关键词: 暖季, 极端小时强降水, 阈值, 频次

Abstract:

Based on the hourly precipitation data of national and regional stations from 2013 to 2022, the frequency, intensity and extreme value of extreme hourly heavy precipitation in Henan province during the warm season were studied by taking the 99.5% percentile as the threshold. The results show that the threshold of extreme hourly heavy precipitation in Henan province during the warm season is mainly concentrated in the range of 30~50 mm, while the threshold above 50 mm is mainly located in the northern and the middle eastern parts of Henan province. The intensity of extreme hourly precipitation is large in the east and north Henan province while small in the west, and the high value areas are mainly located in the eastern Taihang Mountain and the plains in east central Henan province. The frequency is more in the west and less in the east. Compared with national stations, regional stations can better show the extreme, discrete and localized nature of extreme hourly precipitation. In terms of annual variation trend, the frequency increases, the intensity decreases, while the change of extreme value is not obvious. In terms of monthly variation, the frequency, intensity and extreme value exhibit a single-peak distribution. National and regional stations are similar in frequency with peaks in July, while different in intensity and extreme value with peaks of national stations in June and July, with peaks of regional stations in July and August respectively. Moreover, the intensity and extreme value of regional stations are larger than those of national stations. The diurnal variation of frequency, intensity and extreme value shows a typical bimodal structure, with one peak located from afternoon to evening and another one located from night to early morning respectively, which is most obviously in July and August.

Key words: Warm season, Extreme hourly precipitation, Threshold, Frequency