GHG-CCI: Validation of CO2 and CH4, SCIAMACHY and GOSAT Retrieval Algorithm Products
Dils, Bart¹; Notholt, J.²; Buchwitz, M.²; Boesch, H.³; De Mazière, M.¹; Aben, I.⁴; Armante, R.⁵; Bergamaschi, P.⁶; Blumenstock, T.⁷; Bovensmann, H.²; Brunner, D.⁸; Buchmann, B.⁸; Burrows, J.P.²; Butz, A.⁷; Chédin, A.⁵; Chevallier, F.⁹; Crevoisier, C.D.⁵; Deutscher, N.²; Frankenberg, C.¹⁰; Guerlet, S.⁵; Hasekamp, O.P.⁴; Heymann, J.²; Kaminski, T.¹¹; Laeng, A.⁷; Lichtenberg, G.¹²; Noël, S.²; Orphal, J.⁷; Parker, R.³; Popp, C.⁸; Reuter, M.²; Schneising, O.²; Scholze, M.¹¹; Sussmann, R.⁷; Stiller, G.P.⁷; Warneke, T.²; Zehner, C.¹³; Bril, A.¹⁴; Crisp, D.¹⁰; Griffith, D.¹⁵; Kuze, A.¹⁶; O'Dell, C.¹⁷; Oshchepkov, S.¹⁴; Sherlock, V.¹⁸; Suto, H.¹⁶; Wennberg, P.¹⁹; Wunch, D.¹⁹; Yokota, T.¹⁴; Yoshida, Y.^14
1Belgian Institute for Space Aeronomy (BIRA-IASB), BELGIUM; ²Institute of Environmental Physics (IUP), University of Bremen, GERMANY; ³University of Leicester, UNITED KINGDOM; ⁴SRON Netherlands institute for Space Research, NETHERLANDS; ⁵Laboratoire de Météorologie Dynamique (LMD), FRANCE; ⁶European Commission Joint Research Centre (EC-JRC), ITALY; ⁷Karlsruhe institute of Technology (KIT), GERMANY; ⁸Swiss Federal Laboratories for Materials Science and Technology (Empa), SWITZERLAND; ⁹laboratoire des Sciences du Climate et de l'Environment (LSCE), FRANCE; ¹⁰Jet Propulsion Laboratory (JPL), UNITED STATES; ¹¹FastOpt, GERMANY; ¹²Deutsches Zentrum für Luft- und Raumfahrt (DLR), GERMANY; ¹³European Space Agency (ESA), SRIN, ITALY; ¹⁴National Institute for Environmental Studies (NIES), JAPAN; ¹⁵University of Wollongong, AUSTRALIA; ¹⁶Japan Aerospace Exploration Agency (JAXA), JAPAN; ¹⁷Colorado State University (CSU), UNITED STATES; ¹⁸National Institute of Water and Atmospheric Research (NIWA), NEW ZEALAND; ¹⁹California Institute of Technology, UNITED STATES

Within the framework of the European Space Agency's (ESA) Greenhouse Gas Climate Change Initiative (GHG-CCI) project, column-averaged volume mixing ratios of carbon dioxide and methane derived by several European retrieval algorithms from the TANSO-FTS and SCIAMACHY instruments on board GOSAT and ENVISAT, are being developed so as to obtain a dedicated Essential Climate Variable (ECV), which meets the stringent quality requirements set forward by the user community. The project consists of several development and validation phases. The first so-called Round-Robin validation phase, already eliminated several competing algorithms from the ECV development process. Those that are still in the running have been added to the GHG-CCI Climate Research Data Package (CRDP). These are, for SCIAMACHY XCH4, both the Weighting Function Modified Differential Optical Absorption Spectroscopy(DOAS) algorithm (WFMD, University of Bremen) and the Iterative Maximum A Posteriori DOAS (IMAP, Netherlands Institute for Space Research (SRON) and Jet Propulsion Laboratory (JPL)), for SCIAMACHY XCO2 we have the Bremen Optimal Estimation DOAS (BESD, University of Bremen) algorithm. For GOSAT XCH4 we have the proxy version of the University of Leicester’s adaptation of the OCO (Orbiting Carbon Observatory) algorithm (OCPR) and the full physics version of the RemoteC algorithm (SRFP) developed by SRON. For GOSAT XCO2 the differences during the project's so-called Round Robin validation round between the SRON and Leicester Full Physics algorithms (OCFP and SRFP) were small but significant, therefore more studies are needed and both have been added to the data package. Additionally the EnseMble Median Algorithm (EMMA, University of Bremen), which makes use of all available XCO2 algorithms, was added to make optimal use of the available data. All these algorithms have been compared with ground based Fourier Transform Spectroscopy (FTS) measurements from the Total Carbon Column Observing Network (TCCON) and the Network for the Detection of Atmospheric Composition Change (NDACC), to see if a further selection can be made and/or the quality requirements are met. Here we will discuss the current status of this GHG-CCI CRDP validation-phase and the results obtained therein.