複数の衛星搭載マイクロ波／赤外放射計の複合による「世界の雨分布速報」システムの構築とその利用

As accuracy of satellite precipitation estimates improves and observation frequency increases, the applicability of those data to a more variety of societal benefits as well as climate studies is expected to enhance. To meet those users' needs that higher temporal resolution is desired with near-real-time availability, we are developing and operating the “JAXA Global Rainfall Watch” system, which produces hourly global rainfall map data in 0.1 degree grid resolution, and disseminates it four hours after observation. The algorithms are based on the achievement of the Global Satellite Mapping for Precipitation (GSMaP) project, which combined observation data from microwave and infrared radiometers aboard multiple satellites. The interests of GSMaP users cover broad fields and world wide. Several activities to apply GSMaP data to some flood warning systems are underway. Validation with Japanese Radar-AMeDAS rainfall analysis data for 2009 shows correlation coefficients higher than 0.5 during rainy season, but lower values around 0.3 or 0.4 during winter season with less rainfall. GSMaP is a proto-type for the Global Precipitation Measurement (GPM) mission in 2013, and challenges and possibilities of new application are explored.