East-Asia land surface emissivity maps generated from Terra/ASTER data archives

摘要

The Advanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) is a high-spatial-resolution multispectral imager on the Terra satellite launched in December 1999. The ASTER thermal infrared (TIR) subsystem has five spectral bands with a spatial resolution of 90 m in the TIR spectral region, which are used for generation of the standard products of surface temperature and surface spectral emissivity. High-resolution surface emissivity at five spectral bands is unique, and is particularly useful for geological mapping. However, the emissivity product is not always easy to use, because (1) its image size is about 60 km square which is not large enough for regional-scale studies, (2) its imaged area is not fixed to the world reference system (WRS) due to a flexible pointing system, and (3) standard atmospheric correction often fails under humid conditions. Thus, in order to improve the usability of the ASTER emissivity product, we are generating land surface emissivity maps in a regional scale by applying improved retrieval algorithms and stack/mosaic processing to an ASTER orthogonal projection dataset which have been produced from the ASTER data archives by the Advanced Industrial Science and Technology (AIST), Japan. In the present paper, we introduce East-Asia land surface emissivity maps as the first result of this project. A comparison study with MODIS monthly emissivity products (MODI 1C3) indicates that the generated maps give more reasonable emissivity spectra with higher spatial resolution than the MODIS emissivity products, though the maps have missing pixels in high latitude areas and humid areas.