Projection of Hourly Extreme Precipitation Using the WRF Model Over Eastern China

The Weather Research and Forecasting (WRF) model was applied to simulate the current and future climates over eastern China at a convection-permitting resolution (& SIM;4 km). A continuous 10-year (1998-2007) simulation was performed for the historical climate, and three pseudo-global warming (PGW) experiments driven by climate perturbations during 2070-2099 were conducted under the RCP2.6, RCP4.5, and RCP8.5 scenarios. After validation against reanalysis and observational data, the historical simulation was found capable of reasonably reproducing the characteristics of mean precipitation, extreme hourly precipitation, and large-scale circulation. The PGW experiments projected an increase in precipitation intensity over most regions, especially North China under the RCP8.5 scenario (up to 30%). However, the precipitation frequency was projected to decrease, especially over the Yangtze River Basin in summer. A wetting (drying) trend was observed over North China (South China) in summer (winter), due to the increase (decrease) in precipitation intensity (frequency). The intensity and frequency of extreme events were projected to increase over most areas of eastern China, and the increase was the most dramatic under the RCP8.5 scenario, indicating a greater flood risk under stronger global warming. The relationship between extreme precipitation and temperature (EP-T) displayed a hook-shape structure in both the present and future climates. The extreme precipitation intensity increased with temperature at a super Clausius-Clapeyron (C-C) scaling rate (> 7%/K) until reaching a peak at temperatures of around 25-29 & DEG;C, and then decreased at higher temperatures. The decreases were mainly attributed to moisture limitation at high temperatures. In the future, the EP-T relationship is expected to change mostly following the C-C law, with greater precipitation peaks under scenarios with higher carbon emissions, indicating that warmer climates contribute to further enhancement of extreme precipitation.