Abstract:

Based on the hourly precipitation data and ERA5 high-resolution data from 323 surface meteorological stations in Hainan Island from 2012 to 2021, the temporal and spatial variations of regional short-duration extreme rainfall (SDER) in recent 10 years were analyzed statistically and the circulation background of SDER was discussed using the synthetic analysis method as well.The results show that there are about 422.3 times of SDER in Hainan Island per year, accounting for 8% of SDER.The seasonal and diurnal variations of SDER were significant, most of which occurred in the afternoon of April to October (14:00-19:00), and the SDER most occurred in August.In recent 10 years, there are at most 11 times of SDER at a station located in the northwest of Hainan Island.The diurnal variation of SDER appears unimodal and the peak appears at 17:00 with a frequency of 62.1 times per year.The mean intensity of SDER in the afternoon was higher, with an average of 67.8 mm·h^-1 and a peak value of 111.5 mm·h^-1.The spatial variation of SDER in the whole year and warm season appears in two high-incidence regions including the northwestern and eastern coastal areas of Hainan Island.The weather system in the warm season dominantly affects the SDER in Hainan Island.The monthly spatial variation differences of SDER in Hainan Island are closely related to land and sea breeze and topography.The triggering conditions are various for each month, and there is relatively more SDER from July to August.

Key words: Extreme short-time heavy precipitation (SDER), Circulation background, Land and sea breeze