The Effect of GOSAT Observations on Estimates of Net CO₂ Flux in Semi-Arid Regions of the Southern Hemisphere

Abstract

Greenhouse gases Observing SATellite (GOSAT) is the operational satellite dedicated to atmospheric CO 2 observations. Assimilation of data provided by GOSAT is expected to yield reliable CO 2 fluxes in semi-arid regions because of frequent observations owing to clear skies. Here we estimated net CO 2 flux over semi-arid regions of the Southern Hemisphere using the GOSAT column averaged CO 2 (X CO2 ) and surface CO 2 measurements. Assimilation of GOSAT X CO2 indicated that semi-arid regions are integral components of recent terrestrial CO 2 uptake, accounting for 44% globally. Compared with estimates assimilated from surface measurements, estimates by GOSAT X CO2 suggest a 50% reduction in the semi-arid CO 2 uptake, amounting to 1.1 Pg C yr −1 . Significant estimation differences occurred for South America and South Africa, where the GOSAT makes frequent measurements but where surface CO 2 measurements are limited. In comparison, the two estimates varied less in Australia, where more surface measurements are available. These results suggest that GOSAT X CO2 is effective at regulating excess estimates of semi-arid CO 2 uptake in regions that are less constrained by surface CO 2 measurements. To promote understanding of climate change effects in semi-arid regions, it is important to continue monitoring trends in CO 2 uptake with GOSAT.(Citation: Kondo, M., T. Saeki, H. Takagi, K. Ichii, and K. Ishijima, 2016: The effect of GOSAT observations on estimates of net CO 2 flux in semi-arid regions of the Southern Hemisphere.

Bridge to the future: Important lessons from 20 years of ecosystem observations made by the OzFlux network

“…to the carbon sink due to human mitigation efforts or responses of the biosphere to prior events?). (NBP) from the natural biosphere (Buchwitz et al, 2017;Kondo et al, 2016).…”

“…They analysed the hydroclimate drivers and pulse response behaviour of carbon fluxes during the big wet and reported that semi‐arid Australian net CO 2 uptake was highly transient and rapidly dissipated by subsequent drought. The accuracies of the remotely sensed CO 2 retrievals and the atmospheric transport models are approaching the levels needed to constrain CO 2 fluxes to estimate net biome productivity (NBP) from the natural biosphere (Buchwitz et al, 2017; Kondo et al, 2016).…”