HR: 0800h
AN: A21D-0903    [Abstracts]
TI: Error Estimation of CO₂ and CH₄ Column Amount Retrieval Using Synthetic Data of the GOSAT SWIR FTS: A Method to Overcome the Wavelength Dependency of Ground Surface Albedos
AU: * Ishihara, H
EM: hironari@ilas2.nies.go.jp
AF: Fujitsu FIP Corporation, 2-45 Aomi, Koto-ku, Tokyo, 135-8686 Japan
AU: Kotani, A
EM: kotani@ilas2.nies.go.jp
AF: Fujitsu FIP Corporation, 2-45 Aomi, Koto-ku, Tokyo, 135-8686 Japan
AU: Uemura, N
EM: uemura@ilas2.nies.go.jp
AF: Fujitsu FIP Corporation, 2-45 Aomi, Koto-ku, Tokyo, 135-8686 Japan
AU: Nobuta, K
EM: nobuta@ilas2.nies.go.jp
AF: Fujitsu FIP Corporation, 2-45 Aomi, Koto-ku, Tokyo, 135-8686 Japan
AU: Yokota, T
EM: yoko@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Higurashi, A
EM: hakiko@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Morino, I
EM: morino@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Oguma, H
EM: oguma@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Aoki, T
EM: aoki.tadao@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Inoue, G
EM: inouegen@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: In order to estimate the errors of CO₂ and CH₄ column amounts retrieved from the measurement by using a SWIR (Short Wavelength InfraRed) FTS sensor aboard GOSAT (Greenhouse gases Observing Satellite), various error sources should be taken into account. Some possible error sources are aerosols, cirrus cloud, water vapor, surface pressure (altitude), wavelength dependency of ground surface albedos, temperature profile, radiometric sensitivity of detectors, and the absorption line parameters of gases. In this study, we have performed sensitivity studies and error analyses on the impact of wavelength dependency of ground surface albedos. Ground surface albedos have various wavelength dependences, which correspond to the surface conditions such as vegetation, soil, etc. The SWIR FTS sensor will perform nadir looking observations of sunlight scattered by ground surface. The measurement spectral regions are 2.0 micron band (4800 - 5200 cm^-1), 1.6 micron band (5800 - 6400 cm^-1), and 0.76 micron band (12900 - 13200 cm^-1). Each band width is broad, hence it is important for the column amount estimation of CO₂ and CH₄ that the wavelength dependence of surface albedos within each spectral region is correctly estimated. We have simulated radiance data for several surface albedos with different wavelength dependency in a clear sky condition, and have tried to retrieve CO₂ and CH₄ profiles and the ground surface albedos. In case of assuming ground surface albedos as a constant within each band in retrieval, the column amount retrieval error affected by the wavelength dependency of ground surface albedos was large. By assuming the spectrum of ground surface albedos in each band by a polygonal line with knots at every several ten wavenumbers, the error became considerably reduced.
DE: 0360 Radiation: transmission and scattering
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005