Characteristics of Minute-and Hourly-Rate Rainfall of the"21·7"Extreme Precipitation Event in Henan
ZHANG Yani
LIU Xinhua
LAN Yu
ZHANG Xiaowen
ZHENG Yongguang
HUA Shan
Abstract：Using minute-and hourly-rate rainfall data from national and regional automatic stations across China during the summers of 2018-2024,this study analyzes the characteristics of minute-rate and hourly-rate rainfall in the"21·7"Henan extreme precipitation event,with a focus on the extremity of Zhengzhou's extreme hourly rainfall.The results show that hourly rainfall over 80 mm was predominantly observed in central and northern Henan,while lower amounts occurred west of Zhengzhou on 19 July and in southwestern Hebei on 21 July.Five-minute rainfall over 14 mm was also concentrated in central and northern Henan.The frequency distribution of five-minute rainfall reveals that the mode increases with the magnitude of hourly rainfall,indicating a general trend of intensified five-minute rainfall as hourly rainfall increases.However,for strong five-minute rainfall exceeding 20 mm,there is no trend of increasing intensity with higher hourly rainfall;instead,the increase is reflected in a higher frequency of such five-minute rainfall events within an hour.A statistical analysis of heavy hourly rainfall events(hourly rainfall exceeding 50 mm)across China over seven summers shows that the five-minute and one-minute rainfall intensities during Zhengzhou's extreme hourly rainfall were abnormal but not extremely so.In contrast,the cumulative duration of strong minute-scale precipitation within the hour reached extreme abnormality,suggesting that Zhengzhou's extreme hourly rainfall resulted primarily from the prolonged occurrence of strong minute-scale precipitation,with minute-scale rainfall intensity playing a secondary role.Radar echo dynamics reveal that a northeast-moving multicellular storm stagnated after moving northward over Zhengzhou,then turned and moved slowly southeastward,intensifying into an arc-shaped structure after the turn.The combined effects of storm intensification,direction change,and slow movement led to prolonged strong minute-scale rainfall.Thus,the prolonged effect of strong minute-scale precipitation may be related to the stagnation,turning,and intensification of multicellular convective storms as they moved northward over Zhengzhou.
Keywords：minute-rate rainfallhourly-rate rainfallextreme hourly rainfallheavy hourly rainfall eventstrong minute-scale precipitation event
Publication Date：2025-06-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 359-372 )