WHAT CAN WE LEARN FROM INTENSIVE ATMOSPHERIC SAMPLING FIELD PROGRAMS?
Description:
Intensive atmospheric
sampling field programs are envisioned as a key component of integrated
research programs such as the North American Carbon Program (NACP) [Sarmiento and Wofsy,
1999; Wofsy and Harriss, 2002]. The intensive
sampling provides unique information about the spatial distribution of CO2
as well as imposes tight constraints on regional budgets that are difficult to
obtain from other means. We summarize what we have learned from the numerous
COBRA (CO2 Budget and Rectification Airborne study) experiments [Gerbig et al.,
2003a] that have taken place in 2000, 2003, and 2004. We present the observed spatial variability
of CO2 [Gerbig et al., 2003a; Lin et al.,
2004a] and regional budgets derived from regional air
parcel-following experiments [Lin et al., 2004b]. These
observations are also used as a critical testbed for modeling frameworks [Gerbig et al.,
2003b]. We draw conclusions about ways to maximize the value
of intensive atmospheric sampling experiments and the role that such
experiments should play within programs like the NACP.
Author's Names: J.C. Lin, C. Gerbig, S.C. Wofsy, B.C. Daube, et al
Filesize: 721.39 Kb
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WHAT CAN TRACER OBSERVATIONS IN THE CONTINENTAL BOUNDARY LAYER TELL US ABOUT SURFACE-ATMOSPHERE ...
Description:
There
are two basic approaches for inferring surface-atmosphere exchange for trace
gases on regional scales: a bottom-up approach, in which local process
knowledge is scaled up, and a top-down approach, in which the larger-scale
constraint from atmospheric concentration measurements is applied in
combination with transport models. Here we combine the two approaches, and
assess the information content added by boundary layer concentration data. More
specifically, we analyze the potential for inferring spatially resolved surface
fluxes from atmospheric tracer observations within the mixed layer, such as
from monitoring towers, using a receptor oriented transport model (Stochastic
Time-Inverted Lagrangian Transport [STILT] model, [Lin et al., 2003]) coupled to a
simple biosphere in which CO2 fluxes are represented as functional responses to
environmental drivers (radiation and temperature, [Gerbig et al., 2003]). Transport and
fluxes are coupled on a dynamic grid using a polar projection with high
horizontal resolution (~20 km) in near field, and low resolution far away (as
coarse as 2000 km), reducing the number of surface pixels without significant
loss of information. To test the system, and to evaluate the errors associated
with the retrieval of fluxes from atmospheric observations, a pseudo data
experiment was performed. A large number of realizations of measurements
(pseudo data) and a priori fluxes was generated, and for each case spatially
resolved fluxes were retrieved. Results indicate strong potential for high
resolution retrievals based on a network of tall towers, subject to the
requirement of correctly specifying the a priori uncertainty covariance,
especially the off diagonal elements that control spatial correlations.
Author's Names: C. Gerbig, J.C. Lin, J.W. Munger, and S.C. Wofsy
Filesize: 67.70 Kb
Added on: 28-Jul-2005 Downloads: 38
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VERTICAL PROFILES OF THE O2 N2 RATIO IN THE STRATOSPHERE OVER JAPAN AND ANTARCTICA
Description: To
examine vertical distributions of the O2/N2 ratio in the stratosphere, air
samples were collected using a cryogenic sampler over Sanriku,
Japan and Syowa, Antarctica. It
was clearly seen that d(O2/N2), as well as
simultaneously measured d15N of N2 and d18O of O2, decreased
gradually with increasing height in the stratosphere. The observed profiles of
stratospheric ï€ d15N and d18O were in good agreement
with those calculated using a steady state
1-dimensional eddy-diffusion/molecular-diffusion model suggesting that the
upward decrease of stratospheric d(O2/N2)
is caused by O2 and N2 molecules fractionated differently
by gravity. The stratospheric d(O2/N2) corrected for the
gravitational separation indicated that the average value at heights above
20-25 km over Sanriku was always higher than
the upper tropospheric d(O2/N2)
value over Japan
at the corresponding time, and that it has decreased secularly, as was found in
the troposphere.
Author's Names: Shigeyuki Ishidoya, Satoshi Sugawara, Gen Hashida, et al
Filesize: 111.87 Kb
Added on: 29-Jul-2005 Downloads: 28
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VERTICAL AIRCRAFT PROFILES OVER EUROPE
Description:
Regular vertical profiles over Europe were set up in
2001 as part of the AEROCARB and Carboeurope-IP projects at five locations:
Griffin (56°36'N, 3°47'W, Scotland), Orléans (47°50'N, 2°30'E, France),
Schauinsland (47°55'N, 7°55'E, Germany), Hegyhatsal (46°57'N, 16°39'E, Hungary),
and Bialystok (53.20°N, 22.75°E, Poland). The objective of the program is to
measure CO2, CH4, N2O, SF6, CO, 13C
and 18O in CO2 vertical profiles at a bi-weekly frequency
using air samples taken up at several levels from 100m up to 3000 m above the
ground surface. One liter flasks are sampled on board small aircraft using a
standardised protocol. The samples are analysed at three laboratories (LSCE,
MPI-BGC, IUP-UHEI) which are
linked through regular intercomparison exercises. We have characterised for
each site the CO2 seasonal cycles within the atmospheric boundary
layer (ABL: 14 to 20 ppm) and the
free troposphere (FT: 10 to 13 ppm). From these signals we have calculated the
difference between ABL and FT,
known as the CO2 'jump', which will be compared to the simulations
from atmospheric transport models. We have also calculated the offset between
each airborne sampling site and the time series from Mace Head observatory,
used as a maritime reference. For CO2, the wintertime offsets at the
lowest level of the average vertical profiles are ranging from 0 ppm in Scotland
up to 10 ppm in all continental sites. Depending of the site the positive
offset due to emissions from anthropogenic and biospheric processes may extend
up to 300 to 1500 m agl. In summertime we observe a negative gradient in most
of the sites with a typical decrease of 5 ppm between 2000m and 100m agl. The
average vertical gradients will be compared to the ouput of atmospheric models,
and will be analysed with regards to the other trace gas (CO, CH4,
and CO2 isotopes).
Author's Names: M. Ramonet, L.Haszpra, K. Katrynski, I. Levin, et al
Filesize: 16.60 Kb
Added on: 03-Aug-2005 Downloads: 33
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VARIATIONS OF OCEANIC PCO2 AND AIR-SEA CO2 FLUX IN THE GREENLAND SEA AND THE BARENTS SEA
Description:
In order to elucidate seasonal
and interannual variations of oceanic CO2 uptake in the Greenland
Sea and the Barents Sea, partial pressures of
CO2 in the surface ocean (pCO2sea)
were measured from 1992 to 2001. The values of pCO2sea
were lower than the partial CO2 pressures in the atmosphere (pCO2air) throughout the year, and the
annual net air-sea CO2 fluxes in the Greenland Sea and the Barents Sea were evaluated to be 52 ± 31 and 46 ± 27 gC m-2
yr-1, respectively, yielding a total oceanic CO2 uptake of
0.050 ± 0.030 GtC yr-1. We also found that the annual mean CO2
uptake was positively correlated with the North Atlantic Oscillation Index
(NAOI) via wind strength, but was negatively correlated with DpCO2 (pCO2air-pCO2sea) and the sea ice coverage. The
results also indicate that the wind speed and sea ice coverage play a major
role in determining the interannual variation of CO2 uptake, with DpCO2 playing a minor role.
Author's Names: S. Nakaoka, S. Aoki, T. Nakazawa, G. Hashida, et al
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Added on: 03-Aug-2005 Downloads: 19
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VARIATIONS IN ATMOSPHERIC O2 AND CO2 IN THE SOUTHERN OCEAN REGION FROM CONTINUOUS SHIP-BASED ...
Description:
Variations in atmospheric oxygen (O2) are a
sensitive indicator of biogeochemical processes involved in the global carbon
cycle. To improve our understanding of
these processes, we developed a system for continuous high precision
measurements of atmospheric O2 and CO2 that is suitable
for shipboard use. This system was
employed on two voyages in the Western Pacific sector of the Southern Ocean, in
February 2003 and April 2004. Elevated O2
concentrations were observed south of New Zealand and across the Chatham
Rise suggesting that these regions of ocean are outgassing O2 in
late summer to autumn.
Author's Names: R. L. Thompson, A. C. Manning, D. C. Lowe, and C. Rödenbeck
Filesize: 77.34 Kb
Added on: 08-Aug-2005 Downloads: 23
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VARIATIONS AND DISTRIBUTIONS OF pCO2 IN SURAFCE SEAWATER IN THE WESTERN NORTH PACIFIC ...
Description:
Measurements of the
partial pressure of CO2 in surface seawater (pCO2w)
have been made frequently and extensively in the western North Pacific (3-35°N,
132-142°E) since 1990. Based on the time series analysis of pCO2w
data, we obtained a “climatological view” of seasonal variation in pCO2w
in the western North Pacific. We have examined the relationship between pCO2w
and sea surface temperature (SST). The pCO2w–SST
relationship varies spatially and temporally. The pCO2w
showed an average growth rate of 1.6 µatm yr-1 (nearly equal to that
of the air, pCO2a) with large variability (±8.9µatm yr-1).
In 1998, larger growth rates of pCO2w occurred in the
subtropical gyre and the western equatorial Pacific, which was probably
associated with the 1997/98 El Niño phenomena. To know processes affecting
long-term variations in pCO2w, we have examined seasonal
variation in growth rate of pCO2w. The linear growth rate
of pCO2w during the winter season ranged from 1.3±0.2 to 2.1±0.2µatm yr-1 with an average of 1.7±0.2µatm
yr-1. During
spring/summer seasons, the
average growth rate of pCO2w was larger than 2µatm yr-1 north of 27°N, and within the range from
0 to 1µatm yr-1 in the North Equatorial Current. These increases were
mostly caused by the oceanic uptake of anthropogenic CO2, and to
some extent, other processes controlling the pCO2w change: thermodynamic effect, lateral
transport and vertical mixing, and biological activity.
Author's Names: H.Y. Inoue, M. Ishii, T. Midorikawa, A. Nakadate, et al
Filesize: 73.43 Kb
Added on: 29-Jul-2005 Downloads: 45
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VARIATIONAL DATA ASSIMILATION OF HIGH DENSITY ATMOSPHERIC CO2 DATA:...
Description: High-frequency atmospheric CO2 measurements
should become increasingly available by the end of this decade from a variety
of sources, including low-Earth orbiting satellites. If of sufficient accuracy,
these should allow the functioning of the global carbon cycle to be monitored
at fine time/space resolutions using atmospheric transport inversions. Since
traditional direct inversion methods (e.g., Bayesian synthesis) become
computationally infeasible at these resolutions, we use an approximate method,
variational data assimilation, to estimate surface CO2 fluxes at
spatial resolutions ranging from 10x10 degrees to 1x1 degrees and at time
resolutions ranging from 2 weeks to 1 hour. We assess its performance using simulated
data, including the effects of realistic transport and data errors.
Author's Names: D.F. Baker, S. Doney, and D. Schimel
Filesize: 12.88 Kb
Added on: 25-Jul-2005 Downloads: 33
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VARIABILITY OF OCEAN CO2 PARTIAL PRESSURE AND AIR-SEA CO2 FLUXES IN THE SUBANTARCTIC ZONE ...
Description: Seven CARIOCA lagrangian buoys drifted in the Subantarctic Zone, SAZ, of
the Indian and Pacific Ocean between 2001 and
2005. Measurements indicate that pCO2 in sea water is undersaturated
with respect to the atmospheric value and consequently the subantartic zone of
the Southern Ocean acts as a sink for atmospheric CO2 during all
seasons. Large observed pCO2 variability is associated with mixing
close to the subantarctic front, with biological activity and local warming.
These variabilities are higher than the seasonal cycle in the studied areas.
Author's Names: J. Boutin, L.Merlivat, and K.Currie
Filesize: 92.01 Kb
Added on: 27-Jul-2005 Downloads: 136
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USING INVERSE MODELLING TO INVESTIGATE POTENTIAL IR MEASUREMENT STRATEGIES FOR CONSTRAINING ...
Description:
CO2
and methane are important greenhouse gases, both contributing in increasing
amounts towards positive radiative forcing. It is hence important to gain
maximum understanding of the carbon cycle in the atmosphere, and the scale of
carbon trace gas sources and sinks, not only globally but also on a more
regional level. The Orbiting Carbon Observatory (OCO) satellite, scheduled for
launch in 2008, is designed for dedicated global mapping of CO2. In
order to investigate the usefulness of a variety of methods, including
retrievals from satellite mapping, some preliminary inverse modelling using a
Bayesian synthesis technique is performed using pseudodata generated to
represent possible future measurement regimes. This study will focus on the
ability of in-situ measurements within Australia to reduce the
uncertainties in Australian continental CO2 flux estimates. The
specific measurements investigated include a Ghan railway transect between
Adelaide (34.9°S, 138.6°E) and
Darwin (12.5°S, 130.9°E), and a number of continuous permanent sites. The
reduction in flux uncertainties from additional measurements compared to a
background inversion is examined, from which it is concluded that measuring on
the Ghan railway is potentially worthwhile for reducing uncertainties
associated with flux estimates.
Author's Names: N.M. Deutscher, R.M. Law, D.W.T. Griffith, and G.W. Bryant
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