“21·7”河南特大暴雨的中尺度系统活动特征  

Active Characteristics of Mesoscale Systems during the Heavy Rainfall in Henan Province in July 2021

作　　者：张元春[1,2] 孙建华 傅慎明[3] 汪汇洁 付亚男[1,4] 汤欢 魏倩 ZHANG Yuanchun;SUN Jianhua;FU Shenming;WANG Huijie;FU Ya’nan;TANG Huan;WEI Qian(Laboratory of Cloud–Precipitation Physics and Severe Storms,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081;International Center for Climate and Environment Sciences,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;University of Chinese Academy of Sciences,Beijing 100049;China Meteorological Administration Training Center,Beijing 100081)

机构地区：[1]中国科学院大气物理研究所云降水物理与强风暴重点实验室,北京100029 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]中国科学院大气物理研究所国际气候与环境科学中心,北京100029 [4]中国科学院大学,北京100049 [5]中国气象局气象干部培训学院,北京100081

出　　处：《大气科学》2023年第4期1196-1216,共21页Chinese Journal of Atmospheric Sciences

基　　金：灾害天气国家重点实验室开放课题2021LASW-A10;国家自然科学基金项目41975057、41975056。

摘　　要：2021年7月17日至22日河南省遭遇了罕见特大暴雨过程,特别是郑州市在7月20日出现了极端降水事件。本文首先分析了有利的大尺度环流背景,然后采用多源高分辨率观测和再分析资料深入分析了此次特大暴雨过程中不同阶段的水汽来源以及中尺度系统的活动特征。此次特大暴雨过程主要分为三个阶段,其主要的中尺度系统包括:黄淮气旋、中尺度对流系统(MCS)以及与MCS伴随的中尺度对流涡旋(MCV)。第一阶段(7月17~18日)主要为分散性降雨,水汽主要来自于南海、东南沿海、西北太平洋、长江中游地区的近距离水汽输送和河套地区。影响河南地区的中尺度系统为黄淮气旋,其于7月15日11时(协调世界时,下同)生成河南的东北部,18日23时在河南西南部消亡,垂直伸展最大高度为1000~350 hPa,维持时间约为89小时。第二阶段(7月19~20日),随着西太平洋副热带高压的北抬和台风“烟花”的西进北移发展,西北太平洋的水汽贡献也逐渐增多。由于黄淮气旋中心移动到河南西南部,其北部东南气流影响河南大部分地区。二级地形(伏牛山)东部的局地对流发展为MCS。由于地形的抬升作用,对流系统中强上升运动的维持有利于低层气旋性切变的增强,从而诱发了对流层中低层(750~600 hPa)MCV的生成。MCV的增强发展又进一步促进了MCS的维持以及偏南气流的增强。偏南气流输送大量水汽有利于午后分散性强对流单体的生成,分散对流单体与原有河南中北部MCS的合并后增强发展,从而造成了郑州极端小时降雨的出现。第三阶段(7月21~22日),暴雨过程的水汽主要来自于西北太平洋地区,其主要影响系统是MCS。低层气流受到二级地形(太行山)的阻挡,地形东部边界强的水汽通量辐合有利于MCS不断与新生对流单体合并发展,从而在河南、河北交界区域产生较强的降雨中心。Henan Province suffered severe torrential rainfall from 17 to 22 July 2021,which caused significant flooding and damage,specifically in Zhengzhou City.The water vapor sources and mesoscale systems were analyzed using highresolution observations and reanalyzed data,given that the stable synoptic circulations favored heavy rainfall.The main mesoscale systems considered included a Huang–Huai cyclone(HHC),four mesoscale convective systems(MCSs),and their associated mesoscale convective vortices(MCV).During the first period of heavy rainfall(17–18 July),the water vapor originated primarily from the South China Sea,the southeastern coastlines,the Northwest Pacific,the middle reaches of the Yangtze River,and the Hetao area.The main mesoscale system causing dispersed precipitation was HHC,which formed at 1100 UTC 15 July over the northeastern areas of Henan Province and dissipated at 2300 UTC 18 July.HHC extended from 1000 hPa to 350 hPa vertically and was maintained for 89 hours.With the Western Pacific subtropical high extending northwards and typhoon In-fa being in its second heavy rainfall period(19–20 July),more water vapor was generated from the Northwestern Pacific.The southwestern airflow of the northeastern part of HHC converged over the eastern edge of the second step terrain,and local convective cells developed into MCSs.The strong upward motion of MCSs promoted cyclonic wind convergence and triggered the formation of MCV at middle to lower levels of the troposphere(750–600 hPa).The intensified MCV further favored the maintenance of MCSs and enhanced the southerly flow.The dispersed convective cells moved northward along the southerly winds and merged with the original MCS over the middle and northern areas of Henan.The enhanced MCS resulted in extreme hourly rates of precipitation(201.9 mm h^(−1))at Zhengzhou.The precipitation was mainly over the boundary of Henan and Hebei provinces for the third period of heavy rainfall because the maintenance of MCSs was being continuously combined with newborn c

关 键 词：特大暴雨 中尺度对流涡旋 黄淮气旋 中尺度对流系统 

分 类 号：P445[天文地球—大气科学及气象学]