Measurements of CO₂ concentration are carried out on a weekly basis since 1992 on the island of Lampedusa (35.5°N, 12.6°E), in the Mediterranean. Measurements are based at the Station for Climate Observations, which rests on a rocky plateau (45 m asl) on the North-Eastern coast of the island, and are made with a NDIR analyzer. World Meteorological Organization (WMO) reference standards are used for calibrations.  Continuous measurements were started in 1998; they were interrupted in early 2003, and activated again in 2005. The continuous observations show evidence of a small daily cycle (amplitude < ±1 ppm) only during the months of June, July, and August. Mean annual cycles derived from weekly flask measurements show a dependency on the wind origin: the annual cycle and the annual CO₂ mean are smaller for winds originating from the Southern sectors, than for winds from Northern sectors. The continuous measurements were combined with daily backward airmass trajectories to identify the dependency of the CO₂ amount on the airmass origin. Trajectories provided by National Oceanic and Atmospheric Administration / Air Resources Laboratory (Hysplit) are used. During winter, low CO₂ is generally connected to Southern/South-Eastern airmasses. In summer airmasses from North often display lower CO₂ content, due to the influence of the European sink.

The Total Carbon Column Observing Network is a new network of ground-based solar observatories, dedicated to column measurements of greenhouse gases.  We present CO₂ column abundances observed in Park Falls, Wisconsin and Lauder, New Zealand during May 2004 – June 2005.  In Park Falls, Wisconsin, the peak-to-peak variation of column-average CO₂ is approximately 13 ppmv.  In Lauder, New Zealand, the peak-to-peak variation of column-average CO₂ is approximately 4 ppmv.  Assuming a secular trend of 2 ppmv yr^-1, we infer a peak-to-peak seasonal amplitude of 11 ppmv and 2 ppmv for Park Falls and Lauder respectively.  These values are higher than model predictions by Olsen and Randerson [2003].

Based on simulations with high-resolution transport models we investigate the detectability of surface flux signals in the atmospheric CO₂ concentration and infer some general guidelines for the sampling of the continental troposphere for the purpose of constraining mid-latitude land carbon sinks.

A combined study of micrometeorological flux measurement of carbon dioxide (CO₂) and methane (CH₄) and measurement of their stable carbon isotopes at a paddy field indicated that CH₄ production can affect not only greenhouse gas budget of wetland ecosystem but also isotopic signature of respired CO₂.

The results of an optimisation of inter-annual methane sources and sinks calculated by inversion of atmospheric observations are presented and analysed for the 1984-2003 period. We focus our presentation on sources trend and inter-annual variability. Comparisons with bottom-up estimates are presented for biomass burning and wetlands emissions (only in the poster).

The influence of air-sea fluxes on atmospheric oxygen can be separated from terrestrial influences using the tracer Atmospheric Potential Oxygen (APO).  Data collected by the Scripps atmospheric oxygen flask sampling network exhibits interannual variability in APO coherent over the northern hemisphere.  The timing of these changes correlates with climatic changes in the North Pacific.

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.

We investigated the interannual variability of the partial pressure of carbon dioxide (pCO₂) in the surface waters of the western subarctic gyre (155°E to 165°E, 48°N to 53°N) and the Alaska Gyre (AG, 195°E to 210°E, 45°N to 52°N) for a period of 9 years. We used automated measurements of pCO₂ in the surface water (pCO_2sw) and the air (pCO_2air) as well as sea surface temperature (SST) and salinity (S) obtained from the Japanese-Canadian joint Volunteer Observing Ship (VOS) program. We observed annual trends in the pCO_2sw and based on simple least square fit to observed data, the surface waters in the WSG showed a gradual pCO_2sw increase of 0.4 ppm yr^-1 which was three times larger than in the AG (1.8 ppm yr^-1) for the 9-year period. In the WSG, this was about half of the estimated atmospheric pCO₂ increase for the whole period (10 ppm or 1.2 ppm yr^-1), whereas gas exchange explained much of the increase in the AG (pCO_2air increased 1.6 ppm yr^-1). Interestingly, the two gyres showed opposite annual trends in the SST and salinity and in the WSG we observed a salinity and SST increase of 0.018 yr^-1 and 0.07°C yr^-1 (0.56°C for the whole study period), respectively, whereas we observed a small freshening of 0.015 yr^-1 and a cooling trend of about 0.11°C yr^-1 in the AG. We examine the possible mechanisms to explain the annual trends in pCO₂, based on the observed changes in SST and salinity as well as observations made by other investigators.

Since 1993, regular seasonal water sampling has been conducted along a ship-track between Island and Newfoundland in the open ocean of the North Atlantic subpolar gyre in the frame of the long-term SURATLANT program. In this study, we analyse the interannual variation of the carbon dioxide system, including seawater fugacity (fCO₂) and air-sea CO₂ fluxes for the period 1993-2004. During 1993-1997, the data present a clear seasonality in this region marked by a strong CO₂ sink in summer and near-equilibrium in winter. For recent years, 2001-2004, we observed a dramatic change of the source/sink seasonality. An extreme case was observed in 2003 when oceanic fCO₂ was above equilibrium during all seasons. This strong anomaly was driven by ocean warming.

The spatial and temporal variations of atmospheric CO₂ at 8-13 km from April 1993 to March 2005 were observed by measuring CO₂ concentrations in samples collected biweekly from a commercial airliner between Australia and Japan. The 12-year record between 30N and 30S revealed several characteristics for CO₂ interannual variabilities in the upper troposphere. The most significant year-to-year change was found in a large increase in the growth rate during 1997/98 and 2002/03 that were associated with the ENSO events. During these years, changes in north-to-south gradient of latitudinal distribution and seasonal cycle were observed compared to data during the normal years.