High-frequency atmospheric CO₂ measurements should become increasingly available by the end of this decade from a variety of sources, including low-Earth orbiting satellites. If of sufficient accuracy, these should allow the functioning of the global carbon cycle to be monitored at fine time/space resolutions using atmospheric transport inversions. Since traditional direct inversion methods (e.g., Bayesian synthesis) become computationally infeasible at these resolutions, we use an approximate method, variational data assimilation, to estimate surface CO₂ fluxes at spatial resolutions ranging from 10x10 degrees to 1x1 degrees and at time resolutions ranging from 2 weeks to 1 hour. We assess its performance using simulated data, including the effects of realistic transport and data errors.

Transport-based inversions of atmospheric CO₂ concentration measurements have been used by several groups [e.g., Bousquet, et al., 2000; Rödenbeck, et al., 2003; Baker, et al., 2005] to estimate monthly regional CO₂ fluxes from the 1980s to the present. When compared at the scale of broad latitude bands, the inter-annual variability (IAV) of these results is broadly consistent. This agreement breaks down, however, when the fluxes are partitioned regionally inside these latitude bands, or even into global land/ocean totals. We show here that this disagreement can largely be explained by random estimation errors and transport model errors affecting the estimates.

The CROZEX cruises (November 2004 to January 2005) had the objective to test whether natural iron fertilisation from the Crozet plateau promotes algal blooms. Results from the cruises show that algal blooms created an oceanic CO₂ sink downstream of the Crozet plateau. Vertical advection of water into the mixed layer occurred close to two islands on the plateau. Data from 18 cruises between 1991 and 2002 are used to quantify the seasonal variability of surface pCO₂ and CO₂ air-sea exchange in the region.

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 here a test of convection uncertainty within a single model framework driven by the same meteorological fields. Our primary goal is to explore to what extent do convection schemes impact atmospheric CO₂ distribution, by testing three referred cloud convection schemes ranging from a very simple to a relatively complex form [Table 1]. Our second goal is to examine the sensitivity of atmospheric CO₂ to its regional emission/sink uncertainty [Fig. 1] constrained by IPCC 2001 at a “fixed” convection scheme to clarify the pros and cons of the convection schemes.