Enhancing summer extreme precipitation prediction in the Yangtze River Basin through CWRF downscaling and its skillful multi-physics ensemble approach.

This study employs the regional Climate-Weather Research and Forecasting model (CWRF) downscaling and its skillful multi-physics ensemble approach to enhance summer extreme precipitation prediction in the Yangtze River Basin. The CWRF simulations at 30-km driven by the ECMWF Interim reanalysis during 1980–2015 are conducted using 28 model physics configurations. The prediction skill is evaluated for four standard indices: simple daily intensity, total extreme precipitation and its fraction to total precipitation, and maximum consecutive dry days. The control CWRF configuration outperforms the driving reanalysis, which underestimates all indices despite its utilization of surface data assimilation. Notably, the downscaling skills of CWRF exhibit substantial variability across diverse physics configurations, with cumulus parameterization being most influential. In particular, the ensemble cumulus parameterization (ECP) demonstrates remarkable proficiency in capturing both spatial patterns and interannual variations. This proficiency is further magnified through ECP’s integration with Morrison or Morrison-aerosol microphysics and CCCMA, CAML or CAM radiation schemes, significantly enhancing overall skills. The ensemble average of these skill-enhanced physics configurations better reproduces observed geographic distributions and interannual anomalies for all four indices, surpassing the control CWRF’s performance. This improvement can be primarily attributed to a more accurate portrayal of the East Asian Jet and its associated regional circulation patterns by the ensemble. These findings underscore a significant opportunity for enhancing predictions of extreme precipitation by further refining the physics representation within the climate system coupling, especially among cumulus, microphysics, and radiation processes. Optimizing the multi-physics ensemble approach holds substantial promise in this endeavor. [ABSTRACT FROM AUTHOR]