Climatic distribution characteristics of hourly extreme precipitation over different terrain areas in Anhui Province

The spatial and temporal distribution characteristics of hourly extreme precipitation in Anhui Province are analyzed, based on the data of hourly precipitation at national stations of Anhui Province from 1979 to 2015. The results show that: ① The extreme precipitation threshold in Anhui Province demonstrates a tripolar distribution pattern of ‘+ - +’ from Northeast to Southwest. The occurrence probability of extreme precipitation is low in the northern area of Huaibei but its intensity is strong. The frequency and amount of extreme precipitation are strong in the west of the south of the Yangtze River and Dabie Mountain area. ② The annual average frequency of extreme precipitation in Anhui Province is 4.25 times/a, and the average amount of extreme precipitation in a single station is 127 mm/a. The frequency, amount and ratio of extreme precipitations have an obvious upward trend. ③ The stations in Anhui Province are divided into mountainous regions, transitional regions to North of mountainous regions, and plain and hilly regions. The frequency of extreme precipitations in the mountainous areas is the highest, and the frequency in the plain and hilly areas is the lowest. But the amount of hourly extreme precipitation is the highest and the daily variation is the strongest in the plain and hilly areas. ④ Most of the extreme precipitations in Anhui Province occur from afternoon to night, the frequency concentration of extreme precipitations in the transitional zone is the highest, and the daily variation is the most significant. The periods with fewer extreme precipitations are quite different in different terrain areas, and the period of extreme precipitations abating in a single day gradually moves backward from South to North.