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Constraining tropical biosphere CO2 fluxes by simultaneous assimilation of GOSAT Xco2 and AIRS mid-troposphere CO2 observations with variational inversion: a theoretical study
Junjie
Liu, JPL, junjie.liu@jpl.nasa.gov
(Presenter)
Kevin
W
Bowman, JPL, kevin.w.bowman@jpl.nasa.gov
Meemong
Lee, JPL, meemong.lee@jpl.nasa.gov
Daven
Henze, CU, daven.henze@colorado.edu
Edward
Olsen, JPL, edward.t.olsen@jpl.nasa.gov
Due to the lack of conventional CO2 observations, the CO2 flux estimation over the tropical region has large uncertainties. Because of its global observation coverage, CO2 observations observed by satellites provide an opportunity to understand the tropical carbon flux from atmospheric inversion. Greenhouse Gases Observing Satellite (GOSAT) observes column CO2 (Xco2) with sensitivity close to surface. However, GOSAT has very sparse observation coverage over the tropical region due to cloud. There are less then 10 observations over the whole year of 2010 within some 5x4 grid points. On the other hand, CO2 observations from Atmospheric Infrared Sounder (AIRS, launched in 2002) are dense since AIRS overpasses the same point twice per day. Through adjoint sensitivity studies, we found that AIRS CO2 has strong sensitivity to the tropical surface CO2 flux, even though the peak sensitivity of AIRS CO2 is in the middle to upper troposphere. In this study, we investigate the impact of GOSAT Xco2 and AIRS mid-troposphere CO2 over the tropical region on the tropical flux estimation through Observing System Simulation Experiments (OSSEs). We found that assimilating simulated GOSAT Xco2 reduces the tropical monthly CO2 flux uncertainty by about 30%. When both GOSAT observations and AIRS CO2 over the tropical region are assimilated, the accuracy of monthly CO2 flux over the Amazon region has been improved by about 80%. This study indicates that mid-troposphere CO2 provides valuable constraint on CO2 flux estimation where the Xco2 observation coverage is sparse.
Presentation Type: Poster
Session: Poster Session 2-A
(Wed 11:00 AM)
Associated Project(s):
Poster Location ID: 61
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