Influence of differences in current GOSAT XCO2 retrievals on surface flux estimation



We investigated differences in the five currently-available datasets of column-integrated CO2 concentrations (math formula) retrieved from spectral soundings collected by Greenhouse gases Observing SATellite (GOSAT) and assessed their impact on regional CO2 flux estimates. We did so by estimating the fluxes from each of the five math formula datasets combined with surface-based CO2 data, using a single inversion system. The five math formula datasets are available in raw and bias-corrected versions, and we found that the bias corrections diminish the range of the five coincident values by ~30% on average. The departures of the five individual inversion results (annual-mean regional fluxes based on math formula-surface combined data) from the surface-data-only results were close to one another in some terrestrial regions where spatial coverage by each math formula dataset was similar. The mean of the five annual global land uptakes was 1.7 ± 0.3 GtC yr−1, and they were all smaller than the value estimated from the surface-based data alone.