PERSIANN Dynamic IR–Rain-Rate Model (PDIR) for High-Resolution, Real-Time Satellite Precipitation Estimation

Measurements of precipitation at a high spatiotemporal resolution are an important input for hydrometeorological and water resources studies; decision making in disaster management; and weather, climate, and hydrological forecasting. Moreover, to monitor and manage catastrophic disasters such as flash floods, which occur within a few minutes of excessive rainfall, or complex drought phenomena that cause major socio-economic impacts, high-resolution real-time precipitation estimation of great precision is pivotal. A major limitation of satellite infrared (IR)-based algorithms is their reliance on cloud-top temperature (Tb) without incorporating information from underneath the clouds. This is especially noteworthy over the western US, where current IR-based precipitation products fail to accurately capture rainfall events. We propose an algorithm that utilizes climatological data to create a dynamic Tb-Rain rate (RR) relationship that better estimates precipitation, especially over the western US. PERSIANN-Dynamic Infrared-Rain rate (PDIR) system improves the PERSIANN framework by increasing the Tb segmentation threshold, modifying the prior watershed delineation segmentation technique, using Gaussian mixture method for cloud classification, increasing the number of cloud types by extracting in the monthly scale, training dynamic Tb-RR curves with high resolution Multi-Radar Multi-Sensor (MRMS) data and utilizing the SCE-UA optimization technique. PDIR datasets are validated over the western US across several temporal scales including annual, monthly, and daily. In addition, validation is performed for specific extreme atmospheric river (AR) events since ARs are of great importance to the western US, owing to their tendency to bring torrential rainfall. The results show that PDIR is significantly superior to other existing satellite precipitation products in detecting heavy rainfall. The results also provide further evidence that PDIR might be effective in storm monitoring, the design of early warning systems, and disaster management plans for heavy storms associated with ARs over the US west coast.