113 ADEOS衛星搭載IMGセンサーにより観測されたメタンと一酸化炭素の全球分布

Abstract

Interferometric Monitor for Greenhouse gases (IMG) is a Fourier Transform Spectrometer (FTS) which has been developed for measuring greenhouse gases in the atmosphere, particularly in the troposphere. It was operated for about 7 months from November 1996 to the end of June 1997. During the operational period IMG measured over 23000 terrestrial thermal emission spectra of which the signal to nose ratio was sufficient for retrieving atmospheric parameters such as temperature and gas concentrations. The most serious problem in measuring tropospheric gases using an infrared spectrometer is the cloud contamination. We used a cloud detection and correction (screening) method which was based on the analysis of the initially retrieved temperature profiles for retrieving temperature and gas profiles. Preliminary results on global distribution of methane and carbon monoxide were obtained using the cloud detection method. However the results were seemed to be contaminated with clouds even after the cloud correction (screening) process particularly in the polar regions. We need more effective cloud detection method using visible and near-infrared imagery that was simultaneously obtained with IMG data such as those from OCTS (Ocean Color and Temperature Scanner) for raising the accuracy of the retrieval.