Test measurements by a BBM of the nadir-looking SWIR FTS aboard GOSAT to monitor CO_2 column density from space

摘要

Greenhouse gases Observing SATellite (GOSAT) is a Japanese satellite to monitor column density of greenhouse gases such as carbon dioxide (CO_2) and methane (CH_4) globally from space. GOSAT will be launched in 2008. The data measured by a GOSAT sensor and ground-based monitoring station data will be used into an atmospheric transport inverse model to identify source/sink amount of CO_2 in a sub-continental scale. One of the main GOSAT sensors is a nadir-looking Fourier Transform Spectrometer (FTS), which covers Short Wavelength Infrared (SWIR) region to measure column density of CO_2. National Institute for Environmental Studies (NIES) is promoting researches on CO_2 and CH_4 sensitivity analysis, error analysis, data retrieval algorithm study, ground-based/air-borne validation strategy, and a plan of inverse model study for the SWIR FTS. A Bread-board model (BBM) of the SWIR FTS was built and tested by ground-based and airborne measurements. Several sets of the CO_2 and CH_4 radiance spectra over rice fields were obtained by the test measurements, and it was confirmed that the airborne measurements with a vibration insulator are effective for onboard measurements. Moreover, several improvement items of BBM have become clear.