Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020)

Here we present a global and regionally-resolved terrestrial net biosphere exchange30 (NBE) dataset with corresponding uncertainties between 2010–2018: CMS-Flux NBE 2020. It is31 estimated using the NASA Carbon Monitoring System Flux (CMS-Flux) top-down flux32 inversion system that assimilates column CO2 observations from the Greenhouse gases33 Observing SATellite (GOSAT) and NASA’s Observing Carbon Observatory -2 (OCO-2). The34 regional monthly fluxes are readily accessible as tabular files, and the gridded fluxes are35 available in NetCDF format. The fluxes and their uncertainties are evaluated by extensively36 comparing the posterior CO2 mole fractions with CO2 observations from aircraft and the NOAA37 marine boundary layer reference sites. We describe the characteristics of the dataset as global38 total, regional climatological mean, and regional annual fluxes and seasonal cycles. We find that39 the global total fluxes of the dataset agree with atmospheric CO2 growth observed by the surface40observation network within uncertainty. Averaged between 2010 and 2018, the tropical regions41 range from close-to neutral in tropical South America to a net source in Africa; these contrast42 with the extra-tropics, which are a net sink of 2.5 ± 0.3 gigaton carbon per year. The regional43 satellite-constrained NBE estimates provide a unique perspective for understanding the terrestrial44 biosphere carbon dynamics and monitoring changes in regional contributions to the changes of45 atmospheric CO2 growth rate. The gridded and regional aggregated dataset can be accessed at:46 https://doi.org/10.25966/4v02-c391 (Liu et al., 2020).