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甘肃2024年“7·22”特大暴雨事件的降水极端性分析

Analysis on the precipitation extremes of extremely heavy rainstorm event in Gansu Province of the '7·22' in 2024

  • 摘要: 2024年7月22日—24日甘肃省河东地区出现了1961年以来最强区域性特大暴雨过程,此次过程具有累积降水量大、暴雨及以上量级降水落区集中、持续时间长、对流性降水强等特征。特大暴雨中心分别位于崇信县新窑林场站和通渭县陇阳车岔站,最大累积降水量为367.7 mm。利用国家和区域气象观测站的降水资料及地面-雷达-卫星三源融合降水分析产品,从降水强度、持续时间、历史极端性及强降水中心的时空演变等角度分析此次过程的极端性特征。结果表明:(1) 此次过程具有明显的对流性,降水效率高、持续时间长且雨强大,共456站出现短时强降水,其最长持续时间高达5 h,对总降水贡献率≥50%,特大暴雨区域代表站3 h内逐分钟累积降水量约占过程累积降水量的59.02%,逐分钟和逐小时最大雨强分别为8.9 mm·min−1和79.1 mm·h−1。两个特大暴雨中心强降水分别开始新窑林场站西北部和陇阳车岔站南部,在东-西-南-北方向摆动,结束于新窑林场站东北部和陇阳车岔站东南部。(2) 此次过程有265站过程降水量、93站短时强降水、91站短时强降水持续时间超过7月历史极值,其中成县、崇信、静宁、通渭4站最大日降水量分别为182.9、232、125.2和134.6 mm,均超过了建站以来最大值,约为历年7月平均降水量的1.4倍。此外,最大日降水量、过程累积降水量、区域平均暴雨量、日降水量破记录站数、短时强降水持续时间、最大1 h降水量、综合强度指数等指标均超过1961年以来其他区域性暴雨过程的最大值。

     

    Abstract: The Hedong region of Gansu Province experienced the most severe regional torrential rain event From July 22 to 24, 2024, since 1961. This event was characterized by high cumulative precipitation, concentrated areas of heavy rainfall, prolonged duration, and intense convective precipitation. The epicenters of the torrential rain were located at the Xinyao Forest station in Chongxin County and the Longyang Checha station in Tongwei County, with a maximum cumulative precipitation of 367.7 mm. Using 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, and intense rainfall. 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 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. The heavy rainfall at the two epicenters began in the northwest of Xinyao Forest station and the south of Longyang Checha station, oscillating in the east-west-south-north directions, and ended in the northeast of Xinyao Forest station and the southeast of Longyang Checha station. (2) 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.

     

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