抄録
The land surface emissivity (LSE) in the thermal infrared (TIR) is an essential parameter in the retrieving the land surface temperature (LST) from space. This paper describes the LSE maps in TIR three bands (centered at 10.4, 11.2 and 12.4 μm) used for retrieving the LST from Himawari-8. Himawari-8, a next-generation geostationary satellite has high spatial and temporal resolutions compared to previous geostationary satellites. Due to these improvements, it is expected that the Himawari-8 LST product contribute to observe small-scale environments in high-frequency. In this study, the LSE is estimated by a semi-empirical method, which is a combination of the classification based method and the normalized difference vegetation index (NDVI) thresholds method. The land cover classification information is taken from the Global Land Cover by National Mapping Organizations version3 (GLCNMO 2013). Material emissivities of soil, vegetation and others are taken from the MODIS UCSB emissivity library and the ASTER spectral library. This method is basically following to Peres and DaCamara (2005) but advanced considerations are added. They are phenology of vegetation, flooding of paddy field, snow/ice coverage and the internal reflections (cavity effect) in the urban area. The average cavity effect on LSE in urban canopy is approximately 0.01, but it reaches 0.02 in built-up area. The sensitivity analysis shows that the total LSE errors for three bands are less than 0.02. The LSE estimation is especially stable at the vegetation area, where the error is less than 0.01.
