuss the implications of
these analyses for further reducing the remaining biases in the model's
predictions.
BibTeX:
@article{medvigy12a,
  author = {Medvigy, David and Moorcroft, Paul R.},
  title = {Predicting ecosystem dynamics at regional scales: an evaluation of a terrestrial biosphere model for the forests of northeastern North America},
  journal = {PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES},
  year = {2012},
  volume = {367},
  number = {1586},
  pages = {222--235},
  doi = {10.1098/rstb.2011.0253}
}
Meirink JF, Bergamaschi P, Frankenberg C, d'Amelio MTS, Dlugokencky EJ, Gatti LV, Houweling S, Miller JB, Roeckmann T, Villani MG and Krol MC ({2008}), "Four-dimensional variational data assimilation for inverse modeling of atmospheric methane emissions: Analysis of SCIAMACHY observations", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., SEP 4, {2008}. Vol. {113}({D17})
Abstract: Recent observations from the Scanning Imaging Absorption Spectrometer
for Atmospheric Chartography (SCIAMACHY) instrument aboard ENVISAT have
brought new insights in the global distribution of atmospheric methane.
In particular, the observations showed higher methane concentrations in
the tropics than previously assumed. Here, we analyze the SCIAMACHY
observations and their implications for emission estimates in detail
using a four-dimensional variational (4D-Var) data assimilation system.
We focus on the period September to November 2003 and on the South
American continent, for which the satellite observations showed the
largest deviations from model simulations. In this set-up the advantages
of the 4D-Var approach and the zooming capability of the underlying TM5
atmospheric transport model are fully exploited. After application of a
latitude-dependent bias correction to the SCIAMACHY observations, the
assimilation system is able to accurately fit those observations, while
retaining consistency with a network of surface methane measurements.
The main emission increments resulting from the inversion are an
increase in the tropics, a decrease in South Asia, and a decrease at
northern hemispheric high latitudes. The SCIAMACHY observations yield
considerable additional emission uncertainty reduction, particularly in
the (sub-)tropical regions, which are poorly constrained by the surface
network. For tropical South America, the inversion suggests more than a
doubling of emissions compared to the a priori during the 3 months
considered. Extensive sensitivity experiments, in which key assumptions
of the inversion set-up are varied, show that this finding is robust.
Independent airborne observations in the Amazon basin support the
presence of considerable local methane sources. However, these
observations also indicate that emissions from eastern South America may
be smaller than estimated from SCIAMACHY observations. In this respect
it must be realized that the bias correction applied to the satellite
observations does not take into account potential regional systematic
errors, which - if identified in the future - will lead to shifts in the
overall distribution of emission estimates.
BibTeX:
@article{meirink08a,
  author = {Meirink, Jan Fokke and Bergamaschi, Peter and Frankenberg, Christian and d'Amelio, Monica T. S. and Dlugokencky, Edward J. and Gatti, Luciana V. and Houweling, Sander and Miller, John B. and Roeckmann, Thomas and Villani, M. Gabriella and Krol, Maarten C.},
  title = {Four-dimensional variational data assimilation for inverse modeling of atmospheric methane emissions: Analysis of SCIAMACHY observations},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2008},
  volume = {113},
  number = {D17},
  doi = {10.1029/2007JD009740}
}
Mekonnen ZA (2015), "Modeling the impacts of recent climate change on ecosystem productivity across North America". Thesis at: University of Alberta.
BibTeX:
@phdthesis{mekonnen15a,
  author = {Mekonnen, Zelalem A},
  title = {Modeling the impacts of recent climate change on ecosystem productivity across North America},
  school = {University of Alberta},
  year = {2015},
  url = {https://era.library.ualberta.ca/files/3r074x723}
}
Mekonnen ZA, Grant RF and Schwalm C ({2017}), "Carbon sources and sinks of North America as affected by major drought events during the past 30 years", AGRICULTURAL AND FOREST METEOROLOGY., OCT 15, {2017}. Vol. {244}, pp. 42-56.
Abstract: The North American (NA) terrestrial biosphere has been a long-term
carbon sink but impacts of climate extremes such as drought on ecosystem
carbon exchange remain largely uncertain. Here, changes in biospheric
carbon fluxes with recent climate change and impacts of the major
droughts of the past 30 years on continental carbon cycle across NA were
studied using a comprehensive mathematical process model, ecosys. In
test of these model responses at continental scale, the spatial
anomalies in modeled leaf area indices, fully prognostic in the model,
from long-term (1980-2010) means during major drought events in 1988 and
2002 agreed well with those in AVHRR NDVI (R-2 = 0.84 in 1988, 0.71 in
2002). Net ecosystem productivity (NEP) modeled across NA declined by
92% (0.50 Pg C yr(-1)) and 90% (0.49 Pg C yr(-1)) from the long-term
mean (+0.54 Pg C yr(-1)), in 1988 and 2002 respectively. These
significant drops in NEP offset 28% of the carbon gains modeled over
the last three decades. Although the long-term average modeled
terrestrial carbon sink was estimated to offset similar to 30% of the
fossil fuel emissions of NA, only 0.03% and 3.2% were offset in 1988
and 2002 leaving almost all fossil fuel emissions to the atmosphere.
These major drought events controlled much of the continental-scale
interannual variability and mainly occurred in parts of the Great
Plains, southwest US and northern Mexico. Although warming in northern
ecosystems caused increasing carbon sinks to be modeled as a result of
greater gross primary productivity with longer growing seasons,
elsewhere in the continent frequent drought events of the past 30 years
reduced carbon uptake and hence net carbon sinks of the NA.
BibTeX:
@article{mekonnen17a,
  author = {Mekonnen, Zelalem A. and Grant, Robert F. and Schwalm, Christopher},
  title = {Carbon sources and sinks of North America as affected by major drought events during the past 30 years},
  journal = {AGRICULTURAL AND FOREST METEOROLOGY},
  year = {2017},
  volume = {244},
  pages = {42--56},
  doi = {10.1016/j.agrformet.2017.05.006}
}
Mengistu AG and Mengistu Tsidu G (2018), "Comparison of CO2 from NOAA Carbon Tracker reanalysis model and satellites over Africa", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. 2018, pp. 1-31.
BibTeX:
@article{mengistua18a,
  author = {Mengistu, A. G. and Mengistu Tsidu, G.},
  title = {Comparison of CO2 from NOAA Carbon Tracker reanalysis model and satellites over Africa},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2018},
  volume = {2018},
  pages = {1-31},
  url = {https://www.atmos-meas-tech-discuss.net/amt-2018-84/amt-2018-84.pdf}
}
Messerschmidt J, Parazoo N, Wunch D, Deutscher NM, Roehl C, Warneke T and Wennberg PO ({2013}), "Evaluation of seasonal atmosphere-biosphere exchange estimations with TCCON measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({10}), pp. 5103-5115.
Abstract: We evaluate three estimates of the atmosphere-biosphere exchange against
total column CO2 observations from the Total Carbon Column Observing
Network (TCCON). Using the GEOS-Chem transport model, we produce forward
simulations of atmospheric CO2 concentrations for the 2006-2010 time
period using the Carnegie-Ames-Stanford Approach (CASA), the Simple
Biosphere (SiB) and the GBiome-BGC models. Large differences in the CO2
simulations result from the choice of the atmosphere-biosphere model. We
evaluate the seasonal cycle phase, amplitude and shape of the
simulations. The version of CASA currently used as the a priori model by
the GEOS-Chem carbon cycle community poorly represents the season cycle
in total column CO2. Consistent with earlier studies, enhancing the CO2
uptake in the boreal forest and shifting the onset of the growing season
earlier significantly improve the simulated seasonal CO2 cycle using
CASA estimates. The SiB model gives a better representation of the
seasonal cycle dynamics. The difference in the seasonality of net
ecosystem exchange (NEE) between these models is not the absolute gross
primary productivity (GPP), but rather the differential phasing of
ecosystem respiration (RE) with respect to GPP between these models.
BibTeX:
@article{messerschmidt13a,
  author = {Messerschmidt, J. and Parazoo, N. and Wunch, D. and Deutscher, N. M. and Roehl, C. and Warneke, T. and Wennberg, P. O.},
  title = {Evaluation of seasonal atmosphere-biosphere exchange estimations with TCCON measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {10},
  pages = {5103--5115},
  doi = {10.5194/acp-13-5103-2013}
}
Miles NL, Richardson SJ, Davis KJ, Lauvaux T, Andrews AE, West TO, Bandaru V and Crosson ER ({2012}), "Large amplitude spatial and temporal gradients in atmospheric boundary layer CO2 mole fractions detected with a tower-based network in the U.S. upper Midwest", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., FEB 21, {2012}. Vol. {117}
Abstract: This study presents observations of atmospheric boundary layer CO2 mole
fraction from a nine-tower regional network deployed during the North
American Carbon Program's Mid-Continent Intensive (MCI) during
2007-2009. The MCI region is largely agricultural, with well-documented
carbon exchange available via agricultural inventories. By combining
vegetation maps and tower footprints, we show the fractional influence
of corn, soy, grass, and forest biomes varies widely across the MCI.
Differences in the magnitude of CO2 flux from each of these biomes lead
to large spatial gradients in the monthly averaged CO2 mole fraction
observed in the MCI. In other words, the monthly averaged gradients are
tied to regional patterns in net ecosystem exchange (NEE). The daily
scale gradients are more weakly connected to regional NEE, instead being
governed by local weather and large-scale weather patterns. With this
network of tower-based mole fraction measurements, we detect
climate-driven interannual changes in crop growth that are confirmed by
satellite and inventory methods. These observations show that
regional-scale CO2 mole fraction networks yield large, coherent signals
governed largely by regional sources and sinks of CO2.
BibTeX:
@article{miles12a,
  author = {Miles, Natasha L. and Richardson, Scott J. and Davis, Kenneth J. and Lauvaux, Thomas and Andrews, Arlyn E. and West, Tristram O. and Bandaru, Varaprasad and Crosson, Eric R.},
  title = {Large amplitude spatial and temporal gradients in atmospheric boundary layer CO2 mole fractions detected with a tower-based network in the U.S. upper Midwest},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2011JG001781}
}
Miller SM, Matross DM, Andrews AE, Millet DB, Longo M, Gottlieb EW, Hirsch AI, Gerbig C, Lin JC, Daube BC, Hudman RC, Dias PLS, Chow VY and Wofsy SC ({2008}), "Sources of carbon monoxide and formaldehyde in North America determined from high-resolution atmospheric data", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {8}({24}), pp. 7673-7696.
Abstract: We analyze the North American budget for carbon monoxide using data for
CO and formaldehyde concentrations from tall towers and aircraft in a
model-data assimilation framework. The Stochastic Time-Inverted
Lagrangian Transport model for CO (STILT-CO) determines local to
regional-scale CO contributions associated with production from fossil
fuel combustion, biomass burning, and oxidation of volatile organic
compounds (VOCs) using an ensemble of Lagrangian particles driven by
high resolution assimilated meteorology. In many cases, the model
demonstrates high fidelity simulations of hourly surface data from tall
towers and point measurements from aircraft, with somewhat less
satisfactory performance in coastal regions and when CO from large
biomass fires in Alaska and the Yukon Territory influence the
continental US.
Inversions of STILT-CO simulations for CO and formaldehyde show that
current inventories of CO emissions from fossil fuel combustion are
significantly too high, by almost a factor of three in summer and a
factor two in early spring, consistent with recent analyses of data from
the INTEXA aircraft program. Formaldehyde data help to show that sources
of CO from oxidation of CH4 and other VOCs represent the dominant
sources of CO over North America in summer.
BibTeX:
@article{miller08a,
  author = {Miller, S. M. and Matross, D. M. and Andrews, A. E. and Millet, D. B. and Longo, M. and Gottlieb, E. W. and Hirsch, A. I. and Gerbig, C. and Lin, J. C. and Daube, B. C. and Hudman, R. C. and Dias, P. L. S. and Chow, V. Y. and Wofsy, S. C.},
  title = {Sources of carbon monoxide and formaldehyde in North America determined from high-resolution atmospheric data},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2008},
  volume = {8},
  number = {24},
  pages = {7673--7696},
  doi = {10.5194/acp-8-7673-2008}
}
Miller JB, Lehman SJ, Montzka SA, Sweeney C, Miller BR, Karion A, Wolak C, Dlugokencky EJ, Southon J, Turnbull JC and Tans PP ({2012}), "Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric (CO2)-C-14", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., APR 19, {2012}. Vol. {117}
Abstract: Atmospheric CO2 gradients are usually dominated by the signal from net
terrestrial biological fluxes, despite the fact that fossil fuel
combustion fluxes are larger in the annual mean. Here, we use a six year
long series of (CO2)-C-14 and CO2 measurements obtained from vertical
profiles at two northeast U.S. aircraft sampling sites to partition
lower troposphere CO2 enhancements (and depletions) into terrestrial
biological and fossil fuel components (C-bio and C-ff). Mean C-ff is 1.5
ppm, and 2.4 ppm when we consider only planetary boundary layer samples.
However, we find that the contribution of C-bio to CO2 enhancements is
large throughout the year, and averages 60% in winter. Paired
observations of C-ff and the lower troposphere enhancements (Delta(gas))
of 22 other anthropogenic gases (CH4, CO, halo- and hydrocarbons and
others) measured in the same samples are used to determine apparent
emission ratios for each gas. We then scale these ratios by the well
known U.S. fossil fuel CO2 emissions to provide observationally based
estimates of national emissions for each gas and compare these to
``bottom up'' estimates from inventories. Correlations of Delta(gas)
with C-ff for almost all gases are statistically significant with median
r(2) for winter, summer and the entire year of 0.59, 0.45, and 0.42,
respectively. Many gases exhibit statistically significant winter:
summer differences in ratios that indicate seasonality of emissions or
chemical destruction. The variability of ratios in a given season is not
readily attributable to meteorological or geographic variables and
instead most likely reflects real, short-term spatiotemporal variability
of emissions.
BibTeX:
@article{miller12a,
  author = {Miller, John B. and Lehman, Scott J. and Montzka, Stephen A. and Sweeney, Colm and Miller, Benjamin R. and Karion, Anna and Wolak, Chad and Dlugokencky, Ed J. and Southon, John and Turnbull, Jocelyn C. and Tans, Pieter P.},
  title = {Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric (CO2)-C-14},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2011JD017048}
}
Miller SM, Michalak AM and Levi PJ ({2014}), "Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {7}({1}), pp. 303-315.
Abstract: Many inverse problems in the atmospheric sciences involve parameters
with known physical constraints. Examples include nonnegativity (e. g.,
emissions of some urban air pollutants) or upward limits implied by
reaction or solubility constants. However, probabilistic inverse
modeling approaches based on Gaussian assumptions cannot incorporate
such bounds and thus often produce unrealistic results. The atmospheric
literature lacks consensus on the best means to overcome this problem,
and existing atmospheric studies rely on a limited number of the
possible methods with little examination of the relative merits of each.
This paper investigates the applicability of several approaches to
bounded inverse problems. A common method of data transformations is
found to unrealistically skew estimates for the examined example
application. The method of Lagrange multipliers and two Markov chain
Monte Carlo (MCMC) methods yield more realistic and accurate results. In
general, the examined MCMC approaches produce the most realistic result
but can require substantial computational time. Lagrange multipliers
offer an appealing option for large, computationally intensive problems
when exact uncertainty bounds are less central to the analysis. A
synthetic data inversion of US anthropogenic methane emissions
illustrates the strengths and weaknesses of each approach.
BibTeX:
@article{miller14a,
  author = {Miller, S. M. and Michalak, A. M. and Levi, P. J.},
  title = {Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2014},
  volume = {7},
  number = {1},
  pages = {303--315},
  doi = {10.5194/gmd-7-303-2014}
}
Miller SM, Hayek MN, Andrews AE, Fung I and Liu J ({2015}), "Biases in atmospheric CO2 estimates from correlated meteorology modeling errors", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({5}), pp. 2903-2914.
Abstract: Estimates of CO2 fluxes that are based on atmospheric measurements rely
upon a meteorology model to simulate atmospheric transport. These models
provide a quantitative link between the surface fluxes and CO2
measurements taken downwind. Errors in the meteorology can therefore
cause errors in the estimated CO2 fluxes. Meteorology errors that
correlate or covary across time and/or space are particularly worrisome;
they can cause biases in modeled atmospheric CO2 that are easily
confused with the CO2 signal from surface fluxes, and they are difficult
to characterize. In this paper, we leverage an ensemble of global
meteorology model outputs combined with a data assimilation system to
estimate these biases in modeled atmospheric CO2. In one case study, we
estimate the magnitude of month-long CO2 biases relative to CO2 boundary
layer enhancements and quantify how that answer changes if we either
include or remove error correlations or covariances. In a second case
study, we investigate which meteorological conditions are associated
with these CO2 biases.
In the first case study, we estimate uncertainties of 0.57 ppm in
monthly-averaged CO2 concentrations, depending upon location (95br> confidence interval). These uncertainties correspond to 13-150% of the
mean afternoon CO2 boundary layer enhancement at individual observation
sites. When we remove error covariances, however, this range drops to
222 %. Top-down studies that ignore these covariances could therefore
underestimate the uncertainties and/or propagate transport errors into
the flux estimate.
In the second case study, we find that these month-long errors in
atmospheric transport are anti-correlated with temperature and planetary
boundary layer (PBL) height over terrestrial regions. In marine
environments, by contrast, these errors are more strongly associated
with weak zonal winds. Many errors, however, are not correlated with a
single meteorological parameter, suggesting that a single meteorological
proxy is not sufficient to characterize uncertainties in atmospheric
CO2. Together, these two case studies provide information to improve the
setup of future top-down inverse modeling studies, preventing unforeseen
biases in estimated CO2 fluxes.
BibTeX:
@article{miller15a,
  author = {Miller, S. M. and Hayek, M. N. and Andrews, A. E. and Fung, I. and Liu, J.},
  title = {Biases in atmospheric CO2 estimates from correlated meteorology modeling errors},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {5},
  pages = {2903--2914},
  doi = {10.5194/acp-15-2903-2015}
}
Mingwei Z, Tianxiang Y, Xingying Z, Jinglu S, Ling J and Chun W ({2017}), "Fusion of multi-source near-surface CO2 concentration data based on high accuracy surface modeling", ATMOSPHERIC POLLUTION RESEARCH., NOV, {2017}. Vol. {8}({6}), pp. 1170-1178.
Abstract: Under the background of growing greenhouse gas emissions and the
resulting global warming, researches about the spatial-temporal
variation analysis of the concentration of carbon dioxide in the
regional and global scale has become one of the most important topics in
the scientific community. Simulating and analyzing the spatial-temporal
variation of the carbon dioxide concentration on a global scale under
limited observation data has become one of the key problems to be solved
in the research field of spatial analysis technology. A new research
approach based on high accuracy surface modeling data fusion (HASM-DF)
method was proposed in this paper, in which the output of the CO2
concentration of the GEOS-Chem model were taken as driving field, and
the observation values of CO2 concentration at ground observation
station were taken as accuracy control conditions. The new approach's
objective is to fulfill the fusion of the two kinds of CO2 data, and
obtain the distribution of CO2 on a global scale with a higher accuracy
than the results of GEOS-Chem. Root mean square error (RMSE) was chosen
as the basic accuracy index, and the experimental analysis shows that
the RMSE of the result of the proposed approach is 1.886 ppm, which is
significantly lower than that of the GEOS-Chem's 2.239 ppm. Furthermore,
compared with the results created by the interpolation methods used the
observation values at stations; the fusion results keep a good spatial
heterogeneity similar to the results of GEOS-Chem. This research
analyzed the spatial distribution and time series variation of the
near-surface CO2 based on the fusion result on a global scale. And it
can found that areas such as East Asia, Western North American, Central
South America and Central Africa and other region show a relatively high
value of the near-surface CO2 concentration. And we also found that the
near-surface CO2 concentration changes with season, especially in North
America and Eurasia, the near-surface CO2 in summer was significantly
lower than winter in these areas. (C) 2017 Turkish National Committee
for Air Pollution Research and Control. Production and hosting by
Elsevier B.V. All rights reserved.
BibTeX:
@article{mingwei17a,
  author = {Zhao Mingwei and Yue Tianxiang and Zhang Xingying and Sun Jinglu and Jiang Ling and Wang Chun},
  title = {Fusion of multi-source near-surface CO2 concentration data based on high accuracy surface modeling},
  journal = {ATMOSPHERIC POLLUTION RESEARCH},
  year = {2017},
  volume = {8},
  number = {6},
  pages = {1170--1178},
  doi = {10.1016/j.apr.2017.05.003}
}
Mitchell LE, Lin JC, Bowling DR, Pataki DE, Strong C, Schauer AJ, Bares R, Bush SE, Stephens BB, Mendoza D, Mallia D, Holland L, Gurney KR and Ehleringer JR ({2018}), "Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., MAR 20, {2018}. Vol. {115}({12}), pp. {2912-2917}.
Abstract: Cities are concentrated areas of CO2 emissions and have become the foci
of policies for mitigation actions. However, atmospheric measurement
networks suitable for evaluating urban emissions over time are scarce.
Here we present a unique long-term (decadal) record of CO2 mole
fractions from five sites across Utah's metropolitan Salt Lake Valley.
We examine ``excess'' CO2 above background conditions resulting from
local emissions and meteorological conditions. We ascribe CO2 trends to
changes in emissions, since we did not find long-term trends in
atmospheric mixing proxies. Three contrasting CO2 trends emerged across
urban types: negative trends at a residential-industrial site, positive
trends at a site surrounded by rapid suburban growth, and relatively
constant CO2 over time at multiple sites in the established,
residential, and commercial urban core. Analysis of population within
the atmospheric footprints of the different sites reveals approximately
equal increases in population influencing the observed CO2, implying a
nonlinear relationship with CO2 emissions: Population growth in rural
areas that experienced suburban development was associated with
increasing emissions while population growth in the developed urban core
was associated with stable emissions. Four state-of-the-art global-scale
emission inventories also have a nonlinear relationship with population
density across the city; however, in contrast to our observations, they
all have nearly constant emissions over time. Our results indicate that
decadal scale changes in urban CO2 emissions are detectable through
monitoring networks and constitute a valuable approach to evaluate
emission inventories and studies of urban carbon cycles.
BibTeX:
@article{mitchell18a,
  author = {Mitchell, Logan E. and Lin, John C. and Bowling, David R. and Pataki, Diane E. and Strong, Courtenay and Schauer, Andrew J. and Bares, Ryan and Bush, Susan E. and Stephens, Britton B. and Mendoza, Daniel and Mallia, Derek and Holland, Lacey and Gurney, Kevin R. and Ehleringer, James R.},
  title = {Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth},
  journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
  year = {2018},
  volume = {115},
  number = {12},
  pages = {2912-2917},
  doi = {{10.1073/pnas.1702393115}}
}
Mogollon R and Calil PHR ({2018}), "Counterintuitive effects of global warming-induced wind patterns on primary production in the Northern Humboldt Current System", GLOBAL CHANGE BIOLOGY., JUL, {2018}. Vol. {24}({7}), pp. {3187-3198}.
Abstract: It has been hypothesized that global warming will strengthen
upwelling-favorable winds in the Northern Humboldt Current System (NHCS)
as a consequence of the increase of the land-sea thermal gradient along
the Peruvian coast. The effect of strengthened winds in this region is
assessed with the use of a coupled physical-biogeochemical model forced
with projected and climatological winds. Strengthened winds induce an
increase in primary production of 2% per latitudinal degree from 9.5
degrees S to 5 degrees S. In some important coastal upwelling sites
primary production is reduced. This is due to a complex balance between
nutrient availability, nutrient use efficiency, as well as eddy- and
wind-driven factors. Mesoscale activity induces a net offshore transport
of inorganic nutrients, thus reducing primary production in the coastal
upwelling region. Wind mixing, in general disadvantageous for primary
producers, leads to shorter residence times in the southern and central
coastal zones. Overall, instead of a proportional enhancement in primary
production due to increased winds, the NHCS becomes only 5% more
productive (+5molCm(-2) year(-1)), 10% less limited by nutrients and
15% less efficient due to eddy-driven effects. It is found that regions
with a initial strong nutrient limitation are more efficient in terms of
nutrient assimilation which makes them more resilient in face of the
acceleration of the upwelling circulation.
BibTeX:
@article{mogollon18a,
  author = {Mogollon, Rodrigo and Calil, Paulo H. R.},
  title = {Counterintuitive effects of global warming-induced wind patterns on primary production in the Northern Humboldt Current System},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2018},
  volume = {24},
  number = {7},
  pages = {3187-3198},
  doi = {{10.1111/gcb.14171}}
}
van der Molen MK, de Jeu RAM, Wagner W, van der Velde IR, Kolari P, Kurbatova J, Varlagin A, Maximov TC, Kononov AV, Ohta T, Kotani A, Krol MC and Peters W ({2016}), "The effect of assimilating satellite-derived soil moisture data in SiBCASA on simulated carbon fluxes in Boreal Eurasia", HYDROLOGY AND EARTH SYSTEM SCIENCES. Vol. {20}({2}), pp. 605-624.
Abstract: Boreal Eurasia is a region where the interaction between droughts and
the carbon cycle may have significant impacts on the global carbon
cycle. Yet the region is extremely data sparse with respect to
meteorology, soil moisture, and carbon fluxes as compared to e.g.
Europe. To better constrain our vegetation model SiBCASA, we increase
data usage by assimilating two streams of satellite-derived soil
moisture. We study whether the assimilation improved SiBCASA's soil
moisture and its effect on the simulated carbon fluxes. By comparing to
unique in situ soil moisture observations, we show that the passive
microwave soil moisture product did not improve the soil moisture
simulated by SiBCASA, but the active data seem promising in some
aspects. The match between SiBCASA and ASCAT soil moisture is best in
the summer months over low vegetation. Nevertheless, ASCAT failed to
detect the major droughts occurring between 2007 and 2013. The
performance of ASCAT soil moisture seems to be particularly sensitive to
ponding, rather than to biomass. The effect on the simulated carbon
fluxes is large, 5-10% on annual GPP and TER, tens of percent on local
NEE, and 2% on area-integrated NEE, which is the same order of
magnitude as the inter-annual variations. Consequently, this study shows
that assimilation of satellite-derived soil moisture has potentially
large impacts, while at the same time further research is needed to
understand under which conditions the satellite-derived soil moisture
improves the simulated soil moisture.
BibTeX:
@article{molen16a,
  author = {van der Molen, M. K. and de Jeu, R. A. M. and Wagner, W. and van der Velde, I. R. and Kolari, P. and Kurbatova, J. and Varlagin, A. and Maximov, T. C. and Kononov, A. V. and Ohta, T. and Kotani, A. and Krol, M. C. and Peters, W.},
  title = {The effect of assimilating satellite-derived soil moisture data in SiBCASA on simulated carbon fluxes in Boreal Eurasia},
  journal = {HYDROLOGY AND EARTH SYSTEM SCIENCES},
  year = {2016},
  volume = {20},
  number = {2},
  pages = {605--624},
  doi = {10.5194/hess-20-605-2016}
}
Monteil G, Houweling S, Butz A, Guerlet S, Schepers D, Hasekamp O, Frankenberg C, Scheepmaker R, Aben I and Rockmann T ({2013}), "Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., OCT 27, {2013}. Vol. {118}({20}), pp. 11807-11823.
Abstract: [1] Over the past decade the development of Scanning Imaging
Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY)
retrievals has increased the interest in the use of satellite
measurements for studying the global sources and sinks of methane.
Meanwhile, measurements are becoming available from the more advanced
Greenhouse Gases Observing Satellite (GOSAT). The aim of this study is
to investigate the application of GOSAT retrievals to inverse modeling,
for which we make use of the TM5-4DVAR inverse modeling framework.
Inverse modeling calculations are performed using data from two
different retrieval approaches: a full physics and a lightpath proxy
ratio method. The performance of these inversions is analyzed in
comparison with inversions using SCIAMACHY retrievals and measurements
from the National Oceanic and Atmospheric Administration-Earth System
Research Laboratory flask-sampling network. In addition, we compare the
inversion results against independent surface, aircraft, and
total-column measurements. Inversions with GOSAT data show good
agreement with surface measurements, whereas for SCIAMACHY a similar
performance can only be achieved after significant bias corrections.
Some inconsistencies between surface and total-column methane remain in
the Southern Hemisphere. However, comparisons with measurements from the
Total Column Carbon Observing Network in situ Fourier transform
spectrometer network indicate that those may be caused by systematic
model errors rather than by shortcomings in the GOSAT retrievals. The
global patterns of methane emissions derived from SCIAMACHY (with bias
correction) and GOSAT retrievals are in remarkable agreement and allow
an increased resolution of tropical emissions. The satellite inversions
increase tropical methane emission by 30 to 60 Tg CH4/yr compared to
initial a priori estimates, partly counterbalanced by reductions in
emissions at midlatitudes to high latitudes.
BibTeX:
@article{monteil13a,
  author = {Monteil, Guillaume and Houweling, Sander and Butz, Andre and Guerlet, Sandrine and Schepers, Dinand and Hasekamp, Otto and Frankenberg, Christian and Scheepmaker, Remco and Aben, Ilse and Rockmann, Thomas},
  title = {Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2013},
  volume = {118},
  number = {20},
  pages = {11807--11823},
  doi = {10.1002/2013JD019760}
}
Montzka SA, Dlugokencky EJ and Butler JH ({2011}), "Non-CO2 greenhouse gases and climate change", NATURE., AUG 4, {2011}. Vol. {476}({7358}), pp. 43-50.
Abstract: Earth's climate is warming as a result of anthropogenic emissions of
greenhouse gases, particularly carbon dioxide (CO2) from fossil fuel
combustion. Anthropogenic emissions of non-CO2 greenhouse gases, such as
methane, nitrous oxide and ozone-depleting substances (largely from
sources other than fossil fuels), also contribute significantly to
warming. Some non-CO2 greenhouse gases have much shorter lifetimes than
CO2, so reducing their emissions offers an additional opportunity to
lessen future climate change. Although it is clear that sustainably
reducing the warming influence of greenhouse gases will be possible only
with substantial cuts in emissions of CO2, reducing non-CO2 greenhouse
gas emissions would be a relatively quick way of contributing to this
goal.
BibTeX:
@article{montzka11a,
  author = {Montzka, S. A. and Dlugokencky, E. J. and Butler, J. H.},
  title = {Non-CO2 greenhouse gases and climate change},
  journal = {NATURE},
  year = {2011},
  volume = {476},
  number = {7358},
  pages = {43--50},
  doi = {10.1038/nature10322}
}
Montzka S, Reimann S, O'Doherty S, Engel A, Krüger K and Sturges W (2011), "Ozone-depleting substances (ODSs) and related chemicals" World Meteorological Organization.
BibTeX:
@book{montzka11b,
  author = {Montzka, S and Reimann, SCLA and O'Doherty, S and Engel, A and Krüger, Kirstin and Sturges, WT},
  title = {Ozone-depleting substances (ODSs) and related chemicals},
  publisher = {World Meteorological Organization},
  year = {2011},
  url = {http://oceanrep.geomar.de/10405/2/03-Chapter_1.pdf}
}
Moore III B, Crowell SMR, Rayner PJ, Kumer J, O'Dell CW, O'Brien D, Utembe S, Polonsky I, Schimel D and Lemen J ({2018}), "The Potential of the Geostationary Carbon Cycle Observatory (GeoCarb) to Provide Multi-scale Constraints on the Carbon Cycle in the Americas", FRONTIERS IN ENVIRONMENTAL SCIENCE., OCT 17, {2018}. Vol. {6}
Abstract: The second NASA Earth Venture Mission, Geostationary Carbon Cycle
Observatory (GeoCarb), will provide measurements of atmospheric carbon
dioxide (CO2), methane (CH4), carbon monoxide (CO), and solar-induced
fluorescence (SIF) from Geostationary Orbit (GEO). The GeoCarb mission
will deliver daily maps of column concentrations of CO2, CH4, and CO
over the observed landmasses in the Americas at a spatial resolution of
roughly 10 x 10 km. Persistent measurements of CO2, CH4, CO, and SIF
will contribute significantly to resolving carbon emissions and
illuminating biotic processes at urban to continental scales, which will
allow the improvement of modeled biogeochemical processes in Earth
System Models as well as monitor the response of the biosphere to
disturbance. This is essential to improve understanding of the
Carbon-Climate connection. In this paper, we introduce the instrument
and the GeoCarb Mission, and we demonstrate the potential scientific
contribution of the mission through a series of CO2 and CH4 simulation
experiments. We find that GeoCarb will be able to constrain emissions at
urban to continental spatial scales on weekly to annual time scales. The
GeoCarb mission particularly builds upon the Orbiting Carbon
Obserevatory-2 (OCO-2), which is flying in Low Earth Orbit.
BibTeX:
@article{moore18a,
  author = {Moore, III, Berrien and Crowell, Sean M. R. and Rayner, Peter J. and Kumer, Jack and O'Dell, Christopher W. and O'Brien, Denis and Utembe, Steven and Polonsky, Igor and Schimel, David and Lemen, James},
  title = {The Potential of the Geostationary Carbon Cycle Observatory (GeoCarb) to Provide Multi-scale Constraints on the Carbon Cycle in the Americas},
  journal = {FRONTIERS IN ENVIRONMENTAL SCIENCE},
  year = {2018},
  volume = {6},
  doi = {{10.3389/fenvs.2018.00109}}
}
Moreira DS, Freitas SR, Bonatti JP, Mercado LM, Rosario NME, Longo KM, Miller JB, Gloor M and Gatti LV ({2013}), "Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO2 budget in South America", GEOSCIENTIFIC MODEL DEVELOPMENT. Vol. {6}({4}), pp. 1243-1259.
Abstract: This article presents the coupling of the JULES surface model to the
CCATT-BRAMS atmospheric chemistry model. This new numerical system is
denominated JULES-CCATT-BRAMS. We demonstrate the performance of this
new model system in relation to several meteorological variables and the
CO2 mixing ratio over a large part of South America, focusing on the
Amazon basin. The evaluation was conducted for two time periods, the wet
(March) and dry (September) seasons of 2010. The model errors were
calculated in relation to meteorological observations at conventional
stations in airports and automatic stations. In addition, CO2 mixing
ratios in the first model level were compared with meteorological tower
measurements and vertical CO2 profiles were compared with observations
obtained with airborne instruments. The results of this study show that
the JULES-CCATT-BRAMS modeling system provided a significant gain in
performance for the considered atmospheric fields relative to those
simulated by the LEAF (version 3) surface model originally employed by
CCATT-BRAMS. In addition, the new system significantly increases the
ability to simulate processes involving air-surface interactions, due to
the ability of JULES to simulate photosynthesis, respiration and dynamic
vegetation, among other processes. We also discuss a wide range of
numerical studies involving coupled atmospheric, land surface and
chemistry processes that could be done with the system introduced here.
Thus, this work presents to the scientific community a free modeling
tool, with good performance in comparison with observational data and
reanalysis model data, at least for the region and time period discussed
here. Therefore, in principle, this model is able to produce atmospheric
hindcast/forecast simulations at different spatial resolutions for any
time period and any region of the globe.
BibTeX:
@article{moreira13a,
  author = {Moreira, D. S. and Freitas, S. R. and Bonatti, J. P. and Mercado, L. M. and Rosario, N. M. E. and Longo, K. M. and Miller, J. B. and Gloor, M. and Gatti, L. V.},
  title = {Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO2 budget in South America},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2013},
  volume = {6},
  number = {4},
  pages = {1243--1259},
  doi = {10.5194/gmd-6-1243-2013}
}
Moreira DS, Longo KM, Freitas SR, Yamasoe MA, Mercado LM, Rosario NE, Gloor E, Viana RSM, Miller JB, Gatti LV, Wiedemann KT, Domingues LKG and Correia CCS ({2017}), "Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region", ATMOSPHERIC CHEMISTRY AND PHYSICS., DEC 12, {2017}. Vol. {17}({23}), pp. 14785-14810.
Abstract: Every year, a dense smoke haze covers a large portion of South America
originating from fires in the Amazon Basin and central parts of Brazil
during the dry biomass burning season between August and October. Over a
large portion of South America, the average aerosol optical depth at 550
nm exceeds 1.0 during the fire season, while the background value during
the rainy season is below 0.2. Biomass burning aerosol particles
increase scattering and absorption of the incident solar radiation. The
regional-scale aerosol layer reduces the amount of solar energy reaching
the surface, cools the near-surface air, and increases the diffuse
radiation fraction over a large disturbed area of the Amazon rainforest.
These factors affect the energy and CO2 fluxes at the surface. In this
work, we applied a fully integrated at-mospheric model to assess the
impact of biomass burning aerosols in CO2 fluxes in the Amazon region
during 2010. We address the effects of the attenuation of global solar
radiation and the enhancement of the diffuse solar radiation flux inside
the vegetation canopy. Our results indicate that biomass burning
aerosols led to increases of about 27% in the gross primary
productivity of Amazonia and 10% in plant respiration as well as a
decline in soil respiration of 3%. Consequently, in our model Amazonia
became a net carbon sink; net ecosystem exchange during September 2010
dropped from +101 to -104 TgC when the aerosol effects are considered,
mainly due to the aerosol diffuse radiation effect. For the forest
biome, our results point to a dominance of the diffuse radiation effect
on CO2 fluxes, reaching a balance of 50-50% between the diffuse and
direct aerosol effects for high aerosol loads. For C3 grasses and
savanna (cerrado), as expected, the contribution of the diffuse
radiation effect is much lower, tending to zero with the increase in
aerosol load. Taking all biomes together, our model shows the Amazon
during the dry season, in the presence of high biomass burning aerosol
loads, changing from being a source to being a sink of CO2 to the
atmosphere.
BibTeX:
@article{moreira17a,
  author = {Moreira, Demerval S. and Longo, Karla M. and Freitas, Saulo R. and Yamasoe, Marcia A. and Mercado, Lina M. and Rosario, Nilton E. and Gloor, Emauel and Viana, Rosane S. M. and Miller, John B. and Gatti, Luciana V. and Wiedemann, Kenia T. and Domingues, Lucas K. G. and Correia, Caio C. S.},
  title = {Modeling the radiative effects of biomass burning aerosols on carbon fluxes in the Amazon region},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {23},
  pages = {14785--14810},
  doi = {10.5194/acp-17-14785-2017}
}
Moro S, Danicic A, Alic N, Usechak NG and Radic S ({2011}), "Widely-tunable parametric short-wave infrared transmitter for CO2 trace detection", OPTICS EXPRESS., APR 25, {2011}. Vol. {19}({9}), pp. 8173-8178.
Abstract: An all-fiber, tunable, short-wave infrared transmitter is demonstrated
using efficient four-wave mixing in conventional L and O bands. To
realize this source a highly-nonlinear fiber, exhibiting low bend loss
over the short-wave infrared spectral band, is employed because of its
advantageous properties as a nonlinear mixing medium. The transmitter
was subsequently exploited to probe and detect trace levels of carbon
dioxide in the 2051-nm spectral region where its beam properties,
tunability, narrow linewidth, and stability all coalesce to permit this
application. This work indicates this transmitter can serve as a robust
source for sensing carbon dioxide and other trace gasses in the
short-wave infrared spectral region and should therefore play an
important role in future applications. (C) 2011 Optical Society of
America
BibTeX:
@article{moro11a,
  author = {Moro, Slaven and Danicic, Aleksandar and Alic, Nikola and Usechak, Nicholas G. and Radic, Stojan},
  title = {Widely-tunable parametric short-wave infrared transmitter for CO2 trace detection},
  journal = {OPTICS EXPRESS},
  year = {2011},
  volume = {19},
  number = {9},
  pages = {8173--8178},
  doi = {10.1364/OE.19.008173}
}
Moro S (2011), "Parametrically-aided sensing in the short-wave infrared frequency band and beyond". Thesis at: University of California San Diego.
BibTeX:
@phdthesis{moro11b,
  author = {Slaven Moro},
  title = {Parametrically-aided sensing in the short-wave infrared frequency band and beyond},
  school = {University of California San Diego},
  year = {2011},
  url = {http://search.proquest.com/openview/09a727bd0d87d88df6a4f2d824b3521b/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Mu M, Randerson JT, van der Werf GR, Giglio L, Kasibhatla P, Morton D, Collatz GJ, DeFries RS, Hyer EJ, Prins EM, Griffith DWT, Wunch D, Toon GC, Sherlock V and Wennberg PO ({2011}), "Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., DEC 24, {2011}. Vol. {116}
Abstract: Attribution of the causes of atmospheric trace gas and aerosol
variability often requires the use of high resolution time series of
anthropogenic and natural emissions inventories. Here we developed an
approach for representing synoptic-and diurnal-scale temporal
variability in fire emissions for the Global Fire Emissions Database
version 3 (GFED3). We disaggregated monthly GFED3 emissions during
2003-2009 to a daily time step using Moderate Resolution Imaging
Spectroradiometer (MODIS)-derived measurements of active fires from
Terra and Aqua satellites. In parallel, mean diurnal cycles were
constructed from Geostationary Operational Environmental Satellite
(GOES) Wildfire Automated Biomass Burning Algorithm (WFABBA) active
fire observations. Daily variability in fires varied considerably across
different biomes, with short but intense periods of daily emissions in
boreal ecosystems and lower intensity (but more continuous) periods of
burning in savannas. These patterns were consistent with earlier field
and modeling work characterizing fire behavior dynamics in different
ecosystems. On diurnal timescales, our analysis of the GOES WFABBA
active fires indicated that fires in savannas, grasslands, and croplands
occurred earlier in the day as compared to fires in nearby forests.
Comparison with Total Carbon Column Observing Network (TCCON) and
Measurements of Pollution in the Troposphere (MOPITT) column CO
observations provided evidence that including daily variability in
emissions moderately improved atmospheric model simulations,
particularly during the fire season and near regions with high levels of
biomass burning. The high temporal resolution estimates of fire
emissions developed here may ultimately reduce uncertainties related to
fire contributions to atmospheric trace gases and aerosols. Important
future directions include reconciling top-down and bottom up estimates
of fire radiative power and integrating burned area and active fire time
series from multiple satellite sensors to improve daily emissions
estimates.
BibTeX:
@article{mu11a,
  author = {Mu, M. and Randerson, J. T. and van der Werf, G. R. and Giglio, L. and Kasibhatla, P. and Morton, D. and Collatz, G. J. and DeFries, R. S. and Hyer, E. J. and Prins, E. M. and Griffith, D. W. T. and Wunch, D. and Toon, G. C. and Sherlock, V. and Wennberg, P. O.},
  title = {Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2011JD016245}
}
Muelleman A, Schell J, Glazer S and Glaser R (2016), "Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air", C. Vol. 2(3)
BibTeX:
@article{muelleman16a,
  author = {Muelleman, Andrew and Schell, Joseph and Glazer, Spencer and Glaser, Rainer},
  title = {Thermochemistry of a Biomimetic and Rubisco-Inspired CO2 Capture System from Air},
  journal = {C},
  year = {2016},
  volume = {2},
  number = {3},
  url = {http://www.mdpi.com/2311-5629/2/3/18/htm}
}
Mueller KL, Gourdji SM and Michalak AM ({2008}), "Global monthly averaged CO2 fluxes recovered using a geostatistical inverse modeling approach: 1. Results using atmospheric measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., NOV 12, {2008}. Vol. {113}({D21})
Abstract: This study presents monthly CO2 fluxes from 1997 to 2001 at a 3.75
degrees latitude x 5 degrees longitude resolution, inferred using a
geostatistical inverse modeling approach. The approach focuses on
quantifying the information content of measurements from the NOAA-ESRL
cooperative air sampling network with regard to the global CO2 budget at
different spatial and temporal scales. The geostatistical approach
avoids the use of explicit prior flux estimates that have formed the
basis of previous synthesis Bayesian inversions and does not prescribe
spatial patterns of flux for large, aggregated regions. Instead, the
method relies strongly on the atmospheric measurements and the inferred
spatial autocorrelation of the fluxes to estimate sources and sinks and
their associated uncertainties at the resolution of the atmospheric
transport model. Results show that grid-scale estimates exhibit high
uncertainty and relatively little small-scale variability, but generally
reflect reasonable fluxes in areas that are relatively well constrained
by measurements. The aggregated continental-scale fluxes are better
constrained, and estimates are consistent with results from previous
synthesis Bayesian inversion studies for many regions. Observed
differences at the continental scale are primarily attributable to the
choice of a priori assumptions in the current work relative to those in
other synthesis Bayesian studies. Overall, the results indicate that the
geostatistical inverse modeling approach is able to estimate global
fluxes using the limited atmospheric measurement network without relying
on assumptions about a priori estimates of the flux distribution. As
such, the method provides a means of isolating the information content
of the atmospheric measurements, and thus serves as a valuable tool for
reconciling top-down and bottom-up estimates of CO2 flux variability.
BibTeX:
@article{mueller08a,
  author = {Mueller, Kim L. and Gourdji, Sharon M. and Michalak, Anna M.},
  title = {Global monthly averaged CO2 fluxes recovered using a geostatistical inverse modeling approach: 1. Results using atmospheric measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2008},
  volume = {113},
  number = {D21},
  doi = {10.1029/2007JD009734}
}
Mueller KL (2011), "A data-driven multi-scale statistical investigation of regional sources and sinks to improve knowledge of terrestrial carbon cycling". Thesis at: University of Michigan.
BibTeX:
@phdthesis{mueller11a,
  author = {Mueller, Kimberly L},
  title = {A data-driven multi-scale statistical investigation of regional sources and sinks to improve knowledge of terrestrial carbon cycling},
  school = {University of Michigan},
  year = {2011},
  url = {http://search.proquest.com/openview/df727968d2cc116d449bf05fe1596bb9/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Mueller K, Yadav V, Lopez-Coto I, Karion A, Gourdji S, Martin C and Whetstone J ({2018}), "Siting Background Towers to Characterize Incoming Air for Urban Greenhouse Gas Estimation: A Case Study in the Washington, DC/Baltimore Area", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 16, {2018}. Vol. {123}({5}), pp. {2910-2926}.
Abstract: There is increased interest in understanding urban greenhouse gas (GHG)
emissions. To accurately estimate city emissions, the influence of
extraurban fluxes must first be removed from urban greenhouse gas (GHG)
observations. This is especially true for regions, such as the U.S.
Northeastern Corridor-Baltimore/Washington, DC (NEC-B/W), downwind of
large fluxes. To help site background towers for the NEC-B/W, we use a
coupled Bayesian Information Criteria and geostatistical regression
approach to help site four background locations that best explain CO2
variability due to extraurban fluxes modeled at 12 urban towers. The
synthetic experiment uses an atmospheric transport and dispersion model
coupled with two different flux inventories to create modeled
observations and evaluate 15 candidate towers located along the urban
domain for February and July 2013. The analysis shows that the average
ratios of extraurban inflow to total modeled enhancements at urban
towers are 21% to 36% in February and 31% to 43% in July. In July,
the incoming air dominates the total variability of synthetic
enhancements at the urban towers (R-2=0.58). Modeled observations from
the selected background towers generally capture the variability in the
synthetic CO2 enhancements at urban towers (R-2=0.75, root-mean-square
error (RMSE)=3.64ppm; R-2=0.43, RMSE=4.96ppm for February and July).
However, errors associated with representing background air can be up to
10ppm for any given observation even with an optimal background tower
configuration. More sophisticated methods may be necessary to represent
background air to accurately estimate urban GHG emissions.
BibTeX:
@article{mueller18a,
  author = {Mueller, K. and Yadav, V. and Lopez-Coto, I. and Karion, A. and Gourdji, S. and Martin, C. and Whetstone, J.},
  title = {Siting Background Towers to Characterize Incoming Air for Urban Greenhouse Gas Estimation: A Case Study in the Washington, DC/Baltimore Area},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2018},
  volume = {123},
  number = {5},
  pages = {2910-2926},
  doi = {{10.1002/2017JD027364}}
}
Nalini K, Uma K, Sijikumar S, Tiwari YK and Ramachandran R (2018), "Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies, spatial variability, and model estimates", INTERNATIONAL JOURNAL OF REMOTE SENSING., JUN, 2018. Vol. 39(22), pp. 7881-7900.
BibTeX:
@article{nalini18a,
  author = {Nalini, K. and Uma, K.N. and Sijikumar, S. and Tiwari, Yogesh K. and Ramachandran, Radhika},
  title = {Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies, spatial variability, and model estimates},
  journal = {INTERNATIONAL JOURNAL OF REMOTE SENSING},
  year = {2018},
  volume = {39},
  number = {22},
  pages = {7881-7900},
  url = {https://www.tandfonline.com/doi/abs/10.1080/01431161.2018.1479787}
}
Nassar R, Jones DBA, Kulawik SS, Worden JR, Bowman KW, Andres RJ, Suntharalingam P, Chen JM, Brenninkmeijer CAM, Schuck TJ, Conway TJ and Worthy DE ({2011}), "Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {11}({12}), pp. 6029-6047.
Abstract: We infer CO2 surface fluxes using satellite observations of
mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES)
and measurements of CO2 from surface flasks in a time-independent
inversion analysis based on the GEOS-Chem model. Using TES CO2
observations over oceans, spanning 40 degrees S-40 degrees N, we find
that the horizontal and vertical coverage of the TES and flask data are
complementary. This complementarity is demonstrated by combining the
datasets in a joint inversion, which provides better constraints than
from either dataset alone, when a posteriori CO2 distributions are
evaluated against independent ship and aircraft CO2 data. In particular,
the joint inversion offers improved constraints in the tropics where
surface measurements are sparse, such as the tropical forests of South
America. Aggregating the annual surface-to-atmosphere fluxes from the
joint inversion for the year 2006 yields -1.13 +/- 0.21 PgC for the
global ocean, -2.77 +/- 0.20 PgC for the global land biosphere and -3.90
+/- 0.29 PgC for the total global natural flux (defined as the sum of
all biospheric, oceanic, and biomass burning contributions but excluding
CO2 emissions from fossil fuel combustion). These global ocean and
global land fluxes are shown to be near the median of the broad range of
values from other inversion results for 2006. To achieve these results,
a bias in TES CO2 in the Southern Hemisphere was assessed and corrected
using aircraft flask data, and we demonstrate that our results have low
sensitivity to variations in the bias correction approach. Overall, this
analysis suggests that future carbon data assimilation systems can
benefit by integrating in situ and satellite observations of CO2 and
that the vertical information provided by satellite observations of
mid-tropospheric CO2 combined with measurements of surface CO2, provides
an important additional constraint for flux inversions.
BibTeX:
@article{nassar11a,
  author = {Nassar, R. and Jones, D. B. A. and Kulawik, S. S. and Worden, J. R. and Bowman, K. W. and Andres, R. J. and Suntharalingam, P. and Chen, J. M. and Brenninkmeijer, C. A. M. and Schuck, T. J. and Conway, T. J. and Worthy, D. E.},
  title = {Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2011},
  volume = {11},
  number = {12},
  pages = {6029--6047},
  doi = {10.5194/acp-11-6029-2011}
}
Nassar R, Napier-Linton L, Gurney KR, Andres RJ, Oda T, Vogel FR and Deng F ({2013}), "Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission data sets", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JAN 27, {2013}. Vol. {118}({2}), pp. 917-933.
Abstract: Through an analysis of multiple global fossil fuel CO2 emission data
sets, Vulcan emission data for the United States, Canada's National
Inventory Report, and NO2 variability based on satellite observations,
we derive scale factors that can be applied to global emission data sets
to represent weekly and diurnal CO2 emission variability. This is
important for inverse modeling and data assimilation of CO2, which use
in situ or satellite measurements subject to variability on these time
scales. Model simulations applying the weekly and diurnal scaling show
that, although the impacts are minor far away from sources, surface
atmospheric CO2 is perturbed by up to 1.5-8 ppm and column-averaged CO2
is perturbed by 0.1-0.5 ppm over some major cities, suggesting the
magnitude of model biases for urban areas when these modes of temporal
variability are not represented. In addition, we also derive scale
factors to account for the large per capita differences in CO2 emissions
between Canadian provinces that arise from differences in per capita
energy use and the proportion of energy generated by methods that do not
emit CO2, which are not accounted for in population-based global
emission data sets. The resulting products of these analyses are global
0.25 degrees x 0.25 degrees gridded scale factor maps that can be
applied to global fossil fuel CO2 emission data sets to represent weekly
and diurnal variability and 1 degrees x 1 degrees scale factor maps to
redistribute spatially emissions from two common global data sets to
account for differences in per capita emissions within Canada.
BibTeX:
@article{nassar13a,
  author = {Nassar, Ray and Napier-Linton, Louis and Gurney, Kevin R. and Andres, Robert J. and Oda, Tomohiro and Vogel, Felix R. and Deng, Feng},
  title = {Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission data sets},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2013},
  volume = {118},
  number = {2},
  pages = {917--933},
  doi = {10.1029/2012JD018196}
}
Nassar R, Sioris CE, Jones DBA and McConnell JC ({2014}), "Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., MAR 16, {2014}. Vol. {119}({5}), pp. 2654-2673.
Abstract: Here we report on an observing system simulation experiment (OSSE) to
compare the efficacy of near-infrared satellite observations of CO2 from
a highly elliptical orbit (HEO) and a low Earth orbit (LEO), for
constraining Arctic and boreal CO2 sources and sinks. The carbon cycle
at these latitudes (similar to 50-90 degrees N) is primarily driven by
the boreal forests, but increasing anthropogenic activity and the
effects of climate change such as thawing of permafrost throughout this
region could also have an important role in the coming years. A HEO
enables quasi-geostationary observations of Earth's northern high
latitudes, which are not observed from a geostationary orbit. The orbit
and observing characteristics for the HEO mission are based on the
Weather, Climate and Air quality (WCA) concept proposed for the Polar
Communications and Weather (PCW) mission, while those for the LEO
mission are based on the Greenhouse gases Observing Satellite (GOSAT).
Two WCA instrument configurations were investigated. Adopting the
Optimal configuration yielded an observation data set that gave annual
Arctic and boreal regional terrestrial biospheric CO2 flux uncertainties
an average of 30% lower than those from GOSAT, while a smaller
instrument configuration resulted in uncertainties averaging 20% lower
than those from GOSAT. For either WCA instrument configuration, much
greater reductions in uncertainty occur for spring, summer, and autumn
than for winter, with Optimal flux uncertainties for June-August nearly
50% lower than from GOSAT. These findings demonstrate that CO2
observations from HEO offer significant advantages over LEO for
constraining CO2 fluxes from the Arctic and boreal regions.
Key Points

Highly elliptical orbit (HEO)
satellites can improve high-latitude coverage id=''jgrd51170-li-0002''>We conduct flux inversions with simulated
CO2 from GOSAT and a HEO mission id=''jgrd51170-li-0003''>HEO offers major advantages for
constraining Arctic and boreal CO2 fluxes
BibTeX:
@article{nassar14a,
  author = {Nassar, Ray and Sioris, Chris E. and Jones, Dylan B. A. and McConnell, John C.},
  title = {Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2014},
  volume = {119},
  number = {5},
  pages = {2654--2673},
  doi = {10.1002/2013JD020337}
}
Negra C, Sweedo CC, Cavender-Bares K and O'Malley R ({2008}), "Indicators of carbon storage in US ecosystems: Baseline for terrestrial carbon", JOURNAL OF ENVIRONMENTAL QUALITY., JUL-AUG, {2008}. Vol. {37}({4}), pp. 1376-1382.
Abstract: Policymakers, program managers, and landowners need information about
net terrestrial carbon sequestration in forests, croplands, grasslands,
and shrublands to understand the cumulative effects of carbon trading
programs, expanding biofuels production, and changing environmental
conditions in addition to agricultural and forestry uses. Objective
information systems that establish credible baselines and track changes
in carbon storage can provide the accountability needed for carbon
trading programs to achieve durable carbon sequestration and for
biofuels initiatives to reduce net greenhouse gas emissions. A
multi-sector stakeholder design process was used to produce a new
indicator for the 2008 State of the Nation's Ecosystems report that
presents metrics of carbon storage for major ecosystem types,
specifically change in the amount of carbon gained or lost over time and
the amount of carbon stored per unit area (carbon density). These
metrics have been developed for national scale use, but are suitable for
adaptation to multiple scales such as individual farm and forest
parcels, carbon offset markets and integrated national and international
assessments. To acquire the data necessary for a complete understanding
of how much, and where, carbon is gained or lost by U.S. ecosystems,
expansion and integration of monitoring programs will be required.
BibTeX:
@article{negra08a,
  author = {Negra, Christine and Sweedo, Caroline Cremer and Cavender-Bares, Kent and O'Malley, Robin},
  title = {Indicators of carbon storage in US ecosystems: Baseline for terrestrial carbon},
  journal = {JOURNAL OF ENVIRONMENTAL QUALITY},
  year = {2008},
  volume = {37},
  number = {4},
  pages = {1376--1382},
  note = {4th USDA Greenhouse Gas Symposium on Positioning Agriculture and Forestry to Meet the Challenges of Climate Change, Baltimore, MD, FEB 06-08, 2007},
  doi = {10.2134/jeq2007.0290}
}
Nelson RR, O'Dell CW, Taylor TE, Mandrake L and Smyth M ({2016}), "The potential of clear-sky carbon dioxide satellite retrievals", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({4}), pp. 1671-1684.
Abstract: Since the launch of the Greenhouse Gases Observing Satellite (GOSAT) in
2009, retrieval algorithms designed to infer the column-averaged dry-air
mole fraction of carbon dioxide (X-CO2) from hyperspectral near-infrared
observations of reflected sunlight have been greatly improved. They now
generally include the scattering effects of clouds and aerosols, as
early work found that absorption-only retrievals, which neglected these
effects, often incurred unacceptably large errors, even for scenes with
optically thin cloud or aerosol layers. However, these
``full-physics'' retrievals tend to be computationally expensive and
may incur biases from trying to deduce the properties of clouds and
aerosols when there are none present. Additionally, algorithms are now
available that can quickly and effectively identify and remove most
scenes in which cloud or aerosol scattering plays a significant role.
In this work, we test the hypothesis that non-scattering, or
``clear-sky'', retrievals may perform as well as full-physics
retrievals for sufficiently clear scenes. Clear-sky retrievals could
potentially avoid errors and biases brought about by trying to infer
properties of clouds and aerosols when none are present. Clear-sky
retrievals are also desirable because they are orders of magnitude
faster than full-physics retrievals. Here we use a simplified version of
the Atmospheric Carbon Observations from Space (ACOS) X-CO2 retrieval
algorithm that does not include the scattering and absorption effects of
clouds or aerosols. It was found that for simulated Orbiting Carbon
Observatory-2 (OCO-2) measurements, the clear-sky retrieval had errors
comparable to those of the full-physics retrieval. For real GOSAT data,
the clear-sky retrieval had errors 0-20% larger than the full-physics
retrieval over land and errors roughly 20-35% larger over ocean,
depending on filtration level. In general, the clear-sky retrieval had
X-CO2 root-mean-square errors (RMSEs) of less than 2.0 ppm, relative to
Total Carbon Column Observing Network (TCCON) measurements and a suite
of CO2 models, when adequately filtered through the use of a custom
genetic algorithm filtering system. These results imply that
non-scattering X-CO2 retrievals are potentially more useful than
previous literature suggests, as the filtering methods we employ are
able to remove measurements in which scattering can cause significant
errors. Additionally, the computational benefits of non-scattering
retrievals means they may be useful for certain applications that
require large amounts of data but have less stringent error
requirements.
BibTeX:
@article{nelson16a,
  author = {Nelson, Robert R. and O'Dell, Christopher W. and Taylor, Thomas E. and Mandrake, Lukas and Smyth, Mike},
  title = {The potential of clear-sky carbon dioxide satellite retrievals},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {4},
  pages = {1671--1684},
  doi = {10.5194/amt-9-1671-2016}
}
Nelson KS (2016), "Biofilm response to ocean acidification and the effects on serpulid polychaete settlement". Thesis at: University of Otago.
BibTeX:
@mastersthesis{nelson16b,
  author = {Nelson, Kathryn Sarah},
  title = {Biofilm response to ocean acidification and the effects on serpulid polychaete settlement},
  school = {University of Otago},
  year = {2016},
  url = {https://otago.ourarchive.ac.nz/handle/10523/6783}
}
Nevison C, Andrews A, Thoning K, Dlugokencky E, Sweeney C, Miller S, Saikawa E, Benmergui J, Fischer M, Mountain M and Nehrkorn T ({2018}), "Nitrous Oxide Emissions Estimated With the CarbonTracker-Lagrange North American Regional Inversion Framework", GLOBAL BIOGEOCHEMICAL CYCLES., MAR, {2018}. Vol. {32}({3}), pp. {463-485}.
Abstract: North American nitrous oxide (N2O) emissions of 1.60.3TgN/yr over
2008-2014 are estimated using the CarbonTracker-Lagrange regional
inversion framework. The estimated N2O emissions are largely consistent
with the EDGAR (Emission Database for Global Atmospheric Research)
global inventory and with the results of global atmospheric inversions
but offer more spatial and temporal detail over North America. Emissions
are strongest from the Midwestern Corn/Soybean Belt, which accounts for
nearly one third of the total North American N2O source. The emissions
are maximum in spring/early summer, consistent with a nitrogen
fertilizer-driven source, and also show a late winter spike suggestive
of freeze-thaw effects. Interannual variability in emissions across the
primary months of fertilizer application is positively correlated to
mean precipitation. The estimated N2O flux from the Midwestern
Corn/Soybean Belt and the more northerly United States/Canadian wheat
belt corresponds to 4.2-4.6% and 2.2-3.0 respectively, of total
synthetic+organic N fertilizer applied to those regions. Consideration
of nonagricultural sources and additional N inputs from soybean N-2
fixation could reduce the N2O yield from the Midwestern Corn/Soybean
Belt to similar to 2.2-2.4% of total N inputs.
Plain Language Summary Emissions of nitrous oxide (N2O) emissions over
North America were estimated based on an inverse model, in which
atmospheric concentrations of N2O measured at 40 different National
Oceanographic Atmospheric Administration (NOAA) sites were inverted to
estimate surface sources. The estimated N2O emissions showed a clear hot
spot in the Midwestern corn/soybean belt, which accounted for nearly one
third (0.48 0.02 x 10(12)gN/yr) of the total North American N2O source
(1.6 0.3x10(12)gN/yr). The emissions were maximum in spring and early
summer, consistent with the timing of nitrogen fertilizer application to
the corn/soybean belt. Interannual variability across 2007-2015 in the
inferred emissions suggested that climate may interact with fertilizer
to influence N2O source strength, with the warm drought year 2012
showing substantially lower emissions than other years.
BibTeX:
@article{nevison18a,
  author = {Nevison, Cynthia and Andrews, Arlyn and Thoning, Kirk and Dlugokencky, Ed and Sweeney, Colm and Miller, Scot and Saikawa, Eri and Benmergui, Joshua and Fischer, Marc and Mountain, Marikate and Nehrkorn, Thomas},
  title = {Nitrous Oxide Emissions Estimated With the CarbonTracker-Lagrange North American Regional Inversion Framework},
  journal = {GLOBAL BIOGEOCHEMICAL CYCLES},
  year = {2018},
  volume = {32},
  number = {3},
  pages = {463-485},
  doi = {{10.1002/2017GB005759}}
}
Nguyen H, Osterman G, Wunch D, O'Dell C, Mandrake L, Wennberg P, Fisher B and Castano R ({2014}), "A method for colocating satellite X-CO2 data to ground-based data and its application to ACOS-GOSAT and TCCON", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {7}({8}), pp. 2631-2644.
Abstract: Satellite measurements are often compared with higher-precision
ground-based measurements as part of validation efforts. The satellite
soundings are rarely perfectly coincident in space and time with the
ground-based measurements, so a colocation methodology is needed to
aggregate ``nearby'' soundings into what the instrument would have
seen at the location and time of interest. We are particularly
interested in validation efforts for satellite-retrieved total column
carbon dioxide (X-CO2), where X-CO2 data from Greenhouse Gas Observing
Satellite (GOSAT) retrievals (ACOS, NIES, RemoteC, PPDF, etc.) or
SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY
(SCIA-MACHY) are often colocated and compared to ground-based column
X-CO2 measurement from Total Carbon Column Observing Network (TCCON).
Current colocation methodologies for comparing satellite measurements of
total column dry-air mole fractions of CO2 (X-CO2) with ground-based
measurements typically involve locating and averaging the satellite
measurements within a latitudinal, longitudinal, and temporal window. We
examine a geostatistical colocation methodology that takes a weighted
average of satellite observations depending on the ``distance'' of
each observation from a ground-based location of interest. The
``distance'' function that we use is a modified Euclidian distance
with respect to latitude, longitude, time, and midtropospheric
temperature at 700 hPa. We apply this methodology to X-CO2 retrieved
from GOSAT spectra by the ACOS team, cross-validate the results to TCCON
X-CO2 ground-based data, and present some comparisons between our
methodology and standard existing colocation methods showing that, in
general, geostatistical colocation produces smaller mean-squared error.
BibTeX:
@article{nguyen14a,
  author = {Nguyen, H. and Osterman, G. and Wunch, D. and O'Dell, C. and Mandrake, L. and Wennberg, P. and Fisher, B. and Castano, R.},
  title = {A method for colocating satellite X-CO2 data to ground-based data and its application to ACOS-GOSAT and TCCON},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2014},
  volume = {7},
  number = {8},
  pages = {2631--2644},
  doi = {10.5194/amt-7-2631-2014}
}
Niu S, Luo Y, Fei S, Montagnani L, Bohrer G, Janssens IA, Gielen B, Rambal S, Moors E and Matteucci G ({2011}), "Seasonal hysteresis of net ecosystem exchange in response to temperature change: patterns and causes", GLOBAL CHANGE BIOLOGY., OCT, {2011}. Vol. {17}({10}), pp. 3102-3114.
Abstract: Understanding how net ecosystem exchange (NEE) changes with temperature
is central to the debate on climate change-carbon cycle feedbacks, but
still remains unclear. Here, we used eddy covariance measurements of NEE
from 20 FLUXNET sites (203 site-years of data) in mid-and high-latitude
forests to investigate the temperature response of NEE. Years were
divided into two half thermal years (increasing temperature in spring
and decreasing temperature in autumn) using the maximum daily mean
temperature. We observed a parabolic-like pattern of NEE in response to
temperature change in both the spring and autumn half thermal years.
However, at similar temperatures, NEE was considerably depressed during
the decreasing temperature season as compared with the increasing
temperature season, inducing a counter-clockwise hysteresis pattern in
the NEE-temperature relation at most sites. The magnitude of this
hysteresis was attributable mostly (68 to gross primary production
(GPP) differences but little (8 to ecosystem respiration (ER)
differences between the two half thermal years. The main environmental
factors contributing to the hysteresis responses of NEE and GPP were
daily accumulated radiation. Soil water content (SWC) also contributed
to the hysteresis response of GPP but only at some sites. Shorter day
length, lower light intensity, lower SWC and reduced photosynthetic
capacity may all have contributed to the depressed GPP and net carbon
uptake during the decreasing temperature seasons. The resultant
hysteresis loop is an important indicator of the existence of limiting
factors. As such, the role of radiation, LAI and SWC should be
considered when modeling the dynamics of carbon cycling in response to
temperature change.
BibTeX:
@article{niu11a,
  author = {Niu, Shuli and Luo, Yiqi and Fei, Shenfeng and Montagnani, Leonardo and Bohrer, Gil and Janssens, Ivan A. and Gielen, Bert and Rambal, Serge and Moors, Eddy and Matteucci, Giorgio},
  title = {Seasonal hysteresis of net ecosystem exchange in response to temperature change: patterns and causes},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2011},
  volume = {17},
  number = {10},
  pages = {3102--3114},
  doi = {10.1111/j.1365-2486.2011.02459.x}
}
Niwa Y, Machida T, Sawa Y, Matsueda H, Schuck TJ, Brenninkmeijer CAM, Imasu R and Satoh M ({2012}), "Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 5, {2012}. Vol. {117}
Abstract: Because very few measurements of atmospheric carbon dioxide (CO2) are
available in the tropics, estimates of surface CO2 fluxes in tropical
regions are beset with considerable uncertainties. To improve estimates
of tropical terrestrial fluxes, atmospheric CO2 inversion was performed
using passenger aircraft based measurements of the Comprehensive
Observation Network for Trace gases by Airliner (CONTRAIL) project in
addition to the surface measurement data set of GLOBALVIEW-CO2. Regional
monthly fluxes at the earth's surface were estimated using the Bayesian
synthesis approach focusing on the period 2006-2008 using the
Nonhydrostatic Icosahedral Atmospheric Model-based Transport Model
(NICAM-TM). By adding the aircraft to the surface data, the posterior
flux errors were greatly reduced; specifically, error reductions of up
to 64% were found for tropical Asia regions. This strong impact is
closely related to efficient vertical transport in the tropics. The
optimized surface fluxes using the CONTRAIL data were evaluated by
comparing the simulated atmospheric CO2 distributions with independent
aircraft measurements of the Civil Aircraft for the Regular
Investigation of the atmosphere Based on an Instrument Container
(CARIBIC) project. The inversion with the CONTRAIL data yields the
global carbon sequestration rates of 2.22 +/- 0.28 Pg C yr(-1) for the
terrestrial biosphere and 2.24 +/- 0.27 Pg C yr(-1) for the oceans (the
both are adjusted by riverine input of CO2). For the first time the
CONTRAIL CO2 measurements were used in an inversion system to identify
the areas of greatest impact in terms of reducing flux uncertainties.
BibTeX:
@article{niwa12a,
  author = {Niwa, Yosuke and Machida, Toshinobu and Sawa, Yousuke and Matsueda, Hidekazu and Schuck, Tanja J. and Brenninkmeijer, Carl A. M. and Imasu, Ryoichi and Satoh, Masaki},
  title = {Imposing strong constraints on tropical terrestrial CO2 fluxes using passenger aircraft based measurements},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2012},
  volume = {117},
  doi = {10.1029/2012JD017474}
}
Noel S, Bramstedt K, Hilker M, Liebing P, Plieninger J, Reuter M, Rozanov A, Sioris CE, Bovensmann H and Burrows JP ({2016}), "Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {9}({4}), pp. 1485-1503.
Abstract: Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have
been derived from solar occultation measurements of the SCanning Imaging
Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The
retrieval is performed using a method called onion peeling DOAS (ONPD),
which combines an onion peeling approach with a weighting function DOAS
(differential optical absorption spectroscopy) fit in the spectral
region between 1559 and 1671 nm. By use of updated pointing information
and optimisation of the data selection as well as of the retrieval
approach, the altitude range for reasonable CH4 could be broadened from
20 to 40 km to about 17 to 45 km. Furthermore, the quality of the
derived CO2 has been assessed such that now the first stratospheric
profiles (17-45 km) of CO2 from SCIAMACHY are available. Comparisons
with independent data sets yield an estimated accuracy of the new
SCIAMACHY stratospheric profiles of about 5-10% for CH4 and 2-3% for
CO2. The accuracy of the products is currently mainly restricted by the
appearance of unexpected vertical oscillations in the derived profiles
which need further investigation. Using the improved ONPD retrieval, CH4
and CO2 stratospheric data sets covering the whole SCIAMACHY time series
(August 2002-April 2012) and the latitudinal range between about 50 and
70 degrees N have been derived. Based on these time series, CH4 and CO2
trends have been estimated. CH4 trends above about 20 km are not
significantly different from zero and the trend at 17 km is about 3 ppbv
year(-1). The derived CO2 trends show a general decrease with altitude
with values of about 1.9 ppmv year(-1) at 21 km and about 1.3 ppmv
year(-1) at 39 km. These results are in reasonable agreement with total
column trends for these gases. This shows that the new SCIAMACHY data
sets can provide valuable information about the stratosphere.
BibTeX:
@article{noel16a,
  author = {Noel, Stefan and Bramstedt, Klaus and Hilker, Michael and Liebing, Patricia and Plieninger, Johannes and Reuter, Max and Rozanov, Alexei and Sioris, Christopher E. and Bovensmann, Heinrich and Burrows, John P.},
  title = {Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2016},
  volume = {9},
  number = {4},
  pages = {1485--1503},
  doi = {10.5194/amt-9-1485-2016}
}
Novick KA, Ficklin DL, Stoy PC, Williams CA, Bohrer G, Oishi AC, Papuga SA, Blanken PD, Noormets A, Sulman BN, Scott RL, Wang L and Phillips RP ({2016}), "The increasing importance of atmospheric demand for ecosystem water and carbon fluxes", NATURE CLIMATE CHANGE., NOV, {2016}. Vol. {6}({11}), pp. 1023-1027.
Abstract: Soil moisture supply and atmospheric demand for water independently
limit-and profoundly affect-vegetation productivity and water use during
periods of hydrologic stress(1-4). Disentangling the impact of these two
drivers on ecosystem carbon and water cycling is difficult because they
are often correlated, and experimental tools for manipulating
atmospheric demand in the field are lacking. Consequently, the role of
atmospheric demand is often not adequately factored into experiments or
represented in models(5-7). Here we show that atmospheric demand limits
surface conductance and evapotranspiration to a greater extent than soil
moisture in many biomes, including mesic forests that are of particular
importance to the terrestrial carbon sink(8,9). Further, using
projections from ten general circulation models, we show that climate
change will increase the importance of atmospheric constraints to carbon
and water fluxes in all ecosystems. Consequently, atmospheric demand
will become increasingly important for vegetation function, accounting
for >70% of growing season limitation to surface conductance in mesic
temperate forests. Our results suggest that failure to consider the
limiting role of atmospheric demand in experimental designs, simulation
models and land management strategies will lead to incorrect projections
of ecosystem responses to future climate conditions.
BibTeX:
@article{novick16a,
  author = {Novick, Kimberly A. and Ficklin, Darren L. and Stoy, Paul C. and Williams, Christopher A. and Bohrer, Gil and Oishi, A. Christopher and Papuga, Shirley A. and Blanken, Peter D. and Noormets, Asko and Sulman, Benjamin N. and Scott, Russell L. and Wang, Lixin and Phillips, Richard P.},
  title = {The increasing importance of atmospheric demand for ecosystem water and carbon fluxes},
  journal = {NATURE CLIMATE CHANGE},
  year = {2016},
  volume = {6},
  number = {11},
  pages = {1023--1027},
  doi = {10.1038/NCLIMATE3114}
}
Oda T, Maksyutov S and Andres R (2018), "The Open-source Data Inventory for Anthropogenic CO2, version 2016 (ODIAC2016): a global monthly fossil fuel CO2 gridded emissions data product for tracer transport simulations and surface flux inversions", Earth System Science Data., JAN 18, 2018. Vol. {10}({1}), pp. {87-107}.
Abstract: The Open-source Data Inventory for Anthropogenic CO2 (ODIAC) is a global
high-spatial-resolution gridded emissions data product that distributes
carbon dioxide (CO2) emissions from fossil fuel combustion. The
emissions spatial distributions are estimated at a 1 x 1 km spatial
resolution over land using power plant profiles (emissions intensity and
geographical location) and satellite-observed nighttime lights. This
paper describes the year 2016 version of the ODIAC emissions data
product (ODIAC2016) and presents analyses that help guide data users,
especially for atmospheric CO2 tracer transport simulations and flux
inversion analysis. Since the original publication in 2011, we have made
modifications to our emissions modeling framework in order to deliver a
comprehensive global gridded emissions data product. Major changes from
the 2011 publication are (1) the use of emissions estimates made by the
Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge
National Laboratory (ORNL) by fuel type (solid, liquid, gas, cement
manufacturing, gas flaring, and international aviation and marine
bunkers); (2) the use of multiple spatial emissions proxies by fuel type
such as (a) nighttime light data specific to gas flaring and (b)
ship/aircraft fleet tracks; and (3) the inclusion of emissions temporal
variations. Using global fuel consumption data, we extrapolated the
CDIAC emissions estimates for the recent years and produced the
ODIAC2016 emissions data product that covers 2000-2015. Our emissions
data can be viewed as an extended version of CDIAC gridded emissions
data product, which should allow data users to impose global fossil fuel
emissions in a more comprehensive manner than the original CDIAC
product. Our new emissions modeling framework allows us to produce
future versions of the ODIAC emissions data product with a timely
update. Such capability has become more significant given the
CDIAC/ORNL's shutdown. The ODIAC data product could play an important
role in supporting carbon cycle science, especially modeling studies
with space-based CO2 data collected in near real time by ongoing carbon
observing missions such as the Japanese Greenhouse gases Observing
SATellite (GOSAT), NASA's Orbiting Carbon Observatory-2 (OCO-2), and
upcoming future missions. The ODIAC emissions data product including the
latest version of the ODIAC emissions data (ODIAC2017, 2000-2016) is
distributed from http://db.cger.nies.go. jp/dataset/ODIAC/ with a DOI
(https://doi.org/10.17595/20170411.001).
BibTeX:
@article{oda18a,
  author = {T Oda and S Maksyutov and RJ Andres},
  title = {The Open-source Data Inventory for Anthropogenic CO2, version 2016 (ODIAC2016): a global monthly fossil fuel CO2 gridded emissions data product for tracer transport simulations and surface flux inversions},
  journal = {Earth System Science Data},
  year = {2018},
  volume = {10},
  number = {1},
  pages = {87-107},
  doi = {{10.5194/essd-10-87-2018}}
}
O'Dell CW, Eldering A, Wennberg PO, Crisp D, Gunson MR, Fisher B, Frankenberg C, Kiel M, Lindqvist H, Mandrake L, Merrelli A, Natraj V, Nelson RR, Osterman GB, Payne VH, Taylor TE, Wunch D, Drouin BJ, Oyafuso F, Chang A, McDuffie J, Smyth M, Baker DF, Basu S, Chevallier F, Crowell SMR, Feng L, Palmer PI, Dubey M, Garcia OE, Griffith DWT, Hase F, Iraci LT, Kivi R, Morino I, Notholt J, Ohyama H, Petri C, Roehl CM, Sha MK, Strong K, Sussmann R, Te Y, Uchino O and Velazco VA ({2018}), "Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm", ATMOSPHERIC MEASUREMENT TECHNIQUES., DEC 11, {2018}. Vol. {11}({12}), pp. {6539-6576}.
Abstract: Since September 2014, NASA's Orbiting Carbon Observatory-2 (OCO-2)
satellite has been taking measurements of reflected solar spectra and
using them to infer atmospheric carbon dioxide levels. This work
provides details of the OCO-2 retrieval algorithm, versions 7 and 8,
used to derive the column-averaged dry air mole fraction of atmospheric
CO2 (X-CO2) for the roughly 100 000 cloud-free measurements recorded by
OCO-2 each day. The algorithm is based on the Atmospheric Carbon
Observations from Space (ACOS) algorithm which has been applied to
observations from the Greenhouse Gases Observing SATellite (GOSAT) since
2009, with modifications necessary for OCO-2. Because high accuracy,
better than 0.25 is required in order to accurately infer carbon
sources and sinks from X-CO2, significant errors and regional-scale
biases in the measurements must be minimized. We discuss efforts to
filter out poor-quality measurements, and correct the remaining
good-quality measurements to minimize regional-scale biases. Updates to
the radiance calibration and retrieval forward model in version 8 have
improved many aspects of the retrieved data products. The version 8 data
appear to have reduced regional-scale biases overall, and demonstrate a
clear improvement over the version 7 data. In particular, error variance
with respect to TCCON was reduced by 20% over land and 40% over ocean
between versions 7 and 8, and nadir and glint observations over land are
now more consistent. While this paper documents the significant
improvements in the ACOS algorithm, it will continue to evolve and
improve as the CO2 data record continues to expand.
BibTeX:
@article{odell18a,
  author = {O'Dell, Christopher W. and Eldering, Annmarie and Wennberg, Paul O. and Crisp, David and Gunson, Michael R. and Fisher, Brendan and Frankenberg, Christian and Kiel, Matthaus and Lindqvist, Hannakaisa and Mandrake, Lukas and Merrelli, Aronne and Natraj, Vijay and Nelson, Robert R. and Osterman, Gregory B. and Payne, Vivienne H. and Taylor, Thomas E. and Wunch, Debra and Drouin, Brian J. and Oyafuso, Fabiano and Chang, Albert and McDuffie, James and Smyth, Michael and Baker, David F. and Basu, Sourish and Chevallier, Frederic and Crowell, Sean M. R. and Feng, Liang and Palmer, Paul I. and Dubey, Mavendra and Garcia, Omaira E. and Griffith, David W. T. and Hase, Frank and Iraci, Laura T. and Kivi, Rigel and Morino, Isamu and Notholt, Justus and Ohyama, Hirofumi and Petri, Christof and Roehl, Coleen M. and Sha, Mahesh K. and Strong, Kimberly and Sussmann, Ralf and Te, Yao and Uchino, Osamu and Velazco, Voltaire A.},
  title = {Improved retrievals of carbon dioxide from Orbiting Carbon Observatory-2 with the version 8 ACOS algorithm},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2018},
  volume = {11},
  number = {12},
  pages = {6539-6576},
  doi = {{10.5194/amt-11-6539-2018}}
}
Ogle SM, Davis K, Lauvaux T, Schuh A, Cooley D, West TO, Heath LS, Miles NL, Richardson S, Breidt FJ, Smith JE, McCarty JL, Gurney KR, Tans P and Denning AS ({2015}), "An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data", ENVIRONMENTAL RESEARCH LETTERS., MAR, {2015}. Vol. {10}({3})
Abstract: Verifying national greenhouse gas (GHG) emissions inventories is a
critical step to ensure that reported emissions data to the United
Nations Framework Convention on Climate Change (UNFCCC) are accurate and
representative of a country's contribution to GHG concentrations in the
atmosphere. Furthermore, verifying biogenic fluxes provides a check on
estimated emissions associated with managing lands for carbon
sequestration and other activities, which often have large
uncertainties. We report here on the challenges and results associated
with a case study using atmospheric measurements of CO2 concentrations
and inverse modeling to verify nationally-reported biogenic CO2
emissions. The biogenic CO2 emissions inventory was compiled for the
Mid-Continent region of United States based on methods and data used by
the US government for reporting to the UNFCCC, along with additional
sources and sinks to produce a full carbon balance. The biogenic
emissions inventory produced an estimated flux of -408 +/- 136 TgCO(2)
for the entire study region, which was not statistically different from
the biogenic flux of -478 +/- 146 TgCO(2) that was estimated using the
atmospheric CO2 concentration data. At sub-regional scales, the spatial
density of atmospheric observations did not appear sufficient to verify
emissions in general. However, a difference between the inventory and
inversion results was found in one isolated area of West-central
Wisconsin. This part of the region is dominated by forestlands,
suggesting that further investigation may be warranted into the forest
Cstock or harvested wood product data from this portion of the study
area. The results suggest that observations of atmospheric CO2
concentration data and inverse modeling could be used to verify biogenic
emissions, and provide more confidence in biogenic GHG emissions
reporting to the UNFCCC.
BibTeX:
@article{ogle15a,
  author = {Ogle, Stephen M. and Davis, Kenneth and Lauvaux, Thomas and Schuh, Andrew and Cooley, Dan and West, Tristram O. and Heath, Linda S. and Miles, Natasha L. and Richardson, Scott and Breidt, F. Jay and Smith, James E. and McCarty, Jessica L. and Gurney, Kevin R. and Tans, Pieter and Denning, A. Scott},
  title = {An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data},
  journal = {ENVIRONMENTAL RESEARCH LETTERS},
  year = {2015},
  volume = {10},
  number = {3},
  doi = {10.1088/1748-9326/10/3/034012}
}
Palko H (2017), "Exploring Potential Sites for Salinity Gradient Renewable Energy on the North Carolina Coast and Evaluating the Potential Effects of Local Salinity Regime Variation on SAV Communities due to Reverse Electrodialysis Effluent"
BibTeX:
@phdthesis{palko17a,
  author = {Palko, Hannah},
  title = {Exploring Potential Sites for Salinity Gradient Renewable Energy on the North Carolina Coast and Evaluating the Potential Effects of Local Salinity Regime Variation on SAV Communities due to Reverse Electrodialysis Effluent},
  year = {2017},
  url = {http://search.proquest.com/openview/a19725ee830dba965021f7c25ae33a4e/1?pq-origsite=gscholar&cbl=18750&diss=y}
}
Pan Y, Chen JM, Birdsey R, McCullough K, He L and Deng F ({2011}), "Age structure and disturbance legacy of North American forests", BIOGEOSCIENCES. Vol. {8}({3}), pp. 715-732.
Abstract: Most forests of the world are recovering from a past disturbance. It is
well known that forest disturbances profoundly affect carbon stocks and
fluxes in forest ecosystems, yet it has been a great challenge to assess
disturbance impacts in estimates of forest carbon budgets. Net
sequestration or loss of CO(2) by forests after disturbance follows a
predictable pattern with forest recovery. Forest age, which is related
to time since disturbance, is a useful surrogate variable for analyses
of the impact of disturbance on forest carbon. In this study, we
compiled the first continental forest age map of North America by
combining forest inventory data, historical fire data, optical satellite
data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive
Processing System (LEDAPS) project. A companion map of the standard
deviations for age estimates was developed for quantifying uncertainty.
We discuss the significance of the disturbance legacy from the past, as
represented by current forest age structure in different regions of the
US and Canada, by analyzing the causes of disturbances from land
management and nature over centuries and at various scales. We also show
how such information can be used with inventory data for analyzing
carbon management opportunities. By combining geographic information
about forest age with estimated C dynamics by forest type, it is
possible to conduct a simple but powerful analysis of the net CO2 uptake
by forests, and the potential for increasing (or decreasing) this rate
as a result of direct human intervention in the disturbance/age status.
Finally, we describe how the forest age data can be used in large-scale
carbon modeling, both for land-based biogeochemistry models and
atmosphere-based inversion models, in order to improve the spatial
accuracy of carbon cycle simulations.
BibTeX:
@article{pan11a,
  author = {Pan, Y. and Chen, J. M. and Birdsey, R. and McCullough, K. and He, L. and Deng, F.},
  title = {Age structure and disturbance legacy of North American forests},
  journal = {BIOGEOSCIENCES},
  year = {2011},
  volume = {8},
  number = {3},
  pages = {715--732},
  doi = {10.5194/bg-8-715-2011}
}
Pandey R, Paul V, Sehgal VK, Singh MP and Bandyopadhyay K (2013), "Monitoring of CO2 exchange and carbon pools in vegetation and soil", Indian Journal of Plant Physiology. Vol. 18(2), pp. 98-117.
BibTeX:
@article{pandey13a,
  author = {Pandey, Rakesh and Paul, Vijay and Sehgal, Vinay Kumar and Singh, Madan Pal and Bandyopadhyay, Kalikinkar},
  title = {Monitoring of CO2 exchange and carbon pools in vegetation and soil},
  journal = {Indian Journal of Plant Physiology},
  year = {2013},
  volume = {18},
  number = {2},
  pages = {98--117},
  doi = {10.1007/s40502-013-0016-0}
}
Pandey S, Houweling S, Krol M, Aben I and Rockmann T ({2015}), "On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({15}), pp. 8615-8629.
Abstract: We present a method for assimilating total column CH4 : CO2 ratio
measurements from satellites for inverse modeling of CH4 and CO2 fluxes
using the variational approach. Unlike conventional approaches, in which
retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and
only the resulting CH4 is assimilated, our method assimilates the ratio
of CH4 and CO2 directly and is therefore called the ratio method. It is
a dual tracer inversion, in which surface fluxes of CH4 and CO2 are
optimized simultaneously. The optimization of CO2 fluxes turns the hard
constraint of prescribing model-derived CO2 fields into a weak
constraint on CO2, which allows us to account for uncertainties in CO2.
The method has been successfully tested in a synthetic inversion setup.
We show that the ratio method is able to reproduce assumed true CH4 and
CO2 fluxes starting from a prior, which is derived by perturbing the
true fluxes randomly. We compare the performance of the ratio method
with that of the traditional proxy approach and the use of only surface
measurements for estimating CH4 fluxes. Our results confirm that the
optimized CH4 fluxes are sensitive to the treatment of CO2, and that
hard constraints on CO2 may significantly compromise results that are
obtained for CH4. We find that the relative performance of ratio and
proxy methods have a regional dependence. The ratio method performs
better than the proxy method in regions where the CO2 fluxes are most
uncertain. However, both ratio and proxy methods perform better than the
surface-measurement-only inversion, confirming the potential of
spaceborne measurements for accurately determining fluxes of CH4 and
other greenhouse gases (GHGs).
BibTeX:
@article{pandey15a,
  author = {Pandey, S. and Houweling, S. and Krol, M. and Aben, I. and Rockmann, T.},
  title = {On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {15},
  pages = {8615--8629},
  doi = {10.5194/acp-15-8615-2015}
}
Pandey S, Houweling S, Krol M, Aben I, Chevallier F, Dlugokencky EJ, Gatti LV, Gloor E, Miller JB, Detmers R, Machida T and Rockmann T ({2016}), "Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {16}({8}), pp. 5043-5062.
Abstract: This study investigates the constraint provided by greenhouse gas
measurements from space on surface fluxes. Imperfect knowledge of the
light path through the atmosphere, arising from scattering by clouds and
aerosols, can create biases in column measurements retrieved from space.
To minimize the impact of such biases, ratios of total column retrieved
CH4 and CO2 (X-ratio) have been used. We apply the ratio inversion
method described in Pandey et al. (2015) to retrievals from the
Greenhouse Gases Observing SATellite (GOSAT). The ratio inversion method
uses the measured X-ratio as a weak constraint on CO2 fluxes. In
contrast, the more common approach of inverting proxy CH4 retrievals
(Frankenberg et al., 2005) prescribes atmospheric CO2 fields and
optimizes only CH4 fluxes.
The TM5-4DVAR (Tracer Transport Model version 5-variational data
assimilation system) inverse modeling system is used to simultaneously
optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are
compared to proxy inversions using model-derived CO2 mixing ratios
(XCO2model) from CarbonTracker and the Monitoring Atmospheric
Composition and Climate (MACC) Reanalysis CO2 product. The performance
of the inverse models is evaluated using measurements from three
aircraft measurement projects.
X-ratio and XCO2model are compared with TCCON retrievals to quantify the
relative importance of errors in these components of the proxy XCH4
retrieval (XCH4proxy). We find that the retrieval errors in X-ratio
(meanaEuro- = aEuro-0.61aEuro- are generally larger than the errors
in XCO2model (meanaEuro- = aEuro-0.24 and 0.01aEuro-% for CarbonTracker
and MACC, respectively). On the annual timescale, the CH4 fluxes from
the different satellite inversions are generally in agreement with each
other, suggesting that errors in XCO2model do not limit the overall
accuracy of the CH4 flux estimates. On the seasonal timescale, however,
larger differences are found due to uncertainties in XCO2model,
particularly over Australia and in the tropics. The ratio method stays
closer to the a priori CH4 flux in these regions, because it is capable
of simultaneously adjusting the CO2 fluxes. Over tropical South America,
comparison to independent measurements shows that CO2 fields derived
from the ratio method are less realistic than those used in the proxy
method. However, the CH4 fluxes are more realistic, because the impact
of unaccounted systematic uncertainties is more evenly distributed
between CO2 and CH4. The ratio inversion estimates an enhanced CO2
release from tropical South America during the dry season of 2010, which
is in accordance with the findings of Gatti et al. (2014) and Van der
Laan et al. (2015).
The performance of the ratio method is encouraging, because despite the
added nonlinearity due to the assimilation of X-ratio and the
significant increase in the degree of freedom by optimizing CO2 fluxes,
still consistent results are obtained with respect to other CH4
inversions..
BibTeX:
@article{pandey16a,
  author = {Pandey, Sudhanshu and Houweling, Sander and Krol, Maarten and Aben, Ilse and Chevallier, Frederic and Dlugokencky, Edward J. and Gatti, Luciana V. and Gloor, Emanuel and Miller, John B. and Detmers, Rob and Machida, Toshinobu and Rockmann, Thomas},
  title = {Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {8},
  pages = {5043--5062},
  doi = {10.5194/acp-16-5043-2016}
}
Pandey S (2017), "Advancing the use of satellites to constrain atmospheric methane fluxes". Thesis at: Utrecht University.
BibTeX:
@phdthesis{pandey17a,
  author = {Pandey, Sudhanshu},
  title = {Advancing the use of satellites to constrain atmospheric methane fluxes},
  school = {Utrecht University},
  year = {2017},
  url = {https://dspace.library.uu.nl/handle/1874/345119}
}
Pandeyl R, Paull V, Sehgals V, al Singh MP and Bandyopadhyay K (2013), "CAPACITIES AND UNCERTAINTIES IN MONITORING THE CARBON DIOXIDE FLUXES AND CARBON POOLS AT DIFFERENT SCALES IN TERRESTRIAL …", Physiology of Nutrition and Environmental Stresses on Crop Productivity.
BibTeX:
@article{pandeyl13a,
  author = {Pandeyl, Rakesh and Paull, Vijay and Sehgals, Vinay and al Singh, Madan P and Bandyopadhyay, Kalikinkar},
  title = {CAPACITIES AND UNCERTAINTIES IN MONITORING THE CARBON DIOXIDE FLUXES AND CARBON POOLS AT DIFFERENT SCALES IN TERRESTRIAL …},
  journal = {Physiology of Nutrition and Environmental Stresses on Crop Productivity},
  year = {2013}
}
Parazoo NC (2011), "Moist synoptic transport of CO₂ along midlatitude storm tracks, transport uncertainty, and implications for flux estimation". Thesis at: Colorado State University.
BibTeX:
@phdthesis{parazoo11a,
  author = {Parazoo, Nicholas C},
  title = {Moist synoptic transport of CO₂ along midlatitude storm tracks, transport uncertainty, and implications for flux estimation},
  school = {Colorado State University},
  year = {2011},
  url = {https://dspace.library.colostate.edu/handle/10217/48164}
}
Parazoo NC, Arneth A, Pugh TAM, Smith B, Steiner N, Luus K, Commane R, Benmergui J, Stofferahn E, Liu J, Roedenbeck C, Kawa R, Euskirchen E, Zona D, Arndt K, Oechel W and Miller C ({2018}), "Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing", GLOBAL CHANGE BIOLOGY., AUG, {2018}. Vol. {24}({8}), pp. {3416-3435}.
Abstract: The springtime transition to regional-scale onset of photosynthesis and
net ecosystem carbon uptake in boreal and tundra ecosystems are linked
to the soil freeze-thaw state. We present evidence from diagnostic and
inversion models constrained by satellite fluorescence and airborne CO2
from 2012 to 2014 indicating the timing and magnitude of spring carbon
uptake in Alaska correlates with landscape thaw and ecoregion. Landscape
thaw in boreal forests typically occurs in late April (DOY 111 +/- 7)
with a 29 +/- 6 day lag until photosynthetic onset. North Slope tundra
thaws 3weeks later (DOY 133 +/- 5) but experiences only a 20 +/- 5 day
lag until photosynthetic onset. These time lag differences reflect
efficient cold season adaptation in tundra shrub and the longer
dehardening period for boreal evergreens. Despite the short transition
from thaw to photosynthetic onset in tundra, synchrony of tundra
respiration with snow melt and landscape thaw delays the transition from
net carbon loss (at photosynthetic onset) to net uptake by 13 +/- 7
days, thus reducing the tundra net carbon uptake period. Two global CO2
inversions using a CASA-GFED model prior estimate earlier northern high
latitude net carbon uptake compared to our regional inversion, which we
attribute to (i) early photosynthetic-onset model prior bias, (ii)
inverse method (scaling factor+optimization window), and (iii) sparsity
of available Alaskan CO2 observations. Another global inversion with
zero prior estimates the same timing for net carbon uptake as the
regional model but smaller seasonal amplitude. The analysis of Alaskan
eddy covariance observations confirms regional scale findings for
tundra, but indicates that photosynthesis and net carbon uptake occur up
to 1 month earlier in evergreens than captured by models or CO2
inversions, with better correlation to above-freezing air temperature
than date of primary thaw. Further collection and analysis of boreal
evergreen species over multiple years and at additional subarctic flux
towers are critically needed.
BibTeX:
@article{parazoo18a,
  author = {Parazoo, Nicholas C. and Arneth, Almut and Pugh, Thomas A. M. and Smith, Ben and Steiner, Nicholas and Luus, Kristina and Commane, Roisin and Benmergui, Josh and Stofferahn, Eric and Liu, Junjie and Roedenbeck, Christian and Kawa, Randy and Euskirchen, Eugenie and Zona, Donatella and Arndt, Kyle and Oechel, Walt and Miller, Charles},
  title = {Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2018},
  volume = {24},
  number = {8},
  pages = {3416-3435},
  doi = {{10.1111/gcb.14283}}
}
Park J ({2011}), "EVIDENCE FOR OCEANIC CONTROL OF INTERANNUAL CARBON CYCLE FEEDBACKS", AMERICAN JOURNAL OF SCIENCE., JUN, {2011}. Vol. {311}({6}), pp. 485-516.
Abstract: Large-scale carbon-cycle feedbacks within Earth's climate system can be
inferred from the statistical correlation of atmospheric CO2 and other
climate observations. These statistical relationships can serve as
validation targets for global carbon-cycle models. Fourier-transform
coherence between atmospheric CO2 measured at Mauna Loa, Hawaii, and
Hadley Centre global-average temperatures changed in the late 20th
century at interannual frequencies, from a 6-month time lag to a 90
phase lag that scaled CO2 fluctuations to a time-integral of the
global-average temperature anomaly. Wavelet coherence estimates argue
that this change occurred with a recognized ocean-circulation climate
transition during the late 1970s. General features of these
CO2-temperature correlations are confirmed using global-average
temperature from other sources and atmospheric CO2 measured at other
locations, though only the Mauna Loa CO2 record is long enough to
resolve well the coherence properties before the 1970s transition. The
CO2-coherence phase for the global-average surface-air temperature time
series from NASA-GISS and the lower-troposphere temperature series from
the MSU satellite is more complex than for the Hadley-Centre dataset,
the only estimate that incorporates sea-surface temperature (SST)
observations. Near f = 0.25 cyc/year, 4-year oscillation period, the
CO2-coherence is particularly strong for the Hadley-Centre gridpoint
temperature-anomaly time series from low-latitude oceans. This suggests
that sea-surface temperature is a primary driver of the correlation, at
least for the 0.2 < f < 0.5 cyc/yr bandpass where the
El-Nino/Southern-Oscillation (ENSO) climate process dominates. Outside,
the ENSO bandpass coherence is significant between 14 long-running
GLOBALVIEW CO2-observing sites and the sea-level-pressure-based Southern
Oscillation Index (SOI) and North Atlantic Oscillation (NAO) time
series, consistent with wind stress and mixed-layer-thickness influences
on ocean-atmosphere CO2 flux, independent of temperature fluctuations.
Evidence for terrestrial biosphere influence is strongest in the leading
principal component of GLOBALVIEW CO2-variability at f = 0.25 cpy, where
a larger amplitude and a 4-month phase shift distinguish the mid- and
high-latitude Northern Hemisphere CO2 fluctuations from those of the
tropics and the Southern Hemisphere. The terrestrial signal we infer,
however, coheres more strongly with oceanic-gridpoint temperatures than
to continental-gridpoint temperatures.
BibTeX:
@article{park11a,
  author = {Park, Jeffrey},
  title = {EVIDENCE FOR OCEANIC CONTROL OF INTERANNUAL CARBON CYCLE FEEDBACKS},
  journal = {AMERICAN JOURNAL OF SCIENCE},
  year = {2011},
  volume = {311},
  number = {6},
  pages = {485--516},
  doi = {10.2475/06.2011.01}
}
Park C, Gerbig C, Newman S, Ahmadov R, Feng S, Gurney KR, Carmichael GR, Park S-Y, Lee H-W, Goulden M, Stutz J, Peischl J and Ryerson T ({2018}), "CO2 Transport, Variability, and Budget over the Southern California Air Basin Using the High-Resolution WRF-VPRM Model during the CalNex 2010 Campaign", JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY., JUN, {2018}. Vol. {57}({6}), pp. {1337-1352}.
Abstract: To study regional-scale carbon dioxide (CO2) transport, temporal
variability, and budget over the Southern California Air Basin (SoCAB)
during the California Research at the Nexus of Air Quality and Climate
Change (CalNex) 2010 campaign period, a model that couples the Weather
Research and Forecasting (WRF) Model with the Vegetation Photosynthesis
and Respiration Model (VPRM) has been used. Our numerical simulations
use anthropogenic CO2 emissions of the Hestia Project 2010 fossil-fuel
CO2 emissions data products along with optimized VPRM parameters at
``FLUXNET'' sites, for biospheric CO2 fluxes over SoCAB. The simulated
meteorological conditions have been validated with ground and aircraft
observations, as well as with background CO2 concentrations from the
coastal Palos Verdes site. The model captures the temporal pattern of
CO2 concentrations at the ground site at the California Institute of
Technology in Pasadena, but it overestimates the magnitude in early
daytime. Analysis of CO2 by wind directions reveals the overestimate is
due to advection from the south and southwest, where downtown Los
Angeles is located. The model also captures the vertical profile of CO2
concentrations along with the flight tracks. The optimized VPRM
parameters have significantly improved simulated net ecosystem exchange
at each vegetation-class site and thus the regional CO2 budget. The
total biospheric contribution ranges approximately from -24% to -20br> (daytime) of the total anthropogenic CO2 emissions during the study
period.
BibTeX:
@article{park18a,
  author = {Park, Changhyoun and Gerbig, Christoph and Newman, Sally and Ahmadov, Ravan and Feng, Sha and Gurney, Kevin R. and Carmichael, Gregory R. and Park, Soon-Young and Lee, Hwa-Woon and Goulden, Mike and Stutz, Jochen and Peischl, Jeff and Ryerson, Tom},
  title = {CO2 Transport, Variability, and Budget over the Southern California Air Basin Using the High-Resolution WRF-VPRM Model during the CalNex 2010 Campaign},
  journal = {JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY},
  year = {2018},
  volume = {57},
  number = {6},
  pages = {1337-1352},
  doi = {{10.1175/JAMC-D-17-0358.1}}
}
Parker R, Boesch H, Cogan A, Fraser A, Feng L, Palmer PI, Messerschmidt J, Deutscher N, Griffith DWT, Notholt J, Wennberg PO and Wunch D ({2011}), "Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations", GEOPHYSICAL RESEARCH LETTERS., AUG 6, {2011}. Vol. {38}
Abstract: We report new short-wave infrared (SWIR) column retrievals of
atmospheric methane (X(CH4)) from the Japanese Greenhouse Gases
Observing SATellite (GOSAT) and compare observed spatial and temporal
variations with correlative ground-based measurements from the Total
Carbon Column Observing Network (TCCON) and with the global 3-D
GEOS-Chem chemistry transport model. GOSAT X(CH4) retrievals are
compared with daily TCCON observations at six sites between April 2009
and July 2010 (Bialystok, Park Falls, Lamont, Orleans, Darwin and
Wollongong). GOSAT reproduces the site-dependent seasonal cycles as
observed by TCCON with correlations typically between 0.5 and 0.7 with
an estimated single-sounding precision between 0.4-0.8%. We find a
latitudinal-dependent difference between the X(CH4) retrievals from
GOSAT and TCCON which ranges from 17.9 ppb at the most northerly site
(Bialystok) to -14.6 ppb at the site with the lowest latitude (Darwin).
We estimate that the mean smoothing error difference included in the
GOSAT to TCCON comparisons can account for 15.7 to 17.4 ppb for the
northerly sites and for 1.1 ppb at the lowest latitude site. The GOSAT
X(CH4) retrievals agree well with the GEOS-Chem model on annual (August
2009 - July 2010) and monthly timescales, capturing over 80% of the
zonal variability. Differences between model and observed X(CH4) are
found over key source regions such as Southeast Asia and central Africa
which will be further investigated using a formal inverse model
analysis. Citation: Parker, R., et al. (2011), Methane observations from
the Greenhouse Gases Observing SATellite: Comparison to ground-based
TCCON data and model calculations, Geophys. Res. Lett., 38, L15807,
doi:10.1029/2011GL047871.
BibTeX:
@article{parker11a,
  author = {Parker, Robert and Boesch, Hartmut and Cogan, Austin and Fraser, Annemarie and Feng, Liang and Palmer, Paul I. and Messerschmidt, Janina and Deutscher, Nicholas and Griffith, David W. T. and Notholt, Justus and Wennberg, Paul O. and Wunch, Debra},
  title = {Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations},
  journal = {GEOPHYSICAL RESEARCH LETTERS},
  year = {2011},
  volume = {38},
  doi = {10.1029/2011GL047871}
}
Parker RJ, Boesch H, Byckling K, Webb AJ, Palmer PI, Feng L, Bergamaschi P, Chevallier F, Notholt J, Deutscher N, Warneke T, Hase F, Sussmann R, Kawakami S, Kivi R, Griffith DWT and Velazco V ({2015}), "Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {8}({11}), pp. 4785-4801.
Abstract: We present 5 years of GOSAT XCH4 retrieved using the ``proxy''
approach. The Proxy XCH4 data are validated against ground-based TCCON
observations and are found to be of high quality with a small bias of
4.8 ppb (similar to 0.27 and a single-sounding precision of 13.4 ppb
(similar to 0.74 . The station-to-station bias (a measure of the
relative accuracy) is found to be 4.2 ppb. For the first time the XCH4 =
XCO2 ratio component of the Proxy retrieval is validated (bias of 0.014
ppbppm 1 (similar to 0.30 , single-sounding precision of 0.033 ppbppm
1 (similar to 0.72 ).
The uncertainty relating to the model XCO2 component of the Proxy XCH4
is assessed through the use of an ensemble of XCO2 models. While each
individual XCO2 model is found to agree well with the TCCON validation
data (r = 0.94-0.97), it is not possible to select one model as the best
from our comparisons. The median XCO2 value of the ensemble has a
smaller scatter against TCCON (a standard deviation of 0.92 ppm) than
any of the individual models whilst maintaining a small bias (0.15 ppm).
This model median XCO2 is used to calculate the Proxy XCH4 with the
maximum deviation of the ensemble from the median used as an estimate of
the uncertainty.
We compare this uncertainty to the a posteriori retrieval error (which
is assumed to reduce with sqrt(N)) and find typically that the model
XCO2 uncertainty becomes significant during summer months when the a
posteriori error is at its lowest due to the increase in signal related
to increased summertime reflected sunlight.
We assess the significance of these model and retrieval uncertainties on
flux inversion by comparing the GOSAT XCH4 against modelled XCH4 from
TM5-4DVAR constrained by NOAA surface observations (MACC reanalysis
scenario S1-NOAA). We find that for the majority of regions the
differences are much larger than the estimated uncertainties. Our
findings show that useful information will be provided to the inversions
for the majority of regions in addition to that already provided by the
assimilated surface measurements.
BibTeX:
@article{parker15a,
  author = {Parker, R. J. and Boesch, H. and Byckling, K. and Webb, A. J. and Palmer, P. I. and Feng, L. and Bergamaschi, P. and Chevallier, F. and Notholt, J. and Deutscher, N. and Warneke, T. and Hase, F. and Sussmann, R. and Kawakami, S. and Kivi, R. and Griffith, D. W. T. and Velazco, V.},
  title = {Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2015},
  volume = {8},
  number = {11},
  pages = {4785--4801},
  doi = {10.5194/amt-8-4785-2015}
}
Patra PK, Crisp D, Kaiser JW, Wunch D, Saeki T, Ichii K, Sekiya T, Wennberg PO, Feist DG, Pollard DF, Griffith DWT, Velazco VA, De Maziere M, Sha MK, Roehl C, Chatterjee A and Ishijima K ({2017}), "The Orbiting Carbon Observatory (OCO-2) tracks 2-3 peta-gram increase in carbon release to the atmosphere during the 2014-2016 El Nino", SCIENTIFIC REPORTS., OCT 19, {2017}. Vol. {7}
Abstract: The powerful El Nino event of 2015-2016 - the third most intense since
the 1950s - has exerted a large impact on the Earth's natural climate
system. The column-averaged CO2 dry-air mole fraction (XCO2)
observations from satellites and ground-based networks are analyzed
together with in situ observations for the period of September 2014 to
October 2016. From the differences between satellite (OCO-2)
observations and simulations using an atmospheric chemistry-transport
model, we estimate that, relative to the mean annual fluxes for 2014,
the most recent El Nino has contributed to an excess CO2 emission from
the Earth's surface (land + ocean) to the atmosphere in the range of 2.4
+/- 0.2 PgC (1 Pg = 10(15) g) over the period of July 2015 to June 2016.
The excess CO2 flux is resulted primarily from reduction in vegetation
uptake due to drought, and to a lesser degree from increased biomass
burning. It is about the half of the CO2 flux anomaly (range: 4.4-6.7
PgC) estimated for the 1997/1998 El Nino. The annual total sink is
estimated to be 3.9 +/- 0.2 PgC for the assumed fossil fuel emission of
10.1 PgC. The major uncertainty in attribution arise from error in
anthropogenic emission trends, satellite data and atmospheric transport.
BibTeX:
@article{patra17a,
  author = {Patra, Prabir K. and Crisp, David and Kaiser, Johannes W. and Wunch, Debra and Saeki, Tazu and Ichii, Kazuhito and Sekiya, Takashi and Wennberg, Paul O. and Feist, Dietrich G. and Pollard, David F. and Griffith, David W. T. and Velazco, Voltaire A. and De Maziere, M. and Sha, Mahesh K. and Roehl, Coleen and Chatterjee, Abhishek and Ishijima, Kentaro},
  title = {The Orbiting Carbon Observatory (OCO-2) tracks 2-3 peta-gram increase in carbon release to the atmosphere during the 2014-2016 El Nino},
  journal = {SCIENTIFIC REPORTS},
  year = {2017},
  volume = {7},
  doi = {10.1038/s41598-017-13459-0}
}
Paustian K, Lehmann J, Ogle S, Reay D, Robertson GP and Smith P ({2016}), "Climate-smart soils", NATURE., APR 7, {2016}. Vol. {532}({7597}), pp. 49-57.
Abstract: Soils are integral to the function of all terrestrial ecosystems and to
food and fibre production. An overlooked aspect of soils is their
potential to mitigate greenhouse gas emissions. Although proven
practices exist, the implementation of soil-based greenhouse gas
mitigation activities are at an early stage and accurately quantifying
emissions and reductions remains a substantial challenge. Emerging
research and information technology developments provide the potential
for a broader inclusion of soils in greenhouse gas policies. Here we
highlight `state of the art' soil greenhouse gas research, summarize
mitigation practices and potentials, identify gaps in data and
understanding and suggest ways to close such gaps through new research,
technology and collaboration.
BibTeX:
@article{paustian16a,
  author = {Paustian, Keith and Lehmann, Johannes and Ogle, Stephen and Reay, David and Robertson, G. Philip and Smith, Pete},
  title = {Climate-smart soils},
  journal = {NATURE},
  year = {2016},
  volume = {532},
  number = {7597},
  pages = {49--57},
  doi = {10.1038/nature17174}
}
Peng C, Guiot J, Wu H, Jiang H and Luo Y ({2011}), "Integrating models with data in ecology and palaeoecology: advances towards a model-data fusion approach", ECOLOGY LETTERS., MAY, {2011}. Vol. {14}({5}), pp. 522-536.
Abstract: P>It is increasingly being recognized that global ecological research
requires novel methods and strategies in which to combine process-based
ecological models and data in cohesive, systematic ways. Model-data
fusion (MDF) is an emerging area of research in ecology and
palaeoecology. It provides a new quantitative approach that offers a
high level of empirical constraint over model predictions based on
observations using inverse modelling and data assimilation (DA)
techniques. Increasing demands to integrate model and data methods in
the past decade has led to MDF utilization in palaeoecology, ecology and
earth system sciences. This paper reviews key features and principles of
MDF and highlights different approaches with regards to DA. After
providing a critical evaluation of the numerous benefits of MDF and its
current applications in palaeoecology (i.e. palaeoclimatic
reconstruction, palaeovegetation and palaeocarbon storage) and ecology
(i.e. parameter and uncertainty estimation, model error identification,
remote sensing and ecological forecasting), the paper discusses method
limitations, current challenges and future research direction. In the
ongoing data-rich era of today's world, MDF could become an important
diagnostic and prognostic tool in which to improve our understanding of
ecological processes while testing ecological theory and hypotheses and
forecasting changes in ecosystem structure, function and services.
BibTeX:
@article{peng11a,
  author = {Peng, Changhui and Guiot, Joel and Wu, Haibin and Jiang, Hong and Luo, Yiqi},
  title = {Integrating models with data in ecology and palaeoecology: advances towards a model-data fusion approach},
  journal = {ECOLOGY LETTERS},
  year = {2011},
  volume = {14},
  number = {5},
  pages = {522--536},
  doi = {10.1111/j.1461-0248.2011.01603.x}
}
Peng Z, Zhang M, Kou X, Tian X and Ma X ({2015}), "A regional carbon data assimilation system and its preliminary evaluation in East Asia", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {15}({2}), pp. 1087-1104.
Abstract: In order to optimize surface CO2 fluxes at grid scales, a regional
surface CO2 flux inversion system (Carbon Flux Inversion system and
Community Multi-scale Air Quality, CFI-CMAQ) has been developed by
applying the ensemble Kalman filter (EnKF) to constrain the CO2
concentrations and applying the ensemble Kalman smoother (EnKS) to
optimize the surface CO2 fluxes. The smoothing operator is associated
with the atmospheric transport model to constitute a persistence
dynamical model to forecast the surface CO2 flux scaling factors. In
this implementation, the ``signal-to-noise'' problem can be avoided;
plus, any useful observed information achieved by the current
assimilation cycle can be transferred into the next assimilation cycle.
Thus, the surface CO2 fluxes can be optimized as a whole at the grid
scale in CFI-CMAQ. The performance of CFI-CMAQ was quantitatively
evaluated through a set of Observing System Simulation Experiments
(OSSEs) by assimilating CO2 retrievals from GOSAT (Greenhouse Gases
Observing Satellite). The results showed that the CO2 concentration
assimilation using EnKF could constrain the CO2 concentration
effectively, illustrating that the simultaneous assimilation of CO2
concentrations can provide convincing CO2 initial analysis fields for
CO2 flux inversion. In addition, the CO2 flux optimization using EnKS
demonstrated that CFI-CMAQ could, in general, reproduce true fluxes at
grid scales with acceptable bias. Two further sets of numerical
experiments were conducted to investigate the sensitivities of the
inflation factor of scaling factors and the smoother window. The results
showed that the ability of CFI-CMAQ to optimize CO2 fluxes greatly
relied on the choice of the inflation factor. However, the smoother
window had a slight influence on the optimized results. CFI-CMAQ
performed very well even with a short lag-window (e.g. 3 days).
BibTeX:
@article{peng15a,
  author = {Peng, Z. and Zhang, M. and Kou, X. and Tian, X. and Ma, X.},
  title = {A regional carbon data assimilation system and its preliminary evaluation in East Asia},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2015},
  volume = {15},
  number = {2},
  pages = {1087--1104},
  doi = {10.5194/acp-15-1087-2015}
}
Peng Z, Liu Z, Chen D and Ban J ({2017}), "Improving PM2.5 forecast over China by the joint adjustment of initial conditions and source emissions with an ensemble Kalman filter", ATMOSPHERIC CHEMISTRY AND PHYSICS., APR 13, {2017}. Vol. {17}({7}), pp. 4837-4855.
Abstract: In an attempt to improve the forecasting of atmospheric aerosols, the
ensemble square root filter algorithm was extended to simultaneously
optimize the chemical initial conditions (ICs) and emission input. The
forecast model, which was expanded by combining the Weather Research and
Forecasting with Chemistry (WRF-Chem) model and a forecast model of
emission scaling factors, generated both chemical concentration fields
and emission scaling factors. The forecast model of emission scaling
factors was developed by using the ensemble concentration ratios of the
WRF-Chem forecast chemical concentrations and also the time smoothing
operator. Hourly surface fine particulate matter (PM2.5) observations
were assimilated in this system over China from 5 to 16 October 2014. A
series of 48 h forecasts was then carried out with the optimized initial
conditions and emissions on each day at 00:00UTC and a control
experiment was performed without data assimilation. In addition, we also
performed an experiment of pure assimilation chemical ICs and the
corresponding 48 h forecasts experiment for comparison. The results
showed that the forecasts with the optimized initial conditions and
emissions typically outperformed those from the control experiment. In
the Yangtze River delta (YRD) and the Pearl River delta (PRD) regions,
large reduction of the root-mean-square errors (RMSEs) was obtained for
almost the entire 48 h forecast range attributed to assimilation. In
particular, the relative reduction in RMSE due to assimilation was about
37.5% at nighttime when WRF-Chem performed comparatively worse. In the
Beijing-Tianjin-Hebei (JJJ) region, relatively smaller improvements were
achieved in the first 24 h forecast but then no improvements were
achieved afterwards. Comparing to the forecasts with only the optimized
ICs, the forecasts with the joint adjustment were always much better
during the night in the PRD and YRD regions. However, they were very
similar during daytime in both regions. Also, they performed similarly
for almost the entire 48 h forecast range in the JJJ region.
BibTeX:
@article{peng17a,
  author = {Peng, Zhen and Liu, Zhiquan and Chen, Dan and Ban, Junmei},
  title = {Improving PM2.5 forecast over China by the joint adjustment of initial conditions and source emissions with an ensemble Kalman filter},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2017},
  volume = {17},
  number = {7},
  pages = {4837--4855},
  doi = {10.5194/acp-17-4837-2017}
}
Pérez IA, Sánchez ML, Garc\ia MÁ, Pardo N and Fernández-Duque B (2018), "The influence of meteorological variables on CO2 and CH4 trends recorded at a semi-natural station", Journal of environmental management. Vol. 209, pp. 37-45.
BibTeX:
@article{perez18a,
  author = {Pérez, Isidro A and Sánchez, M Luisa and Garc\ia, M Ángeles and Pardo, Nuria and Fernández-Duque, Beatriz},
  title = {The influence of meteorological variables on CO2 and CH4 trends recorded at a semi-natural station},
  journal = {Journal of environmental management},
  year = {2018},
  volume = {209},
  pages = {37--45}
}
Peters W, Jacobson AR, Sweeney C, Andrews AE, Conway TJ, Masarie K, Miller JB, Bruhwiler LMP, Petron G, Hirsch AI, Worthy DEJ, van der Werf GR, Randerson JT, Wennberg PO, Krol MC and Tans PP ({2007}), "An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker", PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA., NOV 27, {2007}. Vol. {104}({48}), pp. 18925-18930.
BibTeX:
@article{peters07a,
  author = {Peters, Wouter and Jacobson, Andrew R. and Sweeney, Colm and Andrews, Arlyn E. and Conway, Thomas J. and Masarie, Kenneth and Miller, John B. and Bruhwiler, Lori M. P. and Petron, Gabrielle and Hirsch, Adam I. and Worthy, Douglas E. J. and van der Werf, Guido R. and Randerson, James T. and Wennberg, Paul O. and Krol, Maarten C. and Tans, Pieter P.},
  title = {An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker},
  journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
  year = {2007},
  volume = {104},
  number = {48},
  pages = {18925--18930},
  doi = {10.1073/pnas.0708986104}
}
Peters W, Krol MC, van der Werf GR, Houweling S, Jones CD, Hughes J, Schaefer K, Masarie KA, Jacobson AR, Miller JB, Cho CH, Ramonet M, Schmidt M, Ciattaglia L, Apadula F, Helta D, Meinhardt F, di Sarra AG, Piacentino S, Sferlazzo D, Aalto T, Hatakka J, Strom J, Haszpra L, Meijer HAJ, van der Laan S, Neubert REM, Jordan A, Rodo X, Morgui JA, Vermeulen AT, Popa E, Rozanski K, Zimnoch M, Manning AC, Leuenberger M, Uglietti C, Dolman AJ, Ciais P, Heimann M and Tans PP ({2010}), "Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations", GLOBAL CHANGE BIOLOGY., APR, {2010}. Vol. {16}({4}), pp. 1317-1337.
Abstract: We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe
for the years 2001-2007. It is derived with a data assimilation that
uses a large set of atmospheric CO2 mole fraction observations (similar
to 70 000) to guide relatively simple descriptions of terrestrial and
oceanic net exchange, while fossil fuel and fire emissions are
prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a
flux inversion) for a set of 18 large ecosystems across Europe in which
prescribed climate, weather, and surface characteristics introduce finer
scale gradients. We find that the terrestrial biosphere in Europe
absorbed a net average of -165 Tg C yr-1 over the period considered.
This uptake is predominantly in non-EU countries, and is found in the
northern coniferous (-94 Tg C yr-1) and mixed forests (-30 Tg C yr-1) as
well as the forest/field complexes of eastern Europe (-85 Tg C yr-1). An
optimistic uncertainty estimate derived using three biosphere models
suggests the uptake to be in a range of -122 to -258 Tg C yr-1, while a
more conservative estimate derived from the a-posteriori covariance
estimates is -165 +/- 437 Tg C yr-1. Note, however, that uncertainties
are hard to estimate given the nature of the system and are likely to be
significantly larger than this. Interannual variability in NEE includes
a reduction in uptake due to the 2003 drought followed by 3 years of
more than average uptake. The largest anomaly of NEE occurred in 2005
concurrent with increased seasonal cycles of observed CO2. We speculate
these changes to result from the strong negative phase of the North
Atlantic Oscillation in 2005 that lead to favorable summer growth
conditions, and altered horizontal and vertical mixing in the
atmosphere. All our results are available through
http://www.carbontracker.eu.
BibTeX:
@article{peters10a,
  author = {Peters, W. and Krol, M. C. and van der Werf, G. R. and Houweling, S. and Jones, C. D. and Hughes, J. and Schaefer, K. and Masarie, K. A. and Jacobson, A. R. and Miller, J. B. and Cho, C. H. and Ramonet, M. and Schmidt, M. and Ciattaglia, L. and Apadula, F. and Helta, D. and Meinhardt, F. and di Sarra, A. G. and Piacentino, S. and Sferlazzo, D. and Aalto, T. and Hatakka, J. and Strom, J. and Haszpra, L. and Meijer, H. A. J. and van der Laan, S. and Neubert, R. E. M. and Jordan, A. and Rodo, X. and Morgui, J. -A. and Vermeulen, A. T. and Popa, E. and Rozanski, K. and Zimnoch, M. and Manning, A. C. and Leuenberger, M. and Uglietti, C. and Dolman, A. J. and Ciais, P. and Heimann, M. and Tans, P. P.},
  title = {Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations},
  journal = {GLOBAL CHANGE BIOLOGY},
  year = {2010},
  volume = {16},
  number = {4},
  pages = {1317--1337},
  doi = {10.1111/j.1365-2486.2009.02078.x}
}
Peters CN, Bennartz R and Hornberger GM ({2017}), "Satellite-derived methane emissions from inundation in Bangladesh", JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES., MAY, {2017}. Vol. {122}({5}), pp. 1137-1155.
Abstract: The uncertainty in methane (CH4) source strength of rice fields and
wetlands is particularly high in South Asia CH4 budgets. We used
satellite observations of CH4 column mixing ratios from Atmospheric
Infrared Sounder (AIRS), Scanning Imaging Absorption Spectrometer for
Atmospheric Chartography (SCIAMACHY), and Greenhouse Gases Observing
Satellite (GOSAT) to estimate the contribution of Bangladesh emissions
to atmospheric CH4 concentrations. Using satellite-derived inundation
area as a proxy for source area, we developed a simple inverse advection
model that estimates average annual CH4 surface fluxes to be 4, 9, and
19mgCH(4)m(-2)h(-1) in AIRS, SCIAMACHY, and GOSAT, respectively. Despite
this variability, our flux estimates varied over a significantly
narrower range than reported values for CH4 surface fluxes from a survey
of 32 studies reporting ground-based observations between 0 and
260mgCH(4)m(-2)h(-1). Upscaling our satellite-derived surface flux
estimates, we estimated total annual CH4 emissions for Bangladesh to be
1.33.2, 1.82.0, 3.11.6Tgyr(-1), depending on the satellite. Our
estimates of total emissions are in line with the median of total
emission values for Bangladesh reported in earlier studies.
Plain Language Summary The extent of methane emissions from flooded
areas, such as wetlands and rice paddies, is not well understood,
particularly in South Asia. This study uses satellite observations of
atmospheric methane and flooding to explore seasonal fluctuation in
methane emissions from Bangladesh. Our findings suggest methane
emissions similar to previously thought.
BibTeX:
@article{peters17a,
  author = {Peters, C. N. and Bennartz, R. and Hornberger, G. M.},
  title = {Satellite-derived methane emissions from inundation in Bangladesh},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
  year = {2017},
  volume = {122},
  number = {5},
  pages = {1137--1155},
  doi = {10.1002/2016JG003740}
}
Peters W, van der Velde IR, van Schaik E, Miller JB, Ciais P, Duarte HF, van der Laan-Luijkx IT, van der Molen MK, Scholze M, Schaefer K, Vidale PL, Verhoef A, Wårlind D, Zhu D, Tans PP, Vaughn B and White JWC (2018), "Increased water-use efficiency and reduced CO 2 uptake by plants during droughts at a continental scale", NATURE GEOSCIENCE. Vol. 11, pp. 744-748.
BibTeX:
@article{peters18a,
  author = {Peters, Wouter and van der Velde, Ivar R. and van Schaik, Erik and Miller, John B. and Ciais, Philippe and Duarte, Henrique F. and van der Laan-Luijkx, Ingrid T. and van der Molen, Michiel K. and Scholze, Marko and Schaefer, Kevin and Vidale, Pier Luigi and Verhoef, Anne and Wårlind, David and Zhu, Dan and Tans, Pieter P. and Vaughn, Bruce and White, James W. C.},
  title = {Increased water-use efficiency and reduced CO 2 uptake by plants during droughts at a continental scale},
  journal = {NATURE GEOSCIENCE},
  year = {2018},
  volume = {11},
  pages = {744-748},
  url = {https://www.nature.com/articles/s41561-018-0212-7}
}
Peylin P, Law RM, Gurney KR, Chevallier F, Jacobson AR, Maki T, Niwa Y, Patra PK, Peters W, Rayner PJ, Roedenbeck C, van der Laan-Luijkx IT and Zhang X ({2013}), "Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions", BIOGEOSCIENCES. Vol. {10}({10}), pp. 6699-6720.
Abstract: Atmospheric CO2 inversions estimate surface carbon fluxes from an
optimal fit to atmospheric CO2 measurements, usually including prior
constraints on the flux estimates. Eleven sets of carbon flux estimates
are compared, generated by different inversions systems that vary in
their inversions methods, choice of atmospheric data, transport model
and prior information. The inversions were run for at least 5 yr in the
period between 1990 and 2010. Mean fluxes for 2001-2004, seasonal
cycles, interannual variability and trends are compared for the tropics
and northern and southern extra-tropics, and separately for land and
ocean. Some continental/basin-scale subdivisions are also considered
where the atmospheric network is denser. Four-year mean fluxes are
reasonably consistent across inversions at global/latitudinal scale,
with a large total (land plus ocean) carbon uptake in the north (-3.4 Pg
C yr(-1) (+/- 0.5 Pg C yr(-1) standard deviation), with slightly more
uptake over land than over ocean), a significant although more variable
source over the tropics (1.6 +/- 0.9 Pg C yr(-1)) and a compensatory
sink of similar magnitude in the south (-1.4 +/- 0.5 Pg C yr(-1))
corresponding mainly to an ocean sink. Largest differences across
inversions occur in the balance between tropical land sources and
southern land sinks. Interannual variability (IAV) in carbon fluxes is
larger for land than ocean regions (standard deviation around 1.06
versus 0.33 Pg C yr(-1) for the 1996-2007 period), with much higher
consistency among the inversions for the land. While the tropical land
explains most of the IAV (standard deviation similar to 0.65 Pg C
yr(-1)), the northern and southern land also contribute (standard
deviation similar to 0.39 Pg C yr(-1)). Most inversions tend to indicate
an increase of the northern land carbon uptake from late 1990s to 2008
(around 0.1 Pg C yr(-1)), predominantly in North Asia. The mean seasonal
cycle appears to be well constrained by the atmospheric data over the
northern land (at the continental scale), but still highly dependent on
the prior flux seasonality over the ocean. Finally we provide
recommendations to interpret the regional fluxes, along with the
uncertainty estimates.
BibTeX:
@article{peylin13a,
  author = {Peylin, P. and Law, R. M. and Gurney, K. R. and Chevallier, F. and Jacobson, A. R. and Maki, T. and Niwa, Y. and Patra, P. K. and Peters, W. and Rayner, P. J. and Roedenbeck, C. and van der Laan-Luijkx, I. T. and Zhang, X.},
  title = {Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions},
  journal = {BIOGEOSCIENCES},
  year = {2013},
  volume = {10},
  number = {10},
  pages = {6699--6720},
  doi = {10.5194/bg-10-6699-2013}
}
Piao SL, Ito A, Li SG, Huang Y, Ciais P, Wang XH, Peng SS, Nan HJ, Zhao C, Ahlstrom A, Andres RJ, Chevallier F, Fang JY, Hartmann J, Huntingford C, Jeong S, Levis S, Levy PE, Li JS, Lomas MR, Mao JF, Mayorga E, Mohammat A, Muraoka H, Peng CH, Peylin P, Poulter B, Shen ZH, Shi X, Sitch S, Tao S, Tian HQ, Wu XP, Xu M, Yu GR, Viovy N, Zaehle S, Zeng N and Zhu B ({2012}), "The carbon budget of terrestrial ecosystems in East Asia over the last two decades", BIOGEOSCIENCES. Vol. {9}({9}), pp. 3571-3586.
Abstract: This REgional Carbon Cycle Assessment and Processes regional study
provides a synthesis of the carbon balance of terrestrial ecosystems in
East Asia, a region comprised of China, Japan, North and South Korea,
and Mongolia. We estimate the current terrestrial carbon balance of East
Asia and its driving mechanisms during 1990-2009 using three different
approaches: inventories combined with satellite greenness measurements,
terrestrial ecosystem carbon cycle models and atmospheric inversion
models. The magnitudes of East Asia's terrestrial carbon sink from these
three approaches are comparable: -0.293 +/- 0.033 PgC yr(-1) from
inventory-remote sensing model-data fusion approach, -0.413 +/- 0.141
PgC yr(-1)(not considering biofuel emissions) or -0.224 +/- 0.141 PgC
yr(-1) (considering biofuel emissions) for carbon cycle models, and
-0.270 +/- 0.507 PgC yr(-1) for atmospheric inverse models. Here and in
the following, the numbers behind +/- signs are standard deviations. The
ensemble of ecosystem modeling based analyses further suggests that at
the regional scale, climate change and rising atmospheric CO2 together
resulted in a carbon sink of -0.289 +/- 0.135 PgC yr(-1), while land-use
change and nitrogen deposition had a contribution of -0.013 +/- 0.029
PgC yr(-1) and -0.107 +/- 0.025 PgC yr(-1), respectively. Although the
magnitude of climate change effects on the carbon balance varies among
different models, all models agree that in response to climate change
alone, southern China experienced an increase in carbon storage from
1990 to 2009, while northern East Asia including Mongolia and north
China showed a decrease in carbon storage. Overall, our results suggest
that about 13-27% of East Asia's CO2 emissions from fossil fuel burning
have been offset by carbon accumulation in its terrestrial territory
over the period from 1990 to 2009. The underlying mechanisms of carbon
sink over East Asia still remain largely uncertain, given the diversity
and intensity of land management processes, and the regional conjunction
of many drivers such as nutrient deposition, climate, atmospheric
pollution and CO2 changes, which cannot be considered as independent for
their effects on carbon storage.
BibTeX:
@article{piao12a,
  author = {Piao, S. L. and Ito, A. and Li, S. G. and Huang, Y. and Ciais, P. and Wang, X. H. and Peng, S. S. and Nan, H. J. and Zhao, C. and Ahlstrom, A. and Andres, R. J. and Chevallier, F. and Fang, J. Y. and Hartmann, J. and Huntingford, C. and Jeong, S. and Levis, S. and Levy, P. E. and Li, J. S. and Lomas, M. R. and Mao, J. F. and Mayorga, E. and Mohammat, A. and Muraoka, H. and Peng, C. H. and Peylin, P. and Poulter, B. and Shen, Z. H. and Shi, X. and Sitch, S. and Tao, S. and Tian, H. Q. and Wu, X. P. and Xu, M. and Yu, G. R. and Viovy, N. and Zaehle, S. and Zeng, N. and Zhu, B.},
  title = {The carbon budget of terrestrial ecosystems in East Asia over the last two decades},
  journal = {BIOGEOSCIENCES},
  year = {2012},
  volume = {9},
  number = {9},
  pages = {3571--3586},
  doi = {10.5194/bg-9-3571-2012}
}
Pickett-Heaps CA, Rayner PJ, Law RM, Ciais P, Patra PK, Bousquet P, Peylin P, Maksyutov S, Marshall J, Roedenbeck C, Langenfelds RL, Steele LP, Francey RJ, Tans P and Sweeney C ({2011}), "Atmospheric CO2 inversion validation using vertical profile measurements: Analysis of four independent inversion models", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., JUN 25, {2011}. Vol. {116}
Abstract: We present the results of a validation of atmospheric inversions of CO2
fluxes using four transport models. Each inversion uses data primarily
from surface stations, combined with an atmospheric transport model, to
estimate surface fluxes. The validation (or model evaluation) consists
of running these optimized fluxes through the forward model and
comparing the simulated concentrations with airborne concentration
measurements. We focus on profiles from Cape Grim, Tasmania, and Carr,
Colorado, while using other profile sites to test the generality of the
comparison. Fits to the profiles are generally worse than to the surface
data from the inversions and worse than the expected model-data
mismatch. Thus inversion estimates are generally not consistent with the
profile measurements. The TM3 model does better by some measures than
the other three models. Models perform better over Tasmania than
Colorado, and other profile sites bear out a general improvement from
north to south and from continental to marine locations. There are also
errors in the interannual variability of the fit, consistent in time and
common across models. This suggests real variations in sources visible
to the profile but not the surface measurements.
BibTeX:
@article{pickett-heaps11a,
  author = {Pickett-Heaps, C. A. and Rayner, P. J. and Law, R. M. and Ciais, P. and Patra, P. K. and Bousquet, P. and Peylin, P. and Maksyutov, S. and Marshall, J. and Roedenbeck, C. and Langenfelds, R. L. and Steele, L. P. and Francey, R. J. and Tans, P. and Sweeney, C.},
  title = {Atmospheric CO2 inversion validation using vertical profile measurements: Analysis of four independent inversion models},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JD014887}
}
Pillai D, Gerbig C, Marshall J, Ahmadov R, Kretschmer R, Koch T and Karstens U ({2010}), "High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {10}({1}), pp. 83-94.
Abstract: Satellite retrievals for column CO2 with better spatial and temporal
sampling are expected to improve the current surface flux estimates of
CO2 via inverse techniques. However, the spatial scale mismatch between
remotely sensed CO2 and current generation inverse models can induce
representation errors, which can cause systematic biases in flux
estimates. This study is focused on estimating these representation
errors associated with utilization of satellite measurements in global
models with a horizontal resolution of about 1 degree or less. For this
we used simulated CO2 from the high resolution modeling framework
WRF-VPRM, which links CO2 fluxes from a diagnostic biosphere model to a
weather forecasting model at 10x10 km(2) horizontal resolution. Sub-grid
variability of column averaged CO2, i.e. the variability not resolved by
global models, reached up to 1.2 ppm with a median value of 0.4 ppm.
Statistical analysis of the simulation results indicate that orography
plays an important role. Using sub-grid variability of orography and CO2
fluxes as well as resolved mixing ratio of CO2, a linear model can be
formulated that could explain about 50% of the spatial patterns in the
systematic (bias or correlated error) component of representation error
in column and near-surface CO2 during day- and night-times. These
findings give hints for a parameterization of representation error which
would allow for the representation error to taken into account in
inverse models or data assimilation systems.
BibTeX:
@article{pillai10a,
  author = {Pillai, D. and Gerbig, C. and Marshall, J. and Ahmadov, R. and Kretschmer, R. and Koch, T. and Karstens, U.},
  title = {High resolution modeling of CO2 over Europe: implications for representation errors of satellite retrievals},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2010},
  volume = {10},
  number = {1},
  pages = {83--94},
  doi = {10.5194/acp-10-83-2010}
}
Pilon L, Berberoglu H and Kandilian R ({2011}), "Radiation transfer in photobiological carbon dioxide fixation and fuel production by microalgae", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2011}. Vol. {112}({17}), pp. 2639-2660.
Abstract: Solar radiation is the energy source driving the metabolic activity of
microorganisms able to photobiologically fixate carbon dioxide and
convert solar energy into biofuels. Thus, careful radiation transfer
analysis must be conducted in order to design and operate efficient
photobioreactors. This review paper first introduces light harvesting
mechanisms used by microorganisms as well as photosynthesis and
photobiological fuel production. It then provides a thorough and
critical review of both experimental and modeling efforts focusing on
radiation transfer in microalgae suspension. Experimental methods to
determine the radiation characteristics of microalgae are presented.
Methods for solving the radiation transfer equation in photobioreactors
with or without bubbles are also discussed. Sample measurements and
numerical solutions are provided. Finally, novel strategies for
achieving optimum light delivery and maximizing sunlight utilization in
photobioreactors are discussed including genetic engineering of
microorganisms with truncated chlorophyll antenna. (C) 2011 Elsevier
Ltd. All rights reserved.
BibTeX:
@article{pilon11a,
  author = {Pilon, Laurent and Berberoglu, Halil and Kandilian, Razmig},
  title = {Radiation transfer in photobiological carbon dioxide fixation and fuel production by microalgae},
  journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
  year = {2011},
  volume = {112},
  number = {17},
  pages = {2639--2660},
  doi = {10.1016/j.jqsrt.2011.07.004}
}
Pino D, Kaikkonen JP and de Arellano JV-G ({2013}), "Quantifying the uncertainties of advection and boundary layer dynamics on the diurnal carbon dioxide budget", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., AUG 27, {2013}. Vol. {118}({16}), pp. 9376-9392.
Abstract: We investigate the uncertainties in the carbon dioxide (CO2) mixing
ratio and inferred surface flux associated with boundary layer processes
and advection by using mixed-layer theory. By extending the previous
analysis presented by Pino et al. (2012), new analytical expressions are
derived to quantify the uncertainty of CO2 mixing ratio or surface flux
associated to, among others, boundary layer depth, early morning CO2
mixing ratio at the mixed layer or at the free atmosphere; or CO2
advection. We identify and calculate two sorts of uncertainties
associated to the CO2 mixing ratio and surface flux: instantaneous and
past (due to advection). The numerical experiments are guided and
constrained by meteorological and CO2 observations taken at the Cabauw
213 m tower. We select 2 days (25 September 2003 and 12 March 2004) with
a well-defined convective boundary layer but different CO2 advection
contributions. Our sensitivity analysis shows that uncertainty of the
CO2 advection in the boundary layer due to instantaneous uncertainties
represents at 1600 LT on 12 March 2004 a contribution of 2ppm and 0.072
mg m(-2)s(-1) in the uncertainty of the CO2 mixing ratio and inferred
surface flux, respectively. Taking into account that the monthly
averaged minimum CO2 surface flux for March 2004 was -0.55 mg
m(-2)s(-1), the error on the surface flux is on the order of 10%. By
including CO2 advection in the analytical expressions, we demonstrate
that the uncertainty of the CO2 mixing ratio or surface flux also
depends on the past uncertainties of the boundary layer depth.
BibTeX:
@article{pino13a,
  author = {Pino, D. and Kaikkonen, J. -P. and de Arellano, J. Vila-Guerau},
  title = {Quantifying the uncertainties of advection and boundary layer dynamics on the diurnal carbon dioxide budget},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2013},
  volume = {118},
  number = {16},
  pages = {9376--9392},
  doi = {10.1002/jgrd.50677}
}
Polavarapu SM, Neish M, Tanguay M, Girard C, de Grandpre J, Semeniuk K, Gravel S, Ren S, Roche S, Chan D and Strong K ({2016}), "Greenhouse gas simulations with a coupled meteorological and transport model: the predictability of CO2", ATMOSPHERIC CHEMISTRY AND PHYSICS., SEP 26, {2016}. Vol. {16}({18}), pp. 12005-12038.
Abstract: A new model for greenhouse gas transport has been developed based on
Environment and Climate Change Canada's operational weather and
environmental prediction models. When provided with realistic posterior
fluxes for CO2, the CO2 simulations compare well to NOAA's
Carbon-Tracker fields and to near-surface continuous measurements,
columns from the Total Carbon Column Observing Network (TCCON) and NOAA
aircraft profiles. This coupled meteorological and tracer transport
model is used to study the predictability of CO2. Predictability
concerns the quantification of model forecast errors and thus of
transport model errors. CO2 predictions are used to compute model-data
mismatches when solving flux inversion problems and the quality of such
predictions is a major concern. Here, the loss of meteorological
predictability due to uncertain meteorological initial conditions is
shown to impact CO2 predictability. The predictability of CO2 is shorter
than that of the temperature field and increases near the surface and in
the lower stratosphere. When broken down into spatial scales, CO2
predictability at the very largest scales is mainly due to surface
fluxes but there is also some sensitivity to the land and ocean surface
forcing of meteorological fields. The predictability due to the land and
ocean surface is most evident in boreal summer when biospheric uptake
produces large spatial gradients in the CO2 field. This is a newly
identified source of uncertainty in CO2 predictions but it is expected
to be much less significant than uncertainties in fluxes. However, it
serves as an upper limit for the more important source of transport
error and loss of predictability, which is due to uncertain
meteorological analyses. By isolating this component of transport error,
it is demonstrated that CO2 can only be defined on large spatial scales
due to the presence of meteorological uncertainty. Thus, for a given
model, there is a spatial scale below which fluxes cannot be inferred
simply due to the fact that meteorological analyses are imperfect. These
unresolved spatial scales correspond to small scales near the surface
but increase with altitude. By isolating other components of transport
error, the largest or limiting error can be identified. For example, a
model error due to the lack of convective tracer transport was found to
impact transport error on the very largest (wavenumbers less than 5)
spatial scales. Thus for wavenumbers greater than 5, transport model
error due to meteorological analysis uncertainty is more important for
our model than the lack of convective tracer transport.
BibTeX:
@article{polavarapu16a,
  author = {Polavarapu, Saroja M. and Neish, Michael and Tanguay, Monique and Girard, Claude and de Grandpre, Jean and Semeniuk, Kirill and Gravel, Sylvie and Ren, Shuzhan and Roche, Sebastien and Chan, Douglas and Strong, Kimberly},
  title = {Greenhouse gas simulations with a coupled meteorological and transport model: the predictability of CO2},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2016},
  volume = {16},
  number = {18},
  pages = {12005--12038},
  doi = {10.5194/acp-16-12005-2016}
}
Polavarapu SM, Deng F, Byrne B, Jones DBA and Neish M ({2018}), "A comparison of posterior atmospheric CO2 adjustments obtained from in situ and GOSAT constrained flux inversions", ATMOSPHERIC CHEMISTRY AND PHYSICS., AUG 22, {2018}. Vol. {18}({16}), pp. {12011-12044}.
Abstract: Posterior fluxes obtained from inverse modelling are difficult to verify
because there is no dense network of flux measurements available to
evaluate estimates against. Here we present a new diagnostic to evaluate
structures in posterior fluxes. First, we simulate the change in
atmospheric CO2 fields between posterior and prior fluxes, referred to
as the posterior atmospheric adjustments due to updated fluxes (PAAFs).
Second, we calculate the uncertainty in atmospheric CO2 fields due
solely to uncertainty in the meteorological fields, referred to as the
posterior atmospheric adjustments due to imperfect meteorology (PAAMs).
We argue that PAAF can only be considered robust if it exceeds PAAM,
that is, the changes in atmospheric CO2 between the posterior and prior
fluxes should at least exceed atmospheric CO2 changes arising from
imperfect meteorology. This diagnostic is applied to two CO2 flux
inversions: one which assimilates observations from the in situ CO2
network and the other which assimilates observations from the Greenhouse
Gases Observing SATellite (GOSAT). On the global scale, PAAF in the
troposphere reflects northern extratropical fluxes, whereas
stratospheric adjustments primarily reflect tropical fluxes. In general,
larger spatiotemporal variations in PAAF are obtained for the GOSAT
inversion than for the in situ inversion. Zonal standard deviations of
the PAAF exceed the PAAM through most of the year when GOSAT
observations are used, but the minimum value is exceeded only in boreal
summer when in situ observations are used. Zonal spatial structures in
GOSAT-based PAAF exceed PAAM throughout the year in the tropics and
through most of the year in the northern extratropics, suggesting GOSAT
flux inversions can constrain zonal asymmetries in fluxes. However, we
cannot discount the possibility that these structures are influenced by
biases in GOSAT retrievals. Verification of such spatial structures will
require a dense network of independent observations. Because PAAF
depends on the choice of prior fluxes, the comparison with PAAM is
system dependent and thus can be used to monitor a given assimilation
system's behaviour.
BibTeX:
@article{polavarapu18a,
  author = {Polavarapu, Saroja M. and Deng, Feng and Byrne, Brendan and Jones, Dylan B. A. and Neish, Michael},
  title = {A comparison of posterior atmospheric CO2 adjustments obtained from in situ and GOSAT constrained flux inversions},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2018},
  volume = {18},
  number = {16},
  pages = {12011-12044}
}
Pradhan R, Goroshi S and Singh RP ({2014}), "SPATIAL AND SEASONAL CHARACTERIZATION OF TERRESTRIAL BIOSPHERIC CARBON FLUX OVER INDIA USING GOSAT DATA", In ISPRS TECHNICAL COMMISSION VIII SYMPOSIUM. Vol. {40-8}, pp. 617-621.
Abstract: Carbon plays a crucial role in determining the ecosystem balance and
slight changes in its concentration in the atmosphere can have
significant impacts. The launch of JAXA's GOSAT (Greenhouse gases
Observing SATellite) in 2009 has started a new era of high accuracy CO2
concentration and flux measurements from space borne sensors. This paper
reports the spatial and temporal variability of terrestrial biospheric
carbon fluxes over the agro-climatic zones of India derived using GOSAT
data for the period June 2009 to October 2011. The country averaged
biospheric carbon flux varied from -0.47 (October) to 0.37 (April) gC
m(-2) day(-1). Maximum variability in fluxes was observed for the
North-Eastern region (-2.18 to + 1.38 gC m(-2) day(-1)) whereas the dry
region of Rajasthan showed extremely low values (-0.1 to + 0.1 gC m(-2)
day(-1)). The temporal variation in flux values was compared to averaged
NDVI for each zone and indicated that growing season corresponds to more
sequestration of carbon from the atmosphere. We compared GOSAT derived
biospheric flux with Carbon Tracker (CT) data and observed that the two
values show good agreement for all months except June and July. This
study provides new estimates of biospheric carbon flux using satellite
data driven models to better understand the carbon dynamics associated
with terrestrial biosphere over India.
BibTeX:
@inproceedings{pradhan14a,
  author = {Pradhan, Rohit and Goroshi, Sheshakumar and Singh, Raghavendra P.},
  editor = {Dadhwal, VK and Diwakar, PG and Seshasai, MVR and Raju, PLN and Hakeem, A},
  title = {SPATIAL AND SEASONAL CHARACTERIZATION OF TERRESTRIAL BIOSPHERIC CARBON FLUX OVER INDIA USING GOSAT DATA},
  booktitle = {ISPRS TECHNICAL COMMISSION VIII SYMPOSIUM},
  year = {2014},
  volume = {40-8},
  pages = {617--621},
  note = {ISPRS Technical Commission VIII Symposium, Hyderabad, INDIA, DEC 09-12, 2014},
  doi = {10.5194/isprsarchives-XL-8-617-2014}
}
Pu J, Xu H, Kang L and Ma Q (2011), "Characteristics of Atmopsheric CO2 Concentration and Variation of Carbon Source & Sink at Lin'an Regional Background Station", Environmental Science. Vol. 32(8)
BibTeX:
@article{pu11a,
  author = {Pu, Jingjiao and Xu, Honghui and Kang, Lili and Ma, Qianli},
  title = {Characteristics of Atmopsheric CO2 Concentration and Variation of Carbon Source & Sink at Lin'an Regional Background Station},
  journal = {Environmental Science},
  year = {2011},
  volume = {32},
  number = {8}
}
Le Quéré C, Canadell JG, Ciais P, Dhakal S, Patwardhan A, Raupach MR and Young OR (2010), "An International Carbon Office to assist policy-based science", Current Opinion in Environmental Sustainability. Vol. 2(4), pp. 297-300.
BibTeX:
@article{quere10a,
  author = {Le Quéré, Corinne and Canadell, Josep G and Ciais, Philippe and Dhakal, Shobhakar and Patwardhan, Anand and Raupach, Michael R and Young, Oran R},
  title = {An International Carbon Office to assist policy-based science},
  journal = {Current Opinion in Environmental Sustainability},
  year = {2010},
  volume = {2},
  number = {4},
  pages = {297--300}
}
Raczka BM, Davis KJ, Huntzinger D, Neilson RP, Poulter B, Richardson AD, Xiao J, Baker I, Ciais P, Keenan TF, Law B, Post WM, Ricciuto D, Schaefer K, Tian H, Tomelleri E, Verbeeck H and Viovy N ({2013}), "Evaluation of continental carbon cycle simulations with North American flux tower observations", ECOLOGICAL MONOGRAPHS., NOV, {2013}. Vol. {83}({4}), pp. 531-556.
Abstract: Terrestrial biosphere models can help identify physical processes that
control carbon dynamics, including land-atmosphere CO2 fluxes, and have
great potential to predict the terrestrial ecosystem response to
changing climate. The skill of models that provide continental-scale
carbon flux estimates, however, remains largely untested. This paper
evaluates the performance of continental-scale flux estimates from 17
models against observations from 36 North American flux towers. Fluxes
extracted from regional model simulations were compared with co-located
flux tower observations at monthly and annual time increments.
Site-level model simulations were used to help interpret sources of the
mismatch between the regional simulations and site-based observations.
On average, the regional model runs overestimated the annual gross
primary productivity (5 and total respiration (15, and they
significantly underestimated the annual net carbon uptake (64 during
the time period 2000-2005. Comparison with site-level simulations
implicated choices specific to regional model simulations as
contributors to the gross flux biases, but not the net carbon uptake
bias. The models performed the best at simulating carbon exchange at
deciduous broadleaf sites, likely because a number of models used
prescribed phenology to simulate seasonal fluxes. The models did not
perform as well for crop, grass, and evergreen sites. The regional
models matched the observations most closely in terms of seasonal
correlation and seasonal magnitude of variation, but they have very
little skill at interannual correlation and minimal skill at interannual
magnitude of variability. The comparison of site vs. regional-level
model runs demonstrated that (1) the interannual correlation is higher
for site-level model runs, but the skill remains low; and (2) the
underestimation of year-to-year variability for all fluxes is an
inherent weakness of the models. The best-performing regional models
that did not use flux tower calibration were CLM-CN, CASA-GFEDv2, and
SIB3.1. Two flux tower calibrated, empirical models, EC-MOD and MOD17
broken vertical bar, performed as well as the best process-based models.
This suggests that (1) empirical, calibrated models can perform as well
as complex, process-based models and (2) combining process-based model
structure with relevant constraining data could significantly improve
model performance.
BibTeX:
@article{raczka13a,
  author = {Raczka, Brett M. and Davis, Kenneth J. and Huntzinger, Deborah and Neilson, Ronald P. and Poulter, Benjamin and Richardson, Andrew D. and Xiao, Jingfeng and Baker, Ian and Ciais, Philippe and Keenan, Trevor F. and Law, Beverly and Post, Wilfred M. and Ricciuto, Daniel and Schaefer, Kevin and Tian, Hanqin and Tomelleri, Enrico and Verbeeck, Hans and Viovy, Nicolas},
  title = {Evaluation of continental carbon cycle simulations with North American flux tower observations},
  journal = {ECOLOGICAL MONOGRAPHS},
  year = {2013},
  volume = {83},
  number = {4},
  pages = {531--556},
  doi = {10.1890/12-0893.1}
}
Rajan N, Maas SJ and Cui S ({2013}), "Extreme Drought Effects on Carbon Dynamics of a Semiarid Pasture", AGRONOMY JOURNAL., NOV-DEC, {2013}. Vol. {105}({6}), pp. 1749-1760.
Abstract: Environmental and management factors are critical in determining the C
source or sink status of agroecosystems. Information on the C dynamics
of an ecosystem from source to sink and vice versa are critical in
determining the role of that ecosystem in regional and global C
balances. We investigated the impact of the 2011 mega-drought on
seasonal changes in net CO2 exchange of a WW-B. Dahl Old World bluestem
[Bothriochloa bladhii (Retz) S.T. Blake] pasture in the Texas High
Plains and compared the results with those from 2010, a hydrologically
wet year. Carbon dioxide flux between the vegetation and atmosphere was
measured using an eddy covariance flux tower. Our results indicate that
net ecosystem exchange, ecosystem respiration, and gross primary
production for this agroecosystem were strongly affected by
environmental variables and grazing. During the period of measurement in
2010 (Days of the Year 152-365), the pasture accumulated 164 g C m(-2)
and was a net C sink. During the same period in 2011, the severe drought
changed the dynamics of the pasture from a C sink to a source, with a
net cumulative loss of 142 g C m(-2). Ecosystem respiration was an
exponential function of soil temperature in both years. When extreme
water-limiting days were excluded, the exponential model explained 90br> of the variation in ecosystem respiration in 2011 and 92% of the
variation in ecosystem respiration in 2010. Incorporating the results
from our study with ecosystem models can improve our understanding of
the contributions of managed pastures to regional C balances.
BibTeX:
@article{rajan13a,
  author = {Rajan, Nithya and Maas, Stephan J. and Cui, Song},
  title = {Extreme Drought Effects on Carbon Dynamics of a Semiarid Pasture},
  journal = {AGRONOMY JOURNAL},
  year = {2013},
  volume = {105},
  number = {6},
  pages = {1749--1760},
  doi = {10.2134/agronj2013.0112}
}
Reed ZD, Sperling B, van Zee RD, Whetstone JR, Gillis KA and Hodges JT ({2014}), "Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration", APPLIED PHYSICS B-LASERS AND OPTICS., NOV, {2014}. Vol. {117}({2}), pp. 645-657.
Abstract: We have developed a portable photoacoustic spectrometer that offers
routine, precise and accurate measurements of the molar concentration of
atmospheric carbon. The temperature-controlled spectrometer continuously
samples dried atmospheric air and employs an intensity-modulated
distributed feedback laser and fiber amplifier operating near 1.57 A mu
m. For measurements of carbon dioxide in air, we demonstrate a
measurement precision (60-s averaging time) of 0.15 A mu mol mol(-1) and
achieve a standard uncertainty of 0.8 A mu mol mol(-1) by calibrating
the analyzer response in terms of certified gas mixtures. We also
investigate how water vapor affects the photoacoustic signal by
promoting collisional relaxation of the carbon dioxide.
BibTeX:
@article{reed14a,
  author = {Reed, Zachary D. and Sperling, Brent and van Zee, Roger D. and Whetstone, James R. and Gillis, Keith A. and Hodges, Joseph T.},
  title = {Photoacoustic spectrometer for accurate, continuous measurements of atmospheric carbon dioxide concentration},
  journal = {APPLIED PHYSICS B-LASERS AND OPTICS},
  year = {2014},
  volume = {117},
  number = {2},
  pages = {645--657},
  doi = {10.1007/s00340-014-5878-y}
}
Rella CW, Chen H, Andrews AE, Filges A, Gerbig C, Hatakka J, Karion A, Miles NL, Richardson SJ, Steinbacher M, Sweeney C, Wastine B and Zellweger C ({2013}), "High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {6}({3}), pp. 837-860.
Abstract: Traditional techniques for measuring the mole fractions of greenhouse
gases in the well-mixed atmosphere have required dry sample gas streams
(dew point < -25 degrees C) to achieve the inter-laboratory
compatibility goals set forth by the Global Atmosphere Watch programme
of the World Meteorological Organisation (WMO/GAW) for carbon dioxide
(+/- 0.1 ppm in the Northern Hemisphere and +/- 0.05 ppm in the Southern
Hemisphere) and methane (+/- 2 ppb). Drying the sample gas to low levels
of water vapour can be expensive, time-consuming, and/or problematic,
especially at remote sites where access is difficult. Recent advances in
optical measurement techniques, in particular cavity ring down
spectroscopy, have led to the development of greenhouse gas analysers
capable of simultaneous measurements of carbon dioxide, methane and
water vapour. Unlike many older technologies, which can suffer from
significant uncorrected interference from water vapour, these
instruments permit accurate and precise greenhouse gas measurements that
can meet the WMO/GAW inter-laboratory compatibility goals (WMO, 2011a)
without drying the sample gas. In this paper, we present laboratory
methodology for empirically deriving the water vapour correction
factors, and we summarise a series of in-situ validation experiments
comparing the measurements in humid gas streams to well-characterised
dry-gas measurements. By using the manufacturer-supplied correction
factors, the dry-mole fraction measurements have been demonstrated to be
well within the GAW compatibility goals up to a water vapour
concentration of at least 1%. By determining the correction factors for
individual instruments once at the start of life, this water vapour
concentration range can be extended to at least 2% over the life of the
instrument, and if the correction factors are determined periodically
over time, the evidence suggests that this range can be extended up to
and even above 4% water vapour concentrations.
BibTeX:
@article{rella13a,
  author = {Rella, C. W. and Chen, H. and Andrews, A. E. and Filges, A. and Gerbig, C. and Hatakka, J. and Karion, A. and Miles, N. L. and Richardson, S. J. and Steinbacher, M. and Sweeney, C. and Wastine, B. and Zellweger, C.},
  title = {High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2013},
  volume = {6},
  number = {3},
  pages = {837--860},
  doi = {10.5194/amt-6-837-2013}
}
Reuter M, Buchwitz M, Schneising O, Heymann J, Bovensmann H and Burrows JP ({2010}), "A method for improved SCIAMACHY CO2 retrieval in the presence of optically thin clouds", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {3}({1}), pp. 209-232.
Abstract: An optimal estimation based retrieval scheme for satellite based
retrievals of XCO2 ( the dry air column averaged mixing ratio of
atmospheric CO2) is presented enabling accurate retrievals also in the
presence of thin clouds. The proposed method is designed to analyze
near-infrared nadir measurements of the SCIAMACHY instrument in the CO2
absorption band at 1580 nm and in the O-2-A absorption band at around
760nm. The algorithm accounts for scattering in an optically thin cirrus
cloud layer and at aerosols of a default profile. The scattering
information is mainly obtained from the O-2-A band and a merged fit
windows approach enables the transfer of information between the O-2-A
and the CO2 band. Via the optimal estimation technique, the algorithm is
able to account for a priori information to further constrain the
inversion. Test scenarios of simulated SCIAMACHY sun-normalized radiance
measurements are analyzed in order to specify the quality of the
proposed method. In contrast to existing algorithms for SCIAMACHY
retrievals, the systematic errors due to cirrus clouds with optical
thicknesses up to 1.0 are reduced to values below 4ppm for most of the
analyzed scenarios. This shows that the proposed method has the
potential to reduce uncertainties of SCIAMACHY retrieved XCO2 making
this data product potentially useful for surface flux inverse modeling.
BibTeX:
@article{reuter10a,
  author = {Reuter, M. and Buchwitz, M. and Schneising, O. and Heymann, J. and Bovensmann, H. and Burrows, J. P.},
  title = {A method for improved SCIAMACHY CO2 retrieval in the presence of optically thin clouds},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2010},
  volume = {3},
  number = {1},
  pages = {209--232},
  doi = {10.5194/amt-3-209-2010}
}
Reuter M, Bovensmann H, Buchwitz M, Burrows JP, Connor BJ, Deutscher NM, Griffith DWT, Heymann J, Keppel-Aleks G, Messerschmidt J, Notholt J, Petri C, Robinson J, Schneising O, Sherlock V, Velazco V, Warneke T, Wennberg PO and Wunch D ({2011}), "Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: Validation with FTS measurements and comparison with model results", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES., FEB 23, {2011}. Vol. {116}
Abstract: The Bremen Optimal Estimation differential optical absorption
spectroscopy (DOAS) (BESD) algorithm for satellite based retrievals of
XCO2 (the column-average dry-air mole fraction of atmospheric CO2) has
been applied to Scanning Imaging Absorption Spectrometer for Atmospheric
Cartography (SCIAMACHY) data. It uses measurements in the O-2-A
absorption band to correct for scattering of undetected clouds and
aerosols. Comparisons with precise and accurate ground-based Fourier
transform spectrometer (FTS) measurements at four Total Carbon Column
Observing Network (TCCON) sites have been used to quantify the quality
of the new SCIAMACHY XCO2 data set. Additionally, the results have been
compared to NOAA's assimilation system CarbonTracker. The comparisons
show that the new retrieval meets the expectations from earlier
theoretical studies. We find no statistically significant regional XCO2
biases between SCIAMACHY and the FTS instruments. However, the standard
error of the systematic differences is in the range of 0.2 ppm and 0.8
ppm. The XCO2 single-measurement precision of 2.5 ppm is similar to
theoretical estimates driven by instrumental noise. There are no
significant differences found for the year-to-year increase as well as
for the average seasonal amplitude between SCIAMACHY XCO2 and the
collocated FTS measurements. Comparison of the year-to-year increase and
also of the seasonal amplitude of CarbonTracker exhibit significant
differences with the corresponding FTS values at Darwin. Here the
differences between SCIAMACHY and CarbonTracker are larger than the
standard error of the SCIAMACHY values. The difference of the seasonal
amplitude exceeds the significance level of 2 standard errors.
Therefore, our results suggest that SCIAMACHY may provide valuable
additional information about XCO2, at least in regions with a low
density of in situ measurements.
BibTeX:
@article{reuter11a,
  author = {Reuter, M. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Connor, B. J. and Deutscher, N. M. and Griffith, D. W. T. and Heymann, J. and Keppel-Aleks, G. and Messerschmidt, J. and Notholt, J. and Petri, C. and Robinson, J. and Schneising, O. and Sherlock, V. and Velazco, V. and Warneke, T. and Wennberg, P. O. and Wunch, D.},
  title = {Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: Validation with FTS measurements and comparison with model results},
  journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
  year = {2011},
  volume = {116},
  doi = {10.1029/2010JD015047}
}
Reuter M, Buchwitz M, Schneising O, Hase F, Heymann J, Guerlet S, Cogan AJ, Bovensmann H and Burrows JP ({2012}), "A simple empirical model estimating atmospheric CO2 background concentrations", ATMOSPHERIC MEASUREMENT TECHNIQUES. Vol. {5}({6}), pp. 1349-1357.
Abstract: A simple empirical CO2 model (SECM) is presented to estimate
column-average dry-air mole fractions of atmospheric CO2 (XCO2) as well
as mixing ratio profiles. SECM is based on a simple equation depending
on 17 empirical parameters, latitude, and date. The empirical parameters
have been determined by least squares fitting to NOAA's (National
Oceanic and Atmospheric Administration) assimilation system
CarbonTracker version 2010 (CT2010). Comparisons with TCCON (total
carbon column observing network) FTS (Fourier transform spectrometer)
measurements show that SECM XCO2 agrees quite well with reality. The
synthetic XCO2 values have a standard error of 1.39 ppm and systematic
station-to-station biases of 0.46 ppm. Typical column averaging kernels
of the TCCON FTS, a SCIAMACHY (Scanning Imaging Absorption Spectrometer
for Atmospheric CHartographY), and two GOSAT (Greenhouse gases Observing
SATellite) XCO2 retrieval algorithms have been used to assess the
smoothing error introduced by using SECM profiles instead of CT2010
profiles as a priori. The additional smoothing error amounts to 0.17 ppm
for a typical SCIAMACHY averaging kernel and is most times much smaller
for the other instruments (e.g. 0.05 ppm for a typical TCCON FTS
averaging kernel). Therefore, SECM is well suited to provide a priori
information for state-of-the-art ground-based (FTS) and satellite-based
(GOSAT, SCIAMACHY) XCO2 retrievals. Other potential applications are:
(i) near real-time processing systems (that cannot make use of models
like CT2010 operated in delayed mode), (ii) `CO2 proxy' methods for XCH4
retrievals (as correction for the XCO2 background), and (iii) observing
system simulation experiments especially for future satellite missions.
BibTeX:
@article{reuter12a,
  author = {Reuter, M. and Buchwitz, M. and Schneising, O. and Hase, F. and Heymann, J. and Guerlet, S. and Cogan, A. J. and Bovensmann, H. and Burrows, J. P.},
  title = {A simple empirical model estimating atmospheric CO2 background concentrations},
  journal = {ATMOSPHERIC MEASUREMENT TECHNIQUES},
  year = {2012},
  volume = {5},
  number = {6},
  pages = {1349--1357},
  doi = {10.5194/amt-5-1349-2012}
}
Reuter M, Bovensmann H, Buchwitz M, Burrows JP, Deutscher NM, Heymann J, Rozanov A, Schneising O, Suto H, Toon GC and Warneke T ({2012}), "On the potential of the 2041-2047 nm spectral region for remote sensing of atmospheric CO2 isotopologues", JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER., NOV, {2012}. Vol. {113}({16}), pp. 2009-2017.
Abstract: Pressing open questions about the carbon cycle can be addressed with
precise measurements of the three most abundant CO2 isotopologues
(OCO)-O-16-C-12-O-16, (OCO)-O-16-C-13-O-16, and (OCO)-O-16-C-12-O-18.
Such measurements can, e.g., help to further constrain oceanic and
biospheric net fluxes or to differentiate between the gross biospheric
fluxes photosynthesis and respiration. The 2041-2047 nm (about 4885-4900
cm(-1)) spectral region contains separated absorption lines of the three
most abundant CO2 isotopologues. Their spectral properties make this
spectral region well suited for the use of a light path proxy method for
the retrieval of delta C-13 and delta O-18 (the ratio of heavier to
lighter isotopologues relative to a standard). An optimal estimation
based light path proxy retrieval for delta C-13 and delta O-18 has been
set up, applicable to GOSAT (Greenhouse gases Observing Satellite) and
ground-based FTS (Fourier transform spectrometer) measurements. Initial
results show that it is possible to retrieve delta C-13 and delta O-18
from ground-based FTS instruments with a precision of 0.6-1.6 parts per
thousand and from GOSAT with a precision of about 30 parts per thousand.
Comparison of the achievable precision with the expected atmospheric
signals shows that ground-based FTS remote sensing measurements have the
potential to gain valuable information on delta C-13 and delta O-18 if
averaging a sufficient number of measurements. It seems unlikely that
this applies also to GOSAT because of the lower precision and a
conceptual larger sensitivity to scattering related errors in satellite
viewing geometry. (C) 2012 Elsevier Ltd. All rights reserved.
BibTeX:
@article{reuter12b,
  author = {Reuter, M. and Bovensmann, H. and Buchwitz, M. and Burrows, J. P. and Deutscher, N. M. and Heymann, J. and Rozanov, A. and Schneising, O. and Suto, H. and Toon, G. C. and Warneke, T.},
  title = {On the potential of the 2041-2047 nm spectral region for remote sensing of atmospheric CO2 isotopologues},
  journal = {JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER},
  year = {2012},
  volume = {113},
  number = {16},
  pages = {2009--2017},
  doi = {10.1016/j.jqsrt.2012.07.013}
}
Reuter M, Boesch H, Bovensmann H, Bril A, Buchwitz M, Butz A, Burrows JP, O'Dell CW, Guerlet S, Hasekamp O, Heymann J, Kikuchi N, Oshchepkov S, Parker R, Pfeifer S, Schneising O, Yokota T and Yoshida Y ({2013}), "A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {13}({4}), pp. 1771-1780.
Abstract: We analyze an ensemble of seven XCO2 retrieval algorithms for SCIAMACHY
(scanning imaging absorption spectrometer of atmospheric chartography)
and GOSAT (greenhouse gases observing satellite). The ensemble spread
can be interpreted as regional uncertainty and can help to identify
locations for new TCCON (total carbon column observing network)
validation sites. Additionally, we introduce the ensemble median
algorithm EMMA combining individual soundings of the seven algorithms
into one new data set. The ensemble takes advantage of the algorithms'
independent developments. We find ensemble spreads being often < 1 ppm
but rising up to 2 ppm especially in the tropics and East Asia. On the
basis of gridded monthly averages, we compare EMMA and all individual
algorithms with TCCON and CarbonTracker model results (potential
outliers, north/south gradient, seasonal (peak-to-peak) amplitude,
standard deviation of the difference). Our findings show that EMMA is a
promising candidate for inverse modeling studies. Compared to
CarbonTracker, the satellite retrievals find consistently larger
north/south gradients (by 0.3-0.9 ppm) and seasonal amplitudes (by
1.5-2.0 ppm).
BibTeX:
@article{reuter13a,
  author = {Reuter, M. and Boesch, H. and Bovensmann, H. and Bril, A. and Buchwitz, M. and Butz, A. and Burrows, J. P. and O'Dell, C. W. and Guerlet, S. and Hasekamp, O. and Heymann, J. and Kikuchi, N. and Oshchepkov, S. and Parker, R. and Pfeifer, S. and Schneising, O. and Yokota, T. and Yoshida, Y.},
  title = {A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2013},
  volume = {13},
  number = {4},
  pages = {1771--1780},
  doi = {10.5194/acp-13-1771-2013}
}
Reuter M, Buchwitz M, Hilboll A, Richter A, Schneising O, Hilker M, Heymann J, Bovensmann H and Burrows JP ({2014}), "Decreasing emissions of NOx relative to CO2 in East Asia inferred from satellite observations", NATURE GEOSCIENCE., NOV, {2014}. Vol. {7}({11}), pp. 792-795.
Abstract: At present, global CO2 emission inventories are mainly based on
bottom-up estimates that rely, for example, on reported fossil fuel
consumptions and fuel types(1,2). The associated uncertainties propagate
into the CO2-to-NOx emission ratios that are used in pollution
prediction and monitoring(3), as well as into biospheric carbon fluxes
derived by inverse models(4). Here we analyse simultaneous and
co-located satellite retrievals from SCIAMACHY (ref. 5; SCanning Imaging
Absorption SpectroMeter for Atmospheric CHartographY) of the
column-average dry-air mole fraction of CO2 (refs 6,7) and NO2 (refs
8-10) for the years 2003-2011 to provide a top-down estimate of trends
in emissions and in the ratio between CO2 and NOx emissions. Our
analysis shows that the CO2-to-NOx emission ratio has increased by 4.2
+/- 1.7% yr(-1) in East Asia. In this region, we find a large positive
trend of CO2 emissions (9.8 +/- 1.7% yr(-1)), which we largely
attribute to the growing Chinese economy. This trend exceeds the
positive trend of NOx emissions (5.8 +/- 0.9% yr(-1)). Our findings
suggest that the recently installed and renewed technology in East Asia,
such as power plants, transportation and so on, is cleaner in terms of
NOx emissions than the old infrastructure, and roughly matches relative
emission levels in North America and Europe.
BibTeX:
@article{reuter14a,
  author = {Reuter, M. and Buchwitz, M. and Hilboll, A. and Richter, A. and Schneising, O. and Hilker, M. and Heymann, J. and Bovensmann, H. and Burrows, J. P.},
  title = {Decreasing emissions of NOx relative to CO2 in East Asia inferred from satellite observations},
  journal = {NATURE GEOSCIENCE},
  year = {2014},
  volume = {7},
  number = {11},
  pages = {792--795},
  doi = {10.1038/NGEO2257}
}
Reuter M, Buchwitz M, Hilker M, Heymann J, Schneising O, Pillai D, Bovensmann H, Burrows JP, Boesch H, Parker R, Butz A, Hasekamp O, O'Dell CW, Yoshida Y, Gerbig C, Nehrkorn T, Deutscher NM, Warneke T, Notholt J, Hase F, Kivi R, Sussmann R, Machida T, Matsueda H and Sawa Y ({2014}), "Satellite-inferred European carbon sink larger than expected", ATMOSPHERIC CHEMISTRY AND PHYSICS. Vol. {14}({24}), pp. 13739-13753.
Abstract: Current knowledge about the European terrestrial biospheric carbon sink,
from the Atlantic to the Urals, relies upon bottom-up inventory and
surface flux inverse model estimates (e.g. 0.27 +/- 0.16 GtCa(-1) for
2000-2005 (Schulze et al., 2009), 0.17 +/- 0.44 GtCa(-1) for 2001-2007
(Peters et al., 2010), 0.45 +/- 0.40 GtCa(-1) for 2010 (Chevallier et
al., 2014), 0.40 +/- 0.42 GtCa(-1) for 2001-2004 (Peylin et al., 2013)).
Inverse models assimilate in situ CO2 atmospheric concentrations
measured by surface-based air sampling networks. The intrinsic
sparseness of these networks is one reason for the relatively large flux
uncertainties (Peters et al., 2010; Bruhwiler et al., 2011).
Satellite-based CO2 measurements have the potential to reduce these
uncertainties (Miller et al., 2007; Chevallier et al., 2007). Global
inversion experiments using independent models and independent GOSAT
satellite data products consistently derived a considerably larger
European sink (1.0-1.3 GtCa(-1) for 09/2009-08/2010 (Basu et al., 2013),
1.2-1.8 GtCa(-1) in 2010 (Chevallier et al., 2014)). However, these
results have been considered unrealistic due to potential retrieval
biases and/or transport errors (Chevallier et al., 2014) or have not
been discussed at all (Basu et al., 2013; Takagi et al., 2014). Our
analysis comprises a regional inversion approach using STILT (Gerbig et
al., 2003; Lin et al., 2003) short-range (days) particle dispersion
modelling, rendering it insensitive to large-scale retrieval biases and
less sensitive to long-range transport errors. We show that the
satellite-derived European terrestrial carbon sink is indeed much larger
(1.02 +/- 0.30 GtCa(-1) in 2010) than previously expected. This is
qualitatively consistent among an ensemble of five different inversion
set-ups and five independent satellite retrievals (BESD (Reuter et al.,
2011) 2003-2010, ACOS (O'Dell et al., 2012) 2010, UoL-FP (Cogan et al.,
2012) 2010, RemoTeC (Butz et al., 2011) 2010, and NIES (Yoshida et al.,
2013) 2010) using data from two different instruments (SCIAMACHY
(Bovensmann et al., 1999) and GOSAT (Kuze et al., 2009)). The difference
to in situ based inversions (Peylin et al., 2013), whilst large with
respect to the mean reported European carbon sink (0.4 GtCa(-1) for
2001-2004), is similar in magnitude to the reported uncertainty (0.42
GtCa(-1)). The highest gain in information is obtained during the
growing season when satellite observation conditions are advantageous, a
priori uncertainties are largest, and the surface sink maximises; during
the dormant season, the results are dominated by the a priori. Our
results provide evidence that the current understanding of the European
carbon sink has to be revisited.
BibTeX:
@article{reuter14b,
  author = {Reuter, M. and Buchwitz, M. and Hilker, M. and Heymann, J. and Schneising, O. and Pillai, D. and Bovensmann, H. and Burrows, J. P. and Boesch, H. and Parker, R. and Butz, A. and Hasekamp, O. and O'Dell, C. W. and Yoshida, Y. and Gerbig, C. and Nehrkorn, T. and Deutscher, N. M. and Warneke, T. and Notholt, J. and Hase, F. and Kivi, R. and Sussmann, R. and Machida, T. and Matsueda, H. and Sawa, Y.},
  title = {Satellite-inferred European carbon sink larger than expected},
  journal = {ATMOSPHERIC CHEMISTRY AND PHYSICS},
  year = {2014},
  volume = {14},
  number = {24},
  pages = {13739--13753},
  doi = {10.5194/acp-14-13739-2014}
}
Reuter M, Buchwitz M, Schneising O, Noel S, Rozanov V, Bovensmann H and Burrows JP ({2017}), "A Fast Atmospheric Trace Gas Retrieval for Hyperspectral Instruments Approximating Multiple ScatteringPart 1: Radiative Transfer and a Potential OCO-2 XCO2 Retrieval Setup", REMOTE SENSING., NOV, {2017}. Vol. {9}({11})
Abstract: Satellite retrievals of the atmospheric dry-air column-average mole
fraction of CO2 (XCO2) based on hyperspectral measurements in
appropriate near (NIR) and short wave infrared (SWIR) O2 and CO2
absorption bands can help to answer important questions about the carbon
cycle but the precision and accuracy requirements for XCO2 data products
are demanding. Multiple scattering of light at aerosols and clouds can
be a significant error source for XCO2 retrievals. Therefore, so called
full physics retrieval algorithms were developed aiming to minimize
scattering related errors by explicitly fitting scattering related
properties such as cloud water/ ice content, aerosol optical thickness,
cloud height, etc. However, the computational costs for multiple
scattering radiative transfer (RT) calculations can be immense.
Processing all data of the Orbiting Carbon Observatory-2 (OCO-2) can
require up to thousands of CPU cores and the next generation of CO2
monitoring satellites will produce at least an order of magnitude more
data. Here we introduce the Fast atmOspheric traCe gAs retrievaL FOCAL
including a scalar RT model which approximates multiple scattering
effects with an analytic solution of the RT problem of an isotropic
scattering layer and a Lambertian surface. The computational performance
is similar to an absorption only model and currently determined by the
convolution of the simulated spectra with the instrumental line shape
function (ILS). We assess FOCAL's quality by confronting it with
accurate multiple scattering vector RT