NASA’s Precipitation Measurement Missions (PMM) have collected rain and snowfall from space for nearly 20 years, and for the first time in 2019, scientists can access PMM’s entire record as one data set.
PMM includes two missions – the Tropical Rainfall Measuring Mission (TRMM), which orbited Earth from 1997 to 2015, and its successor, the joint NASA-JAXA Global Precipitation Measurement mission (GPM), which has been collecting data since 2014. This year, however, the GPM project upgraded its data algorithms to calibrate and incorporate TRMM data into its release, giving researchers, modelers and meteorologists access to the entire 19-year record.
By being able to compare and contrast past and present data, researchers are better informed to make climate and weather models more accurate, better understand normal and extreme rain and snowfall around the world, and strengthen applications for current and future disasters, disease, resource management, energy production and food security.
GPM provides a four-dimensional view of rain, snow, sleet and storms from space: It not only records the size of droplets or pellets, but how heavy the precipitation is and how it changes over time. This perspective is used not only for global science, like studying Earth’s water and energy cycles and spotting extreme weather around the world, but it is also useful for studying single events, like hurricanes or droughts.
GPM’s signature algorithm is the Integrated Multi-satellitE Retrievals for GPM, or IMERG. IMERG calibrates and combines data from its main satellite, the GPM Core Observatory, and the GPM Constellation, a group of international satellites that contribute data to GPM while also performing their own missions. While the full IMERG product takes time to process and prepare, it also generates a near-real-time summary of global precipitation every half-hour, which is useful for time-sensitive applications like weather forecasting and disaster recovery.
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