This web page "JAXA Realtime Rainfall Watch (GSMaP_NOW)" is a quasi-realtime version of "JAXA Global Rainfall Watch (GSMaP_NRT)", which provides global rainfall map 4-hour after observation.
GSMaP_NOW produces rainfall map over the area of geostationary satellite "Himawari", using passive microwave observations that are available within half-hour after observation (GMI, AMSR2 near Japan, and AMSU direct receiving data). Furthermore, half-hour extrapolation of rainfall map toward future direction by using cloud moving vector from the geostationary satellite allows us to estimate "current" rainfall map at every half-hour.
Please note followings when you use GSMaP_NOW data. Since GSMaP_NOW uses less passive microwave radiometer data as input compared to that of GSMaP_NRT, its data accuracy tends to be worse qualitatively. Further more, GSMaP_NOW at "current hour" is estimated by extrapolating half-hour by cloud moving vector, so data accuracy may become worse.
Early validation result of data accuracy of GSMaP_NOW is available from here.
To use data, user registration is needed. If you have already registered as user of the GSMaP_NRT (JAXA Global Rainfall Watch), you can download GSMaP_NOW data from the same ftp server. If you have not registered yet, please make registration from the button below.