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.

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 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.

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.

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.

We have employed a Multi-parameter Linear Regression (MLR) analysis procedure to determine the uptake of anthropogenic CO₂ between two east-west hydrographic surveys of the North Pacific that occurred in 1994 and 2004. The results revealed water column integrated uptake rates of anthropogenic CO₂ that ranged from 1.1 to 1.3 mol m^-2 yr^-1 depending on location. The combined effect of the tilted density surfaces and the younger waters with higher anthropogenic CO₂ concentrations leads to higher total column inventories in the western North Pacific.

In the present study atmospheric CO₂ retrievals based on Aqua satellite AIRS (Atmospheric Infrared Sounder) instrument observations are compared with forward model predictions. There is quite good agreement in seasonal cycles as well as North-South gradients when averaged over large scales. At smaller scales there are contrasts between upper troposphere CO₂ above continents versus oceans in the retrievals and there are signatures off Africa which seem likely artifacts caused by aerosols. As a consequence retrievals cannot be used at this stage to constrain surface sources and sinks without causing large biases. Interestingly there is good agreement in the shape of the N-S gradient at low-to-mid latitudes in the Northern hemisphere between simulations based on one transport model (LMDZ) and retrievals, but disagreement when comparing with simulations based on a second transport model (TM3). This raises questions about lower to upper troposphere transport and their representation in these models.

The carbon dioxide transport at the Niwot Ridge AmeriFlux site was investigated in both gravity and streamline coordinates. For this forested site with a 6% slope, both nighttime drainage flow and daytime upslope flow played important roles in the CO₂ budget. Both the CO₂ respiration at night and the CO₂ uptake during the day are underestimated if the horizontal transport of CO₂ is not monitored; and the two components may not cancel out.

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.