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The Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core spacecraft is being
developed by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications
Technology (NICT). The GPM is a follow-on mission of the Tropical Rainfall Measuring Mission (TRMM). The objectives of the GPM mission are to observe global precipitation more frequently and accurately than TRMM. The frequent precipitation measurement about every three hours will be achieved by some constellation satellites with microwave radiometers (MWRs) or microwave sounders (MWSs), which will be developed by various countries. The accurate measurement of precipitation in mid-high latitudes will be achieved by the DPR. The GPM core satellite is a joint product of National Aeronautics and Space Administration (NASA), JAXA and NICT. NASA is developing the satellite bus and the GPM microwave radiometer (GMI), and JAXA and NICT are developing the DPR. JAXA and NICT are developing the DPR through procurement. The contractor for DPR is NEC TOSHIBA Space Systems, Ltd. The configuration of precipitation measurement using an active radar and a passive radiometer is similar to TRMM. The major difference is that DPR is used in GPM instead of the precipitation radar (PR) in TRMM. The inclination of the core spacecraft is 65 degrees, and the flight altitude is about 407 km. The non-sun-synchronous circular orbit is necessary for measuring the diurnal change of rainfall similarly to TRMM. The DPR consists of two radars, which are Ku-band (13.6 GHz) precipitation radar (KuPR) and Ka-band (35.55 GHz) precipitation radar (KaPR). According to the different detectable dynamic ranges, The KaPR will detect snow and light rain, and the KuPR will detect heavy rain. In an effective dynamic range in both KuPR and KaPR, drop size distribution information and more accurate rainfall estimates will be provided by a dual-frequency algorithm. The proto-flight test for DPR have finished in February 2012 and DPR integration on GPM core spacecraft was successfully completed in May 2012. The status of proto-flight model of DPR will be presented.
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