Incorporating NASA space-borne precipitation products into National Mosaic QPE operational system for improved precipitation measurements

Currently the NSSL/OU National Mosaic Quantitative Precipitation Estimation (NMQ) system incorporates data from all WSR-88D radars and automated rain gauge networks in the conterminous US. Despite these recent advances, reliable ground-based precipitation measurements are difficult to obtain over all regions of the world, including many mountainous regions (e.g., Intermountain West of the US), due to the lack of adequate ground radar coverage from intervening terrain blockages. The limitations of rain gauges and weather radar systems highlight the attraction of space-based meteorological satellites to obtain seamless regional and global precipitation information from the vantage point of weather forecasting, modeling the hydrological cycle, and climate studies. Also, this study enables us to continuously incorporate the to-be-upgraded GPM (Global Precipitation Mission) to the future polarimetric NEXRAD-based NMQ system.

In this study, we demonstrate the integration of the Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) products (4-km precipitation quantity, types, and 250-meter vertical profile of reflectivity) into the NMQ ground-based rainfall estimation system to fill in gaps with existing NEXRAD radar coverage. The QPE correction procedure includes three major steps. First, precipitation types are classified to convective and stratiform precipitation based on TRMM product 2A23 precipitation type classifications information at horizontal surface level. Second, we use the physically-based VPR model to find a representative VPR from TRMM VPRs and to adjust it from Ku-band to S-band. Third, we simulate the ‘apparent' VPR from ‘true' representative VPR and apply corrections. Results indicate improvements in precipitation estimation following the incorporation of space-based VPR information to data from ground radar networks.