Comparisons of OCO-2 satellite derived XCO2 with in situ and modeled data over global ocean

Atmospheric CO2 is one of key parameters to estimate air-sea CO2 flux. The Orbiting Carbon Observatory-2 (OCO-2) satellite has observed the column-averaged dry-air mole fractions of global atmospheric carbon dioxide (XCO2) since 2014. In this study, the OCO-2 XCO2 products were compared between in-situ data from the Total Carbon Column Network (TCCON) and Global Monitoring Division (GMD), and modeling data from CarbonTracker2019 over global ocean and land. Results showed that the OCO-2 XCO2 data are consistent with the TCCON and GMD in situ XCO2 data, with mean absolute biases of 0.25×10−6 and 0.67×10−6, respectively. Moreover, the OCO-2 XCO2 data are also consistent with the CarbonTracker2019 modeling XCO2 data, with mean absolute biases of 0.78×10−6 over ocean and 1.02×10−6 over land. The results indicated the high accuracy of the OCO-2 XCO2 product over global ocean which could be applied to estimate the air-sea CO2 flux.