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.

A detailed comparison of global atmospheric CH₄ retrievals from the space-borne spectrometer SCIAMACHY onboard the European environmental satellite ENVISAT is presented with the atmospheric transport models TM4 and TM5.

The CARBOOCEAN consortium aims at an accurate scientific assessment of the marine carbon sources and sinks within space and time. It will determine the ocean’s quantitative role for uptake of atmospheric carbon dioxide (CO₂), the most important manageable driving agent for climate change. Since the ocean has the most significant overall potential as a sink for anthropogenic CO2, the correct quantification of this sink is a fundamental necessary condition for all realistic prognostic climate simulations. Target is to reduce the present uncertainties in the quantification of net annual air-sea CO₂ fluxes by a factor of 2 for the world ocean and by a factor of 4 for the Atlantic Ocean.

The air-sea gas exchange rate is important for modeling and verifying ocean CO₂ uptake, but remains subject to considerable uncertainty. The widely assumed quadratic or cubic dependence of the exchange rate on windspeed together with the latitudinal pattern of mean windspeed implies that exchange is much faster at high compared with low latitudes. This should affect the pattern of ocean uptake of bomb carbon-14 as well as the rate of decline of and latitudinal gradients in atmospheric Δ¹⁴CO₂. We evaluate the constraints on the windspeed dependence of the exchange rate offered by available isotopic measurements, discuss the major uncertainties, and suggest observational strategies to reduce these uncertainties.

The formation of Antarctic Intermediate Water is investigated in a state of the art numerical model. Results are compared with a previous, lower resolution version of the model, and with data from the World Ocean Circulation Experiment.

We present preliminary results of a modeling experiment that compares observed vertical profiles of CO₂ with those generated by an atmospheric transport model (ATM). The ATM is driven by CO₂ flux fields generated from the inversion of monthly averaged CO₂ surface data (GLOBALVIEW). We note large differences between the best fit to the observations produced in the inversion and the same quantity simulated by the forward model. This difference arises from the nonlinearity of the advection scheme used in the transport model. When comparing with vertical profiles, we note that much of the difference between simulated and observed concentration has the same structure as the impact of this nonlinearity. Inversion schemes must therefore take nonlinearity into account. Despite these differences, the profiles are able to distinguish among inversions that fit subsets of the surface data, suggesting they are a useful validation dataset.

Mode Waters provides a privileged pathway for the transport of heat, salt and anthropogenic CO₂ into the ocean interior. The carbon cycle decadal variability in response to environmental changes is investigated using historical and recent data collected during the INDIGO (1985-1987) and OISO (1998-2003) oceanographic campaigns conducted in the South West Indian Ocean, an important zone for Mode Waters formation. The observed change in dissolved inorganic carbon over the 15-year period was 8 µmol/kg in Subantarctic Mode Water (500-800m), which is less than the anthropogenic carbon increase alone (13 µmol/kg). This difference may be explained by natural or climate-induced changes in ocean processes. Predictions from a global ocean-carbon model (OPA-PISCES) are used as a means to help interpret changes in the controlling processes: ocean dynamics, biological activity and air-sea interactions.

The current WMO CO₂ Mole Fraction Scale consists of a set of fifteen CO₂ –in-air primary standard calibration gases ranging in CO₂ mole fraction from 250 to 520 micromol/mol. Since the WMO CO₂ Expert Group transferred responsibility for maintaining the WMO Scale from the Scripps Institute of Oceanography (SIO) to the Climate Monitoring and Diagnostics Laboratory (CMDL) in 1995, the fifteen WMO primary standards have been calibrated at regular interval, between one and two years, by the CMDL manometric system. From mid-1996 to 2001, the assigned CO₂ values of the WMO Primaries have been jointly based on the SIO and CMDL manometric measurements, and completely on the CMDL manometric measurements alone from 2001 to present. The uncertainty of the 15 primary standards is estimated to be 0.07 micromol/mol in the one-sigma absolute scale. Manometric calibration results indicated that there is no evidence of overall drift of the Primaries from 1996 to 2004. In order to lengthen the useful life of the Primary standards, CMDL has always transferred the WMO Scale to the Secondaries via NDIR analyzers. The uncertainties arising from the analyzer random error and the propagation error due to the uncertainty of the reference gas concentration are discussed. Precision of NDIR transfer calibrations is about 0.01 micromol/mol from 1979 to present. Propagation of the uncertainty is calculated theoretically. In the case of interpolation, the propagation error is estimated to be between 0.05 and 0.07 micromol/mol when the Primaries are used as the reference gases via NDIR transfer calibrations.

Air-water CO₂ fluxes were up-scaled to take into account the latitudinal and ecosystem diversity of the coastal ocean, based on an exhaustive literature survey. Marginal seas at high and temperate latitudes act as sinks of CO₂ from the atmosphere, in contrast to subtropical and tropical marginal seas that act as sources of CO₂ to the atmosphere. Overall, marginal seas act as a strong sink of CO₂ of about -0.45 Pg C yr^-1. This sink could be almost fully compensated by the emission of CO₂ from the ensemble of near-shore coastal ecosystems of about 0.40 Pg C yr^-1.