The synoptic scale atmosphere-biosphere interaction can cause anomalies of ~10 ppm with length scale of ~1000 km in the monthly averaged surface CO₂ concentration. These anomalies may contribute to the errors and uncertainties of CO₂ inversion estimates.

Over the last decade the TransCom group has coordinated a number of intercomparisons. The latest project focuses on the diurnal and synoptic behaviour of transport models.  The poster will describe the experiment, introduce the participating models and present a sample of preliminary results.

The role of the Southern Ocean as a source or a sink for CO₂ in the modern ocean is heavily disputed, its interannual variability is unknown, and its control on atmospheric CO₂ during glaciations is suspected but still not understood nor quantified.  We estimate the variability of the air-sea CO₂ fluxes in the Southern Ocean for the 1992-2003 period using the spatio-temporal distribution of atmospheric CO₂ measurements from 12 stations in the Southern Ocean and 43 stations worldwide.  Our results show basin-scale variability of ±0.1 to 0.3 PgC/y that are related to physical variability in the Southern Ocean.

The coupled feedback processes of energy and carbon cycles are an essential mechanism for understanding global environmental change. We developed a simplified one-dimensional carbon and energy cycle coupled model to quantify the feedback processes between energy and carbon cycles. The model was calibrated to reproduce the historical variations in temperature and atmospheric CO₂ concentration. The model results of vertical ocean temperature profiles, and latitudinal NPP and NEP distributions were in good agreement with the observation data and terrestrial biosphere model results. The regional difference of terrestrial ecosystem response by climate feedback appeared in the middle and high latitudes. The north-south distribution is important to investigate the terrestrial ecosystem because the opposite response appeared in the middle and high latitude. The future change of carbon cycle and climate was also simulated up to the year 2100 based on the IPCC scenario. The atmospheric CO₂ concentration reaches 735 ppmv in 2100 and global average temperature increases 1.9 K for 2000-2100.

Regular multi-year measurements of atmospheric CO₂ mixing ratios at a network of sites (Fig. 1) give quantitative spatial and temporal information on surface sources and sinks [e.g., Conway et al., 1994]. Using a global atmospheric tracer transport model in a high-resolution (daily, 4x5 degree pixels) inversion setup, we estimate surface-atmosphere CO₂ fluxes that give the best match between modelled and observed CO₂ concentrations. Building on an earlier study [Rödenbeck et al., 2003], this contribution (1) presents new CO₂ flux estimates using methodological developments, and (2) provides an update on interannual fluxes over the most recent anomalous time period 2002-2003.

We analysed the temporal variations of the CO₂ system in the Southern Ocean south of Tasmania and compared the seasonality of the carbon dioxide fugacity (fCO₂) and the air-sea CO₂ flux during spring and summer for two different years: 1996/97 and 2002/03. In summer, the CO₂ flux presents large and contrasting interannual changes in the Permanent Open Ocean Zone (POOZ, 53-61°S): the oceanic CO₂ sink varies from about –0.3 mmol.m^-2.d^-1 in 1997 to –20.6 mmol.m^-2.d^-1 in 2003. This strong sink in February 2003 was related to an increased phytoplankton biomass in this high-nutrient, low-chlorophyll (HNLC) region.

We will present our design of a new autonomous, inexpensive, and robust CO₂ analyzer (AIRCOA), a description of our quality control procedures, and data examples from ongoing deployments.  Our current AIRCOA units require less than $10K (USD) in components, show intercomparability better than 0.1 ppm during laboratory tests, and are designed to run autonomously for months at a time.

CHIOTTO – Continuous HIgh-precisiOn Tall Tower Observations of greenhouse gases – is a European Union-funded project which has as objective to build an infrastructure for the continuous monitoring of greenhouse gas concentrations across Europe above the surface layer using tall towers (~300m height). For this purpose a new analysis system for continuous atmospheric measurements was built and tested at Max Planck Institute for Biogeochemistry, Jena, Germany and was recently installed at a 300 m tower close to Bialystok, Poland (Lat 53°14'N, Long 23°01'E, Alt 180m), as part of the “CHIOTTO” tall tower network. Since July 2005 this system is measuring quasi-continuously the atmospheric concentration of CO₂, CH₄, CO, N₂O, SF₆ and the O₂/N₂ ratio as well as meteorological parameters (atmospheric pressure, temperature, humidity; wind speed and direction) from 5 heights on the tower ranging from 5 to 300 m. The measurement devices are: an Oxzilla O₂ fuel cell analyzer, a LiCor 7000 NDIR CO₂ analyzer, an Agilent gas chromatograph (GC) with flame ionization detector (FID) and electronic capture detector (ECD) for CH₄, CO, N₂O, SF₆. The challenge was to build a reliable automatic system which can run continuously with very little maintenance and to fulfill at the same time the high precision requirements for all the measured species prescribed by the CHIOTTO project goals. The high temporal resolution achieved will capture short term events and diurnal variability. In addition, the system is planned to run for at least several years in order to observe long-term trends as well. We describe the technical setup of the measurement system, the region of influence of the station and present the first months of data if available: correlations between species, observed short term variability patterns and their relation to meteorology and air parcel paths.