Preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from GOSAT short-wavelength infrared spectra

Column-averaged volume mixing ratios of carbon dioxide and methane retrieved from the Greenhouse gases Observing SATellite (GOSAT) Short-Wavelength InfraRed observation (GOSAT SWIR X-CO2 and X-CH4) were compared with the reference calibrated data obtained by ground-based high-resolution Fourier Transform Spectrometers (g-b FTSs) participating in the Total Carbon Column Observing Network (TCCON). Preliminary results are as follows: the GOSAT SWIR X-CO2 and X-CH4 (Version 01.xx) are biased low by 8.85 +/- 4.75 ppm (2.3 +/- 1.2 %) and 20.4 +/- 18.9 ppb (1.2 +/- 1.1 %), respectively. The standard deviation of the GOSAT SWIR X-CO2 and X-CH4 is about 1% (1 sigma) after correcting the negative biases of X-CO2 and X-CH4 by 8.85 ppm and 20.4 ppb, respectively. The latitudinal distributions of zonal means of the GOSAT SWIR X-CO2 and X-CH4 show similar features to those of the g-b FTS data except for the negative biases in the GOSAT data.