Four years of global carbon cycle observed from the Orbiting Carbon Observatory 2 (OCO-2) version 9 and in situ data and comparison to OCO-2 version 7

Hélène Peiro (1) , Sean Crowell (1) , Andrew Schuh (2) , David F Baker (2) , Chris O'Dell (2) , Andrew R Jacobson (3, 4) , Frederic Chevallier (5, 6) , Junjie Liu (7) , Annmarie Eldering (7) , David Crisp (7) , Feng Deng (8) , Brad Weir (9) , Sourish Basu (9) , Matthew S Johnson (10) , Sajeev Philip (9) , Ian Baker (11)

1 OU - University of Oklahoma
2 CIRA - Cooperative Institute for Research in the Atmosphere
3 CIRES - Cooperative Institute for Research in Environmental Sciences
4 NOAA - National Oceanic and Atmospheric Administration
5 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
6 SATINV - Modélisation INVerse pour les mesures atmosphériques et SATellitaires
7 JPL - Jet Propulsion Laboratory
8 University of Toronto
9 GSFC - NASA Goddard Space Flight Center
10 ARC - NASA Ames Research Center
11 CSU - Colorado State University [Fort Collins]

The Orbiting Carbon Observatory 2 (OCO-2) satellite has been providing information to estimate carbon dioxide (CO 2) fluxes at global and regional scales since 2014 through the combination of CO 2 retrievals with top-down atmospheric inversion methods. Column average CO 2 dry-air mole fraction retrievals have been constantly improved. A bias correction has been applied in the OCO-2 version 9 retrievals compared to the previous OCO-2 version 7r improving data accuracy and coverage. We study an ensemble of 10 atmospheric inversions all characterized by different transport models, data assimilation algorithms, and prior fluxes using first OCO-2 v7 in 2015-2016 and then OCO-2 version 9 land observations for the longer period 2015-2018. Inversions assimilating in situ (IS) measurements have also been used to provide a baseline against which the satellite-driven results are compared. The time series at different scales (going from global to regional scales) of the models emissions are analyzed and compared to each experiment using either OCO-2 or IS data. We then evaluate the inversion ensemble based on the dataset from the Total Carbon Column Observing Network (TCCON), aircraft, and in situ observations, all independent from assimilated data. While we find a similar constraint of global total carbon emissions between the ensemble spread using IS and both OCO-2 retrievals, differences between the two retrieval versions appear over regional scales and particularly in tropical Africa. A difference in the carbon budget between v7 and v9 is found over this region, which seems to show the impact Published by Copernicus Publications on behalf of the European Geosciences Union. 1098 H. Peiro et al.: Four years of global carbon cycle observed from OCO-2 version 9 and in situ data of corrections applied in retrievals. However, the lack of data in the tropics limits our conclusions, and the estimation of carbon emissions over tropical Africa require further analysis.

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

Hélène Peiro, Sean Crowell, Andrew Schuh, David F Baker, Chris O'Dell, et al.. Four years of global carbon cycle observed from the Orbiting Carbon Observatory 2 (OCO-2) version 9 and in situ data and comparison to OCO-2 version 7. Atmospheric Chemistry and Physics, 2022, 22 (2), pp.1097 - 1130. ⟨10.5194/acp-22-1097-2022⟩. ⟨hal-03542536⟩