The Global Precipitation Measurement (GPM) Microwave Imager (GMI) Rain Rate (Ascending) layer provides the rate at with rain reaches the earth's surface in millimeters per hour (mm/hr). The Rain Rate layer provides snapshots of individual storms, including tropical cyclones and flood-producing systems.

The GPM Microwave Imager (GMI) has a total of 13 channels, each observing the earth at a different frequency (10-183 GHz) or at a different polarization (vertical or horizontal). Each channel measures the natural emission from the earth's surface, atmospheric gases, and precipitation. GMI sees through the tops of clouds to observe how much and where precipitation occurs. The lower frequency GMI channels respond more directly to rain, while the higher frequency GMI channels respond to the higher-altitude ice precipitation that is often associated with vigorous rain rates near the earth's surface.

GMI is an instrument on the satellite known as the Global Precipitation Measurement (GPM) Core Observatory. The parent data product for the Rain Rate layer is the 2AGPROFGMI data product, which is also known as "Level 2A Goddard Profiling algorithm" or as "GPM_2AGPROFGPMGMI". The imagery resolution is 2 km and sensor resolution is approximately 4 km at the equator, and the rain estimates are reported on footprints that are approximately 6 km across. The temporal resolution is daily.

References: GES DISC: GPM_2AGPROFGPMGMI; GPM Explores Hurricane Gonzalo; Precipitation Processing System; Global Precipitation Measurement (GPM) Mission Algorithm Theoretical Basis Document