The seasonal cycle of atmospheric CO2 in Australia over the last ten years seen by GOSAT
Eva-Marie Schömann, Heidelberg University, eschoema@iup.uni-heidelberg.de (Presenter)
Sourish Basu, NASA GSFC GMAO / University of Maryland, sourish@umd.edu
Sanam N. Vardag, Heidelberg University, svardag@iup.uni-heidelberg.de
Lena Schreiner, Heidelberg University, lena.schreiner@iup.uni-heidelberg.de
Andre Butz, Heidelberg University, andre.butz@iup.uni-heidelberg.de
In the southern hemisphere, the sparse coverage of in-situ CO2 measurements prevents a robust determination of regional carbon fluxes and leads to large uncertainties in inverse model results. Therefore, the extensive spatial coverage afforded by satellite CO2 measurements is especially valuable there. By analyzing satellite measurements, new insights on the carbon cycle can be derived and carbon cycle models can be validated for the southern hemisphere.
Here, we present a comparison of atmospheric CO2 data in Australia provided by the Greenhouse gases Observing SATellite (GOSAT) and inverse model systems such as CarbonTracker (CT2019) and TM5-4DVar from 2009 to 2018. We find that the seasonality of GOSAT CO2 is different from that of the inverse models using in-situ data across much of the southern hemisphere. The discrepancy between GOSAT and the models follows a clear seasonal pattern with the largest difference of ~2ppm between October and December. We investigate the origin of the discrepancy using different fire CO2 emission databases and FLUXCOM net ecosystem exchange of CO2. Further, we assimilate GOSAT CO2 in the TM5-4DVar data assimilation system to pinpoint the origin of CO2 fluxes. Our results suggest that an underestimation of local and transported wildfire CO2 emissions as well as underestimated biospheric CO2 fluxes could cause the observed discrepancy in the seasonality of column CO2 between GOSAT and inverse models in Australia.
Presentation: Talk_Schmann_27_25.pdf
Presentation Type: Talk
Session: 3.4 Flux estimates and atmospheric inversions from space-based GHG measurements
Session Date: Wednesday (6/16) 11:15 AM