Global Terrestrial Ecosystem Carbon Flux Inferred from TanSat XCO2 Retrievals

TanSat is China’s first greenhouse gases observing satellite. In recent years, substantial progresses have been achieved on retrieving column-averaged CO2 dry air mole fraction (XCO2). However, relatively few attempts have been made to estimate terrestrial net ecosystem exchange (NEE) using TanSat XCO2 retrievals. In this study, based on the GEOS-Chem 4D-Var data assimilation system, we infer the global NEE from April 2017 to March 2018 using TanSat XCO2.  Evaluations against independent CO2 observations and comparison with previous estimates indicate that the inverted land sinks in the northern middle latitudes and southern temperate regions are improved to a certain extent, however, they are obviously overestimated in northern high latitudes and underestimated in tropical lands (mainly northern Africa), respectively. 

There are 4 monthly mean variables in this dataset, including prior NEE, posterior NEE, prior ocean flux, and posterior ocean flux, which are all in a spatial resolution of 5 deg by 4 deg.