暴雨灾害 (Apr 2021)
Spatial and temporal distribution characteristics of hourly extreme rainfall in warm season in Henan
Abstract
Based on the hourly precipitation data from 2010 to 2018 at the 371 meteorological stations including the 122 national Automatic Weather Stations (AWSs) and the 249 backbone regional AWSs in Henan, we have conducted a statistical analysis of spatial and temporal distribution characteristics of hourly extreme rainfall in warm season (May to September) in Henan. The main results are as follows. (1) There are obvious differences in the threshold, intensity, frequency and contribution rate of hourly extreme rainfall in the 99.9th percentile in warm season in Henan. Their high value areas are mainly in the south of the Funiu Mountains, the east of the Huanghuai Plain and the southwest of the Hwai River basin. (2) Hourly extreme rainfall events occur mainly between July and August, of which the most is in July, and the regional extreme precipitation event is more than the quater of hourly extreme rainfall events. The diurnal variation of hourly extreme rainfall frequency in Henan is characterized by an obvious bimodal structure, in which the main peak value appears in the evening. The diurnal variation of the frequency of hourly extreme rainfall above 80 mm·h-1 shows a multi-peak structure, in which the main peak value is at night. (3) There are differences in the hourly extreme precipitation index for the four underlying surfaces including mountains, hill area, urban area and plain. The intensity of hourly extreme precipitation is the highest in the urban area, while its frequency is the lowest. The intensity of hourly extreme precipitation is the lowest in the mountains, while its frequency is the highest. (4) Although the diurnal variation of hourly extreme precipitation under all four types of underlying surfaces shows a bimodal pattern, there are obvious differences in some ways. The peak values of hourly extreme precipitation in the mountains occur mainly at night, followed by evening. Those in hilly area coexist at night and in the evening, and their intensities are comparable. Those in plain and urban occur mainly in the afternoon, and its peak intensity in the afternoon is higher in urban area.
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