2022年7-8月黄河中游强降水极端性特征及其形成机制  

Extreme Characteristics and Formation Mechanism of Heavy Rainfall in the Middle Reaches of the Yellow River from July to August 2022

作　　者：乔春贵[1,2,3] 王国安 QIAO Chungui;WANG Guoan(Henan Key Laboratory of Agrometeorological Support and Applied Technique,China Meteorological Administration,Zhengzhou 450003,Henan,China;Yellow River Basin Meteorological Center,Zhengzhou 450003,Henan,China;Henan Meteorological Observatory,Zhengzhou 450003,Henan,China;Henan Meteorological Observation Data Center,Zhengzhou 450003,Henan,China)

机构地区：[1]中国气象局河南省农业气象保障与应用技术重点开放实验室,河南郑州450003 [2]黄河流域气象中心,河南郑州450003 [3]河南省气象台,河南郑州450003 [4]河南省气象探测数据中心,河南郑州450003

出　　处：《高原气象》2024年第4期919-932,共14页Plateau Meteorology

基　　金：河南省联合基金(应用攻关类)项目(222103810092);中国气象局气象能力提升联合研究专项(22NLTSY005);河南省科技厅科技攻关项目(212102310025,232102320027);预报员联盟复盘总结专项(FPZJ2023-077)。

摘　　要：采用国家和省级气象站降水观测资料、欧洲中期天气预报中心ERA5再分析资料和美国国家环境信息中心地形高程数据等,详细分析了2022年7-8月黄河中游持续强降水过程的极端性特征和形成机制。结果表明:(1)研究时段黄河中游共出现11轮强降水过程,具有持续时间长、累计雨量大、降水时间间隔短、强降水落区重叠性高等特点;18个站点累计降水量的标准化距平超过2.5,多次降水过程中最大雨强超过50 mm·h^(-1),表现出显著极端性特征,且8月降水的极端性强于7月;强降水雨带分布和黄河中游地形特征密切相关。(2)7-8月亚洲中高纬度贝湖附近高度场标准化距平达-2.5~-1.5(8月超过-3.5),低槽较常年同期异常偏强;强降水过程中副高西脊点呈西进状态,7月副高脊线和北界南北摆幅较大,副高的每一次南北摆动与来自贝湖的冷空气结合,引发一次次强降水过程;8月副高脊线和北界缓慢南退,摆幅较小,持续性强降水形成于副高边缘。(3)8月水汽输送来自孟加拉湾、南海和东海,整层水汽通量积分标准化距平达2.5以上,PWAT维持40~60 mm,其标准化距平在内蒙古南部和晋陕区间北部均为2.5~3.5,局部3.5以上,水汽条件明显强于7月。(4)黄河中游上空存在上干冷下暖湿的不稳定层结,中低层36°N以北形成锋生,北部整层出现上升运动,垂直速度标准化距平达-2.5~-0.5,异常偏强,与强降水落区对应。(5)8月锋生函数分析表明,黄河中游北部降水发生前及发生时均有锋生,锋生值增减与降水强弱变化趋势一致;变形项对总锋生贡献大,倾斜项对总锋消贡献大;降水强度大的过程,锋生伸展高度较高,强度小的过程锋生高度较低,锋生值相对较小。The extreme characteristics and formation mechanism of the sustained heavy rainfall process in the middle reaches of the Yellow River from July to August 2022 were analyzed in detail using precipitation observation data from national and provincial meteorological stations,ERA5 reanalysis data from the European Medium Range Weather Forecast Center,and terrain elevation data from the National Environmental Information Center of the United States.The results indicate that:(1)a total of 11 heavy precipitation processes occurred in the middle reaches of the Yellow River during the research period,characterized by long duration,large cumulative rainfall,short precipitation time intervals,and high overlap of heavy rainfall areas.The standardized anomaly of accumulated precipitation at 18 stations exceeds 2.5,the maximum hourly rainfall intensity exceeds 50 mm/h during multiple processes,exhibiting significant extreme characteristics,and the extreme of precipitation is stronger in August than that in July.The distribution of heavy rain bands is closely related to the topographic characteristics of the middle reaches of the Yellow River.(2)From July to August,the standardized anomaly near Lake Baikal in mid to high latitudes Asia reached-2.5 to-1.5(Exceeding-3.5 in August),and the low trough is abnormally strong compared to the same period in previous year.During processes of heavy precipitation,the western ridge of the subtropical high is in a westward moving state.The ridge line of the subtropical high and the northsouth boundary of the northern boundary have a large swing in July.Each north-south oscillation of the subtropical high combines with cold air from Lake Baikal,triggering a series of heavy precipitation processes.The ridge line and northern boundary of the subtropical high slowly retreat to the south in August with a small amplitude,and persistent heavy precipitation occurred at the edge of the subtropical high.(3)The water vapor come from the Bay of Bengal,South China Sea,and East China Sea,with an integrate

关 键 词：黄河中游 极端降水 环流异常 副热带高压指数 锋生函数 

分 类 号：P458.11[天文地球—大气科学及气象学]