Best Water Vapor Information Layer of Himawari-8-Based Water Vapor Bands over East Asia

The best water vapor information layer (BWIL), based on Himawari-8 water vapor bands over a typical region of East Asia, is investigated with the U.S. standard atmospheric profile and European Centre for Medium-Range Weather Forecasts Re-Analysis-interim (ERA-interim) dataset. The sensitivity tests reveal that the height of the BWIL is connected heavily to the amount of water vapor in the atmosphere, and to the satellite zenith angle. According to the temporal and spatial distribution analysis of BWIL, there are two basic features of BWIL. First, it lifts from January to July gradually and descends from July to October in the whole region. Second, it is higher over sea than land. These characteristics may stem from the transport of water vapor by monsoon and the concentration of water vapor in different areas. With multiple water vapor absorption IR bands, Himawari-8 can present water vapor information at multiple pressure layers. The water vapor content of ERA-interim in July 2016 is assessed as an example. By comparing the brightness temperatures from satellite observation and simulation under clear sky conditions, the ERA-interim reanalysis dataset may underestimate the amount of water vapor at pressure layers higher than 280 hPa and overestimate the water vapor quantity at pressure layers from 394 to 328 hPa, yet perform well at 320~260 hPa during this month.