Abstract:
The Hedong region of Gansu Province experienced the most severe regional torrential rain event From July 22 to 24, 2024, since 1961. This study utilizes precipitation data from national and regional meteorological observation stations, as well as ground-radar-satellite three-source fusion precipitation analysis products, the precipitation characteristics and extremity of this regional torrential rain event were analyzed from perspectives such as precipitation intensity, duration, historical extremity, and the spatiotemporal evolution of heavy precipitation centers. The results are as follows. (1) This event exhibited significant convective characteristics, with high precipitation efficiency, long duration, intense rainfall, large cumulative precipitation, and concentrated distribution of heavy rain and above. Two extreme rainstorm centers were identified, one at Xinyao Forest Farm station in Chongxin County and the other at Longyang Checha station in Tongwei County. The maximum cumulative precipitation reached 367.7 mm (Xinyao Forest Farm station). A total of 456 stations recorded short-duration heavy rainfall, with the longest duration reaching 5 hours, contributing to ≥50% of the total precipitation. The representative stations (LongyangChecha station and Xinyao Forest Farm station) in the torrential rain area showed that the cumulative precipitation over 3 hours accounted for approximately 59.02% of the total process precipitation, with maximum rainfall intensities of 8.9 mm·min
−1 and 79.1 mm·h
−1 per minute and per hour, respectively. (2) The heavy precipitation at the two extreme rainstorm centers began in the northwestern part of Xinyao Forest Farm station and the southern part of Longyang Checha station, respectively, and ended in the northeastern part of Xinyao Forest Farm station and the southeastern part of Longyang Checha station. (3) During this event, 265 stations recorded process rainfall, 93 stations recorded short-duration heavy rainfall, and 91 stations recorded short-duration heavy rainfall durations exceeding the historical July extremes. The maximum daily precipitation at Chengxian, Chongxin, Jingning, and Tongwei stations were 182.9 mm, 232 mm, 125.2 mm, and 134.6 mm, respectively, all surpassing the maximum values since the establishment of the stations, approximately 1.4 times the average July precipitation. Additionally, indicators such as maximum daily precipitation, cumulative process precipitation, regional average heavy rainfall, number of stations with daily rainfall breaking records, duration of short-duration heavy rainfall, maximum 1-hour precipitation, and comprehensive intensity index all exceeded the maximum values of other regional torrential rain events since 1961.