GPM Core Observatory

The GPM Core Observatory is the reference satellite for the international Global Precipitation Measurement (GPM) constellation, operated jointly by NASA and JAXA and launched on 27 February 2014 from Tanegashima Space Center.^[1] It occupies a non-sun-synchronous low Earth orbit at 65-degree inclination, providing coverage of precipitation across the tropics and mid-latitudes; in November 2023 the orbit was raised to approximately 442 km to extend the satellite's operational life into the 2030s.^[2] The two primary instruments are the GPM Microwave Imager (GMI), a conical-scan radiometer operating across 13 channels from 10 to 183 GHz with a swath of 885 km^[3] to 904 km^[1][2], and the Dual-frequency Precipitation Radar (DPR), a Ku- and Ka-band active instrument that profiles precipitation structure in three dimensions.^[4] Together GMI and DPR enable instantaneous retrieval of precipitation rate, drop size distribution, and snow and ice classification, underpinning the IMERG global merged precipitation product that incorporates data from the broader GPM constellation.^[1]