Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements

• Verfasst von: Schepers, Dinand [VerfasserIn]
• Verfasst von: Butz, André [VerfasserIn]
• Titel: Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements
• Titelzusatz: performance comparison of proxy and physics retrieval algorithms
• Verf.angabe: D. Schepers, S. Guerlet, A. Butz, J. Landgraf, C. Frankenberg, O. Hasekamp, J.-F. Blavier, N.M. Deutscher, D.W.T. Griffith, F. Hase, E. Kyro, I. Morino, V. Sherlock, R. Sussmann, and I. Aben
• Fussnoten: Gesehen am 14.01.2019
• Titel Quelle: Enthalten in: Journal of geophysical research / D
• Jahr Quelle: 2012
• Band/Heft Quelle: 117(2012) Artikel-Nummer D10307, 14 Seiten
• ISSN Quelle: 2169-8996
• DOI: doi:10.1029/2012JD017549
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1586205552

Abstract

We compare two conceptually different methods for determining methane column-averaged mixing ratios from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared (SWIR) measurements. These methods account differently for light scattering by aerosol and cirrus. The proxy method retrieves a CO2 column which, in conjunction with prior knowledge on CO2acts as a proxy for scattering effects. The physics-based method accounts for scattering by retrieving three effective parameters of a scattering layer. Both retrievals are validated on a 19-month data set using ground-based at 12 stations of the Total Carbon Column Observing Network (TCCON), showing comparable performance: for the proxy retrieval we find station-dependent retrieval biases from −0.312% to 0.421% of a standard deviation of 0.22% and a typical precision of 17 ppb. The physics method shows biases between −0.836% and −0.081% with a standard deviation of 0.24% and a precision similar to the proxy method. Complementing this validation we compared both retrievals with simulated methane fields from a global chemistry-transport model. This identified shortcomings of both retrievals causing biases of up to 1ings and provide a satisfying validation of any methane retrieval from space-borne SWIR measurements, in our opinion it is essential to further expand the network of TCCON stations.