东南风低空急流影响“21·7”郑州市极端暴雨分析  

Analysis of the impact of southeast wind low altitude jet on the “21·7” extreme heavy rain in Zhengzhou City

作　　者：张端禹[1] 崔春光[1] 王晓芳[1] 唐永兰[1] 李山山 ZHANG Duanyu;CUI Chunguang;WANG Xiaofang;TANG Yonglan;LI Shanshan(Key Laboratory of Basin Heavy Rainfall China Meteorological Administration/Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research,Institute of Heauy Rain,China Meteorological Administration,Wuhan 430205,China)

机构地区：[1]中国气象局武汉暴雨研究所中国气象局流域强降水重点开放实验室/暴雨监测预警湖北省重点实验室,武汉430205

出　　处：《气象科学》2024年第3期498-511,共14页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(42230612,41975058,42105012);湖北省气象局科技发展基金重点项目(2022Z02);湖北省自然科学基金资助项目(2023AFD091);中国气象局武汉暴雨研究所基本科研业务费专项(202402)。

摘　　要：利用中国气象局上海台风研究所热带气旋(Tropical Cyclone,TC)最佳路径数据、美国环境预报中心(National Center of Environmental Prediction,NCEP)最终分析格点资料(Final Analysis,FNL)及常规观测数据等,分析了2021年7月郑州极端暴雨过程的特征机理。结果表明:(1)两个TC同时远距离输送大量水汽,东南风低空急流与强降水关系密切。当东南风急流北上到太原、邢台等站后郑州市暴雨减弱。郑州市6 h降水超过62.5 mm站点数目增减与850 hPa地转偏差数值变化趋势一致。(2) 20日白天郑州站极端降水发生前,从850 hPa经500 hPa至200 hPa风向从东南风顺转为西南风。200 hPa与850 hPa水平风的垂直切变(Vertical Wind Shear,VWS)从最大值开始减小、可降水量(Precipitable Water Vapor,PWV)明显加大、不稳定程度减小,这些都是极端暴雨发生的有利条件。极端暴雨具有明显的湿对流特点。(3)纬、经向风变率诊断表明,最有利于郑州市850 hPa东风维持的因子是地转偏差,最有利于南风加大的因子是动量平流。动量对流促使郑州市暴雨过程850 hPa南风减小,故动量上、下传递并非850 hPa南风加大原因。Based on the best path data of Tropical Cyclone(TC) from the Shanghai Typhoon Research Institute of the China Meteorological Administration,Final Analysis(FNL) data from the National Center of Environmental Prediction(NCEP) and the conventional observation data,the characteristic mechanism of the extreme heavy rain process in Zhengzhou in July 2021 was analyzed.Results show that:(1) two TCs simultaneously transport a large amount of water vapor over a long distance,and the relationship between the southeast low-level jet and heavy precipitation is closely related.When the southeast wind rushes northward to stations such as Taiyuan and Xingtai,the heavy rain in Zhengzhou City weakens.The variation of the number of stations with precipitation exceeding 62.5 mm in 6 hours in Zhengzhou City is consistent with the variation trend of geostrophic deviation values at 850 hPa.(2) Before the occurrence of extreme precipitation at Zhengzhou station on 20 July,the wind direction changed from southeast to southwest from 850 hPa to 500 hPa and then to 200 hPa.The Vertical Wind Shear(VWS) of horizontal winds at 200 hPa and 850 hPa decreases from its maximum value,the Precipitable Water Vapor(PWV) increases significantly,and the degree of instability decreases,which are favorable conditions for the occurrence of extreme heavy rain.Extreme rainstorm was produced by moisture convection.(3) The diagnosis of latitude and longitude wind variability indicates that the most favorable factor for maintaining 850 hPa easterly winds in Zhengzhou City is geostrophic deviation.The most favorable factor for increasing southerly winds is momentum advection.Momentum convection promotes a decrease of southerly wind at 850 hPa during the heavy rain process in Zhengzhou,so the transfer of momentum up and down is not the reason for the southerly wind increase at 850 hPa.

关 键 词：极端暴雨 东南风低空急流 湿对流 地转偏差 南风动量平流 

分 类 号：P458.3[天文地球—大气科学及气象学]