Improvement of the retrieval algorithm for GOSAT SWIR XCO2and XCH4and their validation using TCCON data by Yoshida, Y, Kikuchi, N, Morino, I, Uchino, O, Oshchepkov, S, Bril, A, Saeki, T, Schutgens, N, Toon, G, Wunch, D, Roehl, C, Wennberg, P, Griffith, D, Deutscher, N, Warneke, T, Notholt, J, Robinson, J, Sherlock, V, Connor, B, Rettinger, M, Sussmann, R, Ahonen, P, Heikkinen, P, Kyrö, E, Mendonca, J