The work by FJT was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. VL acknowledges support from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 603608, Global Earth Observation for integrated water resource assessment: eartH2Observe. Levizzani https://orcid. org/0000-0002-7620-5235 C. Kidd https://orcid. org/0000-0001-5906-8446 ORCID HRPP High-Resolution Precipitation Product V. H SAF Satellite Application Facility on Support to Operational Hydrology and Water Management ICWG International Clouds Working Group IFloods Iowa Flood Season campaign IGeoLab International Geostationary Laboratory IMERG Integrated Multi-satelliteE Retrievals for GPM IPHEx Integrated Precipitation and Hydrology Experiment IPWG International Precipitation Working Group IR InfraRed IROWG International Radio Occultation Working Group ISRO Indian Space Research Organisation ISWGs International Science Working Groups (CGMS) ITWG International TOVS Working Group IWSSM International Workshop on Space-based Snowfall Measurement IWWG International Winds Working Group JCSDA Joint Centre for Satellite Data Assimilation JMA Japan Meteorological Agency JPSS Joint Polar Satellite System KMA Korea Meteorological Administration LI Lightning Imager LPVEX Light Precipitation Validation Experiment MHS Microwave Humidity Sounder MSWEP Multi-Source Weighted-Ensemble Precipitation GLOSSARY MTG MTGV Meteosat Third Generation Megha-Tropiques Ground Validation AIP Algorithm Intercomparison Programme MW MicroWave AMSR-E Advanced Microwave Scanning Radiometer for the NAS National Academy of Sciences Earth Observing System NASA National Aeronautics and Space Administration AMSU-B Advanced Microwave Sounding Unit-B NPOESS National Polar-orbiting Operational Environmental APSATS Asia-Pacific Satellite Applications Training Seminar Satellite System ATMS Advanced Technology Microwave Sounder NPP NPOESS Preparatory Project BoM Bureau of Meteorology (Australia) OceanRAIN Ocean Rainfall And Ice-phase precipitation measure- CCI Climate Change Initiative (ESA) ment Network CGMS Coordination Group for Meteorological Satellites OLYMPEx Olympic Mountains Experiment CMA China Meteorological Administration OSCAR Observing Systems Capability Analysis and Review CM SAF Satellite Application Facility on Climate Tool Monitoring PEHRPP Program for the Evaluation of High Resolution Precipi- C3S Copernicus Climate Change Service tation Products DMSP Defense Meteorological Satellite Program PIP-x Precipitation Intercomparison Project-x ESA European Space Agency PMW Passive MicroWave eTRaP Ensemble TRaP RainCube Radar in a CubeSat EUMETSAT European Organization for the Exploitation of SM2RAIN Soil Moisture to Rain Meteorological Satellites SSM/I Special Sensor Microwave/Imager FCDR Fundamental Climate Data Record SSMI/S Special Sensor Microwave/Imager/Sounder GCOM-W Global Change Observation Mission-Water TEMPEST Temporal Experiment for Storms and Tropical Systems GCOS Global Climate Observing System TRaP Tropical Rainfall Potential GCPEX GPM Cold Season Precipitation Experiment TROPICS Time Resolved Observations of Precipitation Structure GEWEX Global Energy and Water cycle EXchanges and Storm Intensity with a Constellation of Smallsats GLM Geostationary Lightning Mapper TRMM Tropical Rainfall Measuring Mission GMI GPM Microwave Imager VIS Visible GOES Geostationary Operational Environmental Satellite VLab Virtual Laboratory for Education and Training in Satel-lite Meteorology GPCC Global Precipitation Climatology Centre WCRP World Climate Research Programme GPCP Global Precipitation Climatology Project WMO World Meteorological Organization GPM Global Precipitation Measurement mission WWRP World Weather Research Programme GPM-GV GPM-Ground Validation.