Sampling Considerations for a Robust Precipitation Constellation

Precipitation, a key link to the water and energy cycles, arises in sub-cloud-scale patches over space and time. The existing GPM precipitation constellation offers excellent precipitation information by exploiting data captured with a diverse set of instruments. GPM promotes the goal of observations every 3h or less at least 90% of the time at all latitudes. We investigate the sampling properties of GPM constellation instruments and their impact on the accuracy of precipitation estimates. This study focuses on the Advanced Microwave Scanning Radiometer (AMSR), the Special Sensor Microwave Imager/Sounder (SSMIS), the Microwave Humidity Sounder (MHS), the Advanced Technology Microwave Sounder (ATMS), and the GPM Microwave Imager (GMI) and discusses their sampling interval. Our analysis is cast using the Multi-Radar Multi-Sensor system (MRMS) over a time period of 1 year over a case study region in the southern United States. To simulate the sampling error based on the MRMS-based climatology, we spatially and temporally collocate MRMS precipitation data with overpasses by each of the GPM constellation instruments. Sampling error formulated as a function of time scale from 1 hour to daily follow the simple scaling law with sampling errors following near normal distributions from SSMIS and MHS. This study contributes to evaluating recent configurations of the constellation, as well as possible additions and removals of satellites in future configurations.