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...