TY - JOUR
T1 - Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements: Performance comparison of proxy and physics retrieval algorithms
AU - Schepers, D.
AU - Guerlet, S.
AU - Butz, A.
AU - Landgraf, J.
AU - Frankenberg, C.
AU - Hasekamp, O.
AU - Blavier, J.-F.
AU - Deutscher, N.M.
AU - Griffith, D.W.T.
AU - Hase, F.
AU - Kyro, E.
AU - Morino, I.
AU - Scherlock, V.
AU - Sussmann, R.
AU - Aben, E.A.A.
PY - 2012
Y1 - 2012
N2 - We compare two conceptually different methods for determining methane column-averaged mixing ratios (XCH4) 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 CO2 acts 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 XCH4 measurements 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 XCH4 with 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. © Copyright 2012 by the American Geophysical Union.
AB - We compare two conceptually different methods for determining methane column-averaged mixing ratios (XCH4) 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 CO2 acts 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 XCH4 measurements 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 XCH4 with 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. © Copyright 2012 by the American Geophysical Union.
UR - https://www.scopus.com/pages/publications/84861707411
UR - https://www.scopus.com/inward/citedby.url?scp=84861707411&partnerID=8YFLogxK
U2 - 10.1029/2012JD017549
DO - 10.1029/2012JD017549
M3 - Article
SN - 2169-897X
VL - 117
JO - Journal of Geophysical Research. Atmospheres
JF - Journal of Geophysical Research. Atmospheres
M1 - D10307
ER -
