The Global Precipitation Measurement (GPM) is a follow-on and expanded mission of the current on-going Tropical Rainfall Measuring Mission (TRMM). GPM is one of the earth observation satellite programs, mainly initiated by the Japan Aerospace Exploration Agency (JAXA), the National Institute of Infomation and Communications Technology(NICT) and the National Aeronautics and Space Administration (NASA).

  GPM is, like TRMM, composed of one sun non-synchronous orbit satellite (a core satellite)-borne a precipitation radar and a microwave scanning radiometer, and more than one sun synchronous orbit satellite-borne a microwave scanning radiometer (constellation of sub-satellites).

GPM Concept

  The core satellite is expected to be able to measure detailed precipitation activities, using both ofthe dualfrequency precipitation radar and the microwave scanning radiometer. The data acquired by such measurement will permit of sophisticating the presumed algorithm of quantitative rain measurement in the microwave scanning radiometer. The sub-satellite will conduct the precipitation measurement of the microwave scanning radiometer and the measurement will become more reliable by utilizing the presumed algorithm.

  The sub-satellite constellation will be launched by NASA. European Space Agency (ESA) and other space organizations in the world. The number of satellites will be around eight. lt is possible to get a global rainfall distribution in every 3 hours when the microwave scanning radiometers aboard these 8 polar orbit satellites collect and process the data. GPM plans real-time transmission of the global rainfall distribution data. This real-time data can be utilized not only for scientific research, but for social flelds, including weather forecast, flood prediction, water resource management.