Carbon dioxide retrieval from OCO-2 satellite observations using the RemoTeC algorithm and validation with TCCON measurements
journal contribution
posted on 2024-11-15, 01:47 authored by Lianghai Wu, Otto Hasekamp, Haili Hu, Jochen Landgraf, Andre Butz, Joost aan de Brugh, Ilse Aben, David F Pollard, David GriffithDavid Griffith, Dietrich G Feist, Dmitry Koshelev, Frank Hase, Geoffrey Toon, Hirofumi Ohyama, Isamu Morino, Justus Notholt, Kei Shiomi, Laura T Iraci, Matthias Schneider, Martine De Maziere, Ralf Sussmann, Rigel Kivi, Thorsten Warneke, Tae-Young Goo, Yao TeIn this study we present the retrieval of the column-averaged dry air mole fraction of carbon dioxide (X CO2 ) from the Orbiting Carbon Observatory-2 (OCO-2) satellite observations using the RemoTeC algorithm, previously successfully applied to retrieval of greenhouse gas concentration from the Greenhouse Gases Observing Satellite (GOSAT). The X CO2 product has been validated with collocated ground-based measurements from the Total Carbon Column Observing Network (TCCON) for almost 2 years of OCO-2 data from September 2014 to July 2016. We found that fitting an additive radiometric offset in all three spectral bands of OCO-2 significantly improved the retrieval. Based on a small correlation of the XCO2 error over land with goodness of fit, we applied an a posteriori bias correction to our OCO-2 retrievals. In overpass averaged results, XCO2 retrievals have an SD of ∼ 1.30 ppm and a station-to-station variability of ∼ 0.40 ppm among collocated TCCON sites. The seasonal relative accuracy (SRA) has a value of 0.52 ppm. The validation shows relatively larger difference with TCCON over high-latitude areas and some specific regions like Japan.