Convection-permitting regional climate simulations over coastal regions in China

This study investigates the regional characteristics and land/sea differences in precipitation and wind along the coast of China, utilizing the Weather Research and Forecasting (WRF) model for continuous 10-year (2009-2018) simulations at 4 km resolution. The results indicate that the WRF model, operating at convection-permitting resolution, can accurately simulate annual precipitation and rainfall frequency, but tends to underestimate the precipitation over the ocean while overestimate the frequency of drizzle rain. The study also reveals that, along the Chinese coastal region, the sub-daily scale precipitation events are most frequent in Eastern China (EC), and WRF tends to underestimate the frequency of events lasting longer than 3 h. The WRF simulations show relatively slight difference in maximum precipitation between land and sea areas. The smallest deviation from the observation of maximum hourly precipitation is over the sea, below 20%. Furthermore, observations show that the diurnal cycle of precipitation peaks at 16:00-17:00 local time over land, with most afternoon precipitation lasting approximately 1 to 6 h. The WRF model successfully captures the observed diurnal variation of precipitation over land and sea in different regions. However, the WRF simulations indicate shorter duration of afternoon precipitation, lasting less than 5 h and an earlier peak. In addition, WRF adequately reproduces the annual and seasonal mean windspeeds for each region, with a slight overestimation during summer. WRF also reasonably captures the frequency distribution of windspeed and wind direction and can identify the occurrence frequency of land-sea breeze in each sub-region. Overall, the study offers valuable insights into the regional characteristics of precipitation and wind along the coast of China and highlights the WRF model's effectiveness in accurately simulating these phenomena. Convection permitting model (CPM) performs well in simulating the climate characteristics and regional differences in the Chinese coastal areas.There are significant land-sea contrast in the amount, frequency and intensity of precipitation along the eastern coast in China.Water vapor flux convergence and vertical motion due to topographic effects in the model lead to overestimated precipitation over land.