Convection-Permitting Simulations of Hourly Precipitation in the Yangtze River Delta Region: Evaluation and Future Projections

Short-duration heavy precipitation poses a persistent and significant risk to the densely populated Yangtze River Delta (YZR) region. This study employs the Weather Research and Forecasting (WRF) model at a convection-permitting scale (∼4 km) to simulate and project hourly precipitation over the YZR. We conducted a 10-year historical simulation (1998-2007) and three pseudo-global warming (PGW) experiments for the late 21^st century (2070-2099) under RCP2.6, RCP4.5, and RCP8.5 scenarios. The convection-permitting regional climate model (CPM) demonstrates robust skill in reproducing key characteristics of observed hourly precipitation including its diurnal cycle, event duration, peak intensity, and extremes. Future projections indicate hourly precipitation intensity is projected to increase, alongside a rising frequency of heavy precipitation events. Notably, short-duration events are expected to become more intense and frequent, while small-coverage heavy precipitation events are also projected to increase, thereby heightening regional climate risks. These findings underscore the critical value of CPMs for high-resolution climate risk assessment and the development of targeted adaptation strategies in the YRD.