Seasonal Global Precipitation Variation from the Global Precipitation Measurement Constellation

The Global Precipitation Meaurement (GPM) mission produces NASA's most comprehensive estimate of global rain and snowfall, the Integrated Multi-satellite Retrievals for GPM, or IMERG. IMERG is largely based on data from the GPM constellation - a group of satellites independently operated by many agencies that pool their data for global precipitation estimates. These satellites currently include the GPM Core Observatory, other U.S. civilian satellites (Aqua, NOAA-19, NOAA-20, Suomi NPP), U.S. defense satellites (DMSP F-16, DMSP F-17, DMSP- F18), and international agency satellites (GCOM-W1, Metop-B, Metop-C, and MeghaTropiques). The IMERG dataset starts in June 2000, providing a sufficiently long record that seasonal/regional averages, or climatology, can be computed with reasonable confidence. By comparing the progression of the observed precipitation with climatology, we can generate maps of showing how much observations depart from normal. In the animation, each day's variation from the average precipitation is added to the map, then allowed to gradually fade away over three months so that time changes in the larger-scale patterns are easier to see. Researchers sometimes refer to these deviations from the climatology as "precipitation anomalies".