从气候学角度理解“21.7”河南特大暴雨的形成机理  

Understanding the formation mechanism of the“21.7”extreme heavy rainfall event in Henan,China from a climatic perspective

作　　者：张智煜 黄安宁[1,2] 黄丹青 赵大军[3] 张艳[4] 顾春雷[1] 陈爽 ZHANG Zhiyu;HUANG Anning;HUANG Danqing;ZHAO Dajun;ZHANG Yan;GU Chunlei;CHEN Shuang(School of Atmospheric Sciences,Nanjing University,Nanjing 210023,China;Qinghai Lake Comprehensive Observation Research Station,Chinese Academy of Sciences,Gangcha 812300,China;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China;National Satellite Meteorological Center,Beijing 100081,China)

机构地区：[1]南京大学大气科学学院,江苏南京210023 [2]中国科学院青海湖综合观测研究站,青海刚察812300 [3]中国气象科学研究院灾害天气国家重点实验室,北京100081 [4]国家卫星气象中心,北京100081

出　　处：《大气科学学报》2024年第5期681-700,共20页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金项目(U2342207,42075020);灾害性天气国家重点实验室开放资助项目(2021LASW-A12);南京大学关键地球物质循环前沿科学中心研究基金中央高校基本科研业务费(020914380103,020914380104);江苏省气候变化协同创新中心资助项目。

摘　　要：2021年7月19—22日,河南省遭遇历史罕见特大暴雨,破纪录降水引发了严重的洪涝灾害。目前,“21.7”河南特大暴雨的研究大多针对降水个例,引发极端降水的气候学机制仍不明确。本文基于谱聚类方法,利用中国气象局多年历史站点降水资料和NCEP/NCAR再分析数据研究了1960—2021年华北地区夏季区域性极端降水事件的主控环流天气型,系统揭示了“21.7”河南特大暴雨的发生过程。结果表明,“21.7”河南特大暴雨发生在罕见天气型下,即西太平洋上空增强的远距离台风配合异常偏西北的西太平洋副热带高压与异常偏东北的南亚高压。该天气型虽然仅贡献了华北地区夏季区域性极端降水事件的5.97%,却易导致更强的极端降水事件。台风和副高之间的盛行东南风将水汽从西太平洋输送到河南,对流层高低层强烈的风切变引发的垂直上升运动导致了“21.7”河南暴雨的发生。河南及周边地区对流层低层更加强烈的上升运动与非绝热加热之间的正反馈效应使得“21.7”河南暴雨相对同一天气型下的其他特大暴雨事件的极端性更强。本研究为理解和准确预测类似“21.7”河南暴雨的破纪录区域性极端降水提供了全新的气候学视角。An extraordinary extreme heavy rainfall event during 19—22 July 2021(“21.7”EHRE)attacked Henan Province of North China Plain(NCP)and led to tremendous catastrophes due to the record-breaking rainfall.Previous studies mainly focus on the individual case study of the“21.7”EHRE,which cannot give a general view of circulation characteristic from the climatic perspective,particularly for the extraordinary precipitation extremes with a rare occurrence.Based on 12-hourly observed precipitation data from rain gauge stations during 1960—2021 from CMA(China Meteorological Administration)and NCEP/NCAR reanalysis data,this study investigated the typical synoptic patterns responsible for the summer regional extreme precipitation events(REPEs)over NCP during 1960—2021 via the spectral clustering method and systematically revealed how the“21.7”EHRE occurred.Results show that the“21.7”EHRE occurred under a rare synoptic pattern featured by a distant typhoon over western Pacific accompanied by the farther northwestward extended western Pacific subtropic high(WPSH)and northeastward extended South Asia high(SAH).This synoptic pattern only contributes 5.97%of the total summer REPE occurrences over NCP but can lead to much stronger precipitation extremes.The water vapor transported by the strong southeasterly winds between the Typhoon In-Fa and WPSH from the western Pacific to Henan,and the intense ascending motion caused by wind shear between lower and upper troposphere over Henan Province led to the occurrence of the“21.7”EHRE.In addition,diagnosis analysis based on quasi-geostrophic omega equation indicates that the positive feedback on intense ascending motion and diabatic heating at lower troposphere over Henan province and surrounding areas distinguishes the“21.7”EHRE from the others under the same synoptic pattern.This study investigates the dominant large-scale synoptic pattern of the“21.7”EHRE in Henan to figure out the formation mechanism of the rarest REPEs in a climatic aspect.Findings of

关 键 词：“21.7”河南特大暴雨 区域性极端降水事件 天气分型 谱聚类 

分 类 号：P458.121.1[天文地球—大气科学及气象学]