HR: 0800h
AN: A51C-0788 [Abstracts]
TI: Sensor Specification Demand of a Nadir Looking SWIR FTS Aboard GOSAT to Monitor CO$_2$ Column Density
in the Clear Sky Condition
AU: * Yokota, T
EM: yoko@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AU: Higurashi, A
EM: hakiko@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AU: Oguma, H
EM: oguma@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AU: Morino, I
EM: morino@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AU: Aoki, T
EM: aoki.tadao@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AU: Inoue, G
EM: inouegen@nies.go.jp
AF: National Institute for Environmental Stusies, 16-2 Onogawa, Tsukuba, Inaraki, 305-8506
Japan
AB:
Greenhouse gases Observing Satellite (GOSAT) will be launched in 2008 to monitor column density of green house gases such as
CO$_2$ and CH$_4$ globally. A nadir-looking Fourier-Transform Spectrometer (FTS) which covers Short Wavelength Infrared
(SWIR; 1.6 $\mu$m and 2.0 $\mu$m) and 0.76 $\mu$m oxygen A-band regions will be mounted on GOSAT. The 1.64 $\mu$m absorption
band of CH$_4$ is used to estimate methane density. The SWIR FTS will measure surface scattered and sun-glint solar light.
National Institute for Environmental Studies (NIES) has been carrying out researches on sensitivity and error analyses, data
retrieval algorithm study, ground-based/air-borne validation measurements, and a plan of inverse model study to estimate
distribution of source/sink amount of CO$_2$ in sub-continental scale.
The possible error sources for estimating CO$_2$ and CH$_4$ column density are aerosols, cirrus clouds, water vapor, surface
pressure (altitude), broken clouds, surface albedos, line parameters of absorption gases. Among them, aerosols and cirrus
clouds are major error sources because they would affect baseline variations in measured radiances and distort gas absorption
spectra. Portion of broken clouds in the FTS field of view will be estimated with a GOSAT aerosol-cloud imager. A minimum
criterion of the GOSAT project is to observe spectra and estimate CO$_2$ column density within 1% error at least in the
clear sky condition. According to our numerical simulation test results, we recommend that the specification demand of the
GOSAT SWIR FTS should be a finer spectral resolution of 0.2 cm$^{-1}$ and a larger signal to noise ratio of 300. The reasons
why we have recommended this specification will be presented here.
DE: 1610 Atmosphere (0315, 0325)
DE: 1640 Remote sensing
DE: 0360 Transmission and scattering of radiation
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting