Advancing Precipitation Retrievals From Cross-Track Passive Microwave Sensors

The quantitative estimation of precipitation from satellite-based passive microwave sensors is now an essential element in global precipitation measurements. In particular, estimates derived from cross-track passive microwave sensors now form the majority of the observations, consequently improving and refining such techniques is critical to provide precipitation estimates at the spatial and temporal sampling necessary to adequately capture the natural variability of precipitation. This presentation outlines the Precipitation Retrieval and Profiling Scheme (PRPS), initially developed for use with the Sondeur Atmospherique du Profil d'Humidite Intertropicale par Radiometrie (SAPHIR) instrument, but has more recently been adapted for use with other cross-track sensors, including the Microwave Humidity Sounder (MHS) instruments. The technique exploits the non-sun-synchronous sampling of the Global Precipitation Measurement (GPM) mission sensors with that of SAPHIR and sun-synchronous sampling of other sensors to provide co-temporal and co-located observations to generate the a priori retrieval database. This database is then used by the retrieval to extract the surface precipitation and the precipitation profile that best matches the observed brightness temperatures. In addition, the PRPS technique provides truly independent satellite-based precipitation estimates, not being reliant upon dynamic ancillary data, such as those provided by models. Comparisons against surface reference data, comprised of gauge and radar, show that the performance of the technique is equal to that of other current precipitation retrieval techniques.