The First Global Carbon Dioxide Flux Map Derived from TanSat Measurements  

作　　者：Dongxu YANG Yi LIU Liang FENG Jing WANG Lu YAO Zhaonan CAI Sihong ZHU Naimeng LU Daren LYU 

机构地区：[1]Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China [2]National Centre for Earth Observation,University of Edinburgh,Edinburgh,EH93FF,UK [3]University of Edinburgh,Edinburgh,EH93FF,UK [4]National Satellite Meteorological Center,China Meteorological Administration Beijing 100081,China

出　　处：《Advances in Atmospheric Sciences》2021年第9期1433-1443,共11页大气科学进展（英文版）

基　　金：supported by the National Key R&D Program of China (Grant No.2016YFA0600203);the National Key R&D Program of China (Grant No.2017YFB0504000);the Key Research Program of the Chinese Academy of Sciences (ZDRW-ZS-2019-1);the Youth Program of the National Natural Science Foundation of China (Grant No.41905029);supported by the UK NERC National Centre for Earth Observation (NCEO);The TanSat L1B data service is provided by IRCSD and CASA (131211KYSB20180002)。

摘　　要：Space-borne measurements of atmospheric greenhouse gas concentrations provide global observation constraints for top-down estimates of surface carbon flux.Here,the first estimates of the global distribution of carbon surface fluxes inferred from dry-air CO_2 column (XCO_2) measurements by the Chinese Global Carbon Dioxide Monitoring Scientific Experimental Satellite (Tan Sat) are presented.An ensemble transform Kalman filter (ETKF) data assimilation system coupled with the GEOS-Chem global chemistry transport model is used to optimally fit model simulations with the Tan Sat XCO_2 observations,which were retrieved using the Institute of Atmospheric Physics Carbon dioxide retrieval Algorithm for Satellite remote sensing (IAPCAS).High posterior error reduction (30%–50%) compared with a priori fluxes indicates that assimilating satellite XCO_2 measurements provides highly effective constraints on global carbon flux estimation.Their impacts are also highlighted by significant spatiotemporal shifts in flux patterns over regions critical to the global carbon budget,such as tropical South America and China.An integrated global land carbon net flux of 6.71±0.76 Gt C yr^(-1) over12 months (May 2017–April 2018) is estimated from the Tan Sat XCO_2 data,which is generally consistent with other inversions based on satellite data,such as the JAXA GOSAT and NASA OCO-2 XCO_2 retrievals.However,discrepancies were found in some regional flux estimates,particularly over the Southern Hemisphere,where there may still be uncorrected bias between satellite measurements due to the lack of independent reference observations.The results of this study provide the groundwork for further studies using current or future Tan Sat XCO_2 data together with other surfacebased and space-borne measurements to quantify biosphere–atmosphere carbon exchange.

关 键 词：TanSat carbon flux CO_2 flux inversion 

分 类 号：X16[环境科学与工程—环境科学]