We present a synthesis Bayesian inverse method to optimize one year of daily fluxes at model resolution (50x50 km over Europe) by inversion of continuous CO₂ measurements, daily averaged over Europe (10 sites). Based on a synthetic data analysis, we studied the impact of three different spatial and temporal correlations on flux errors. We found that the present network is too sparse to efficiently constrain European fluxes at model resolution even with the assumption of perfect transport. However, the agreement between the optimized fluxes and the true fluxes is improved when aggregated in space and time, mainly for 8-10 days fluxes over Western Europe. This region is indeed surrounded by our network. The spatial correlation scheme used was found to have a negligible impact on this agreement. Adding a white noise on pseudo-data to simulate transport model errors largely degrades the agreement. Using real data, European flux variations becomes unreasonably large due to the inability of our transport model to properly represent the CO₂ concentrations at continental sites.

This presentation will interpret results from the TransCom 3 interannual time dependent inversion. First, the long-term mean carbon exchange will be compared across the three different TransCom 3 inversion levels: the annual mean, seasonal, and interannual control experiments. We will highlight the agreement among these experiments in spite of the differing degrees of freedom, and the differing CO₂ observing networks employed. Comparison will be made to independent decadal estimates of land and ocean carbon uptake and will include the sensitivity to different CO₂ networks. We will also interpret the model mean interannual carbon fluxes as they relate to key indices of climate variability. In particular, correlation to the El Niño/Southern Oscillation index will be made suggesting a propagation carbon flux anomalies from the tropics to the extra tropics following the peak of the ENSO warm phase in the tropical Pacific ocean. These correlations will be explained via anomalies in temperature and precipitation from NCEP reanalysis.

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.

Exchange rates within the Global Carbon Cycle, between oceans, atmosphere and terrestrial biosphere – including the anthropogenic CO₂ production – are being traced by concentration and isotope ratio measurements of atmospheric CO₂. The background value of the stable isotope ratio of oxygen in atmospheric CO₂ is determined by oxygen exchange with the ocean surface waters. During contact with leaf water, the signature of this then evaporation-enriched groundwater (the extent still being dependent on plant physiological and environmental parameters), will be imprinted on CO₂ diffusing back out of the leaf stomata. From water cycle studies the continental effect (Rayleigh-distillation) is known, leading to precipitation strongly depleted in d¹⁸O over e.g. Siberia. This signal is also transferred into plant material. These main mechanisms within the ¹⁸O-cycle are known or under investigation. The d¹⁸O source term for atmospheric CO₂ derived from biomass burning and anthropogenic fossil fuel combustion, however, is less well-known.

Mt. Cimone Observatory is a background station for the measurement of greenhouse gases and other atmospheric pollutants located on the top of the highest peak of the Italian Northern Appenines. Continuous Measurements of atmospheric CO₂ were started in March 1979 by the Italian Air Force Meteorological Service using NDIR analysers. A number of case studies are presented in order to show the influence of certain polluted or vegetated areas on the concentration of carbon dioxide. Chemical tracers are used to asses the origin of the air masses together with an analysis of the back trajectories.

The Dole-Morita effect (DME) describes the d¹⁸O enrichment of atmospheric O₂ with respect to ocean water [Dole 1935, Morita 1935]. The magnitude of the DME (23.8 ± 0.1‰ at present, Horibe et al. [1973]) varies over geologic time scales, and might have changed as a result of human activity. Such variations are preserved in the air enclosed in polar firn and ice. Here, we explore the potential effects of human activity on the DME. We estimate that global changes in the land biosphere may have led to a decrease in the DME in the order of 0.07‰ over the last 150 years. We then predict profiles of d¹⁸O-O₂ in firn air resulting from a range of atmospheric scenarios using a model [Severinghaus and Battle, submitted] and compare the simulated profiles to measurements of air samples extracted from polar firn.

We present measurements of atmospheric O₂/N₂ ratio and CO₂ mole fractions from flask samples collected at Hateruma Island and Cape Ochi-Ishi, and onboard cargo ships between Japan and the United States, and Japan and Australia (or New Zealand). Average changes in the O₂ and CO₂ for the 6-year period from 1998 to 2004 are –23.3 ± 0.3 ppm and 10.4 ± 0.1 ppm, respectively. Assuming that the ocean is neither a source nor a sink for the atmospheric O₂, we estimate the CO₂ uptake by the terrestrial biosphere and the ocean to be 1.1 ± 0.6 PgC yr^-1 and 2.0 ± 0.5 PgC yr^-1, respectively.

Changes in dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) in the water column are quantified for meridional hydrographic sections through the Atlantic from 63 ˚N to 60 ˚S between 1988/1993 and 2003/2005.  Changes are most pronounced in the upper 1000 m water column.  DIC changes range from -5 to 40 µmol/kg and AOU changes by a similar amount.  The remainder is caused by changes in positions of fronts, gyres, remineralization and ventilation as manifested by changes in watermass properties.  In particular AOU increases of similar magnitude as increases in DIC point towards a significant contribution of oxidation of organic matter to the DIC increase.  The large changes in biogeochemical properties of the upper water column of the Atlantic have been one of the big surprises in the decadal reoccupation of the transects.