2022年长江中下游夏季异常干旱高温事件之环流异常特征  

Circulation anomalies characteritics of the abnormal drought and high temperature event in the middle and lower reaches of the Yangtze River in summer of 2022

作　　者：郝立生 马宁[1] 何丽烨[1] HAO Lisheng;MA Ning;HE Liye(Tianjin Climate Center,Tianjin 300074,China)

机构地区：[1]天津市气候中心,天津300074

出　　处：《干旱气象》2022年第5期721-732,共12页Journal of Arid Meteorology

基　　金：中国气象局创新发展专项(CXFZ2021J30、CXFZ2022J017)资助。

摘　　要：2022年夏季长江流域发生了建国以来最为严重的干旱高温气候事件,对当地工农业生产、居民生活、生态安全等造成严重影响。为深入认识这次干旱高温气候事件发生的原因和改进气候预测技术,利用1951—2022年2400多测站气温、降水数据和NCEP/NCAR再分析数据等资料,采用T-N波作用通量、视热源Q_(1)(Q_(2))诊断和合成分析、距平分析等方法,从大气环流异常的角度进行综合分析。主要结论如下:(1)2022年夏季,500 hPa源自北大西洋地区的扰动异常偏强,在沿中高纬西风带向东传播时引发了明显的大槽大脊活动,波动能量主要沿西风带向东传播,没有出现在东亚向东南方向传播的特征,造成冷空气活动位置偏北,很难影响到长江流域。(2)2022年夏季,500 hPa高度场在青藏高原上空出现明显正距平扰动,尤其8月扰动进一步加强,东移到长江流域,诱发西北太平洋副热带高压西伸,使得副热带高压呈现东西带状分布。副热带高压(简称“副高”)西部完全控制了长江流域地区,一方面副高阻挡了北方冷空气南下,另一方面副高长时间维持下沉运动,不利于降水发生,有利于下沉增温。(3)2022年夏季,热带对流区(视热源)位置异常偏南到赤道以南(气候态在5°N—20°N),有两方面影响:一是造成哈德来经圈环流(Hadley Cell)上升支异常偏南,长江流域在8月为异常下沉区,不利于降水发生,有利于下沉增温效应的出现;另一方面造成2022年夏季亚洲热带夏季风偏弱、东亚副热带夏季风偏强,低频信号向长江中下游传播明显偏弱,这些都不利于长江中下游降水过程的发生。(4)高纬、中低纬、低纬热带地区环流异常协同作用造成2022年长江流域夏季出现异常的干旱高温气候事件。要预测长江流域夏季降水或高温干旱,需提前关注500 hPa北大西洋地区扰动信号的发生及未来传播特征,青藏高原上空高度场扰动的发�In order to deeply understand the causes of the abnormal drought and high temperature climate event in the Yangtze River Basin in summer 2022 and improve the climate prediction technology,this paper makes a comprehensive analysis from the perspective of atmospheric circulation anomaly by using temperature and precipitation data from more than 2400 observation stations and NCEP/NCAR reanalysis circulation data from 1951 to 2022,and using T-N wave activity flux,apparent heat source Q_(1)(Q_(2)) diagnosis and composite analysis,anomaly analysis and other methods.The main conclusions are as follows:(1) In summer of 2022,the disturbance originating from the North Atlantic region was unusually strong at 500 hPa,triggering an obvious large trough and ridge activity when it was propagating eastward along the mid-and high-latitude westerly belt.The wave energy mainly propagated eastward along the westerly belt,without the characteristic of propagating southeastward in East Asia,resulting in the northward location of cold air activity,which hardly affected the Yangtze River Basin.(2) In summer of 2022,the 500 hPa height field showed a significant positive anomaly disturbance over the Qinghai-Tibet Plateau region,which further strengthened in August and moved eastward to the Yangtze River Basin,inducing the westward extension of the Northwest Pacific subtropical high,making the subtropical high appear as an east-west zonal distribution.The western part of the subtropical high completely controlled the Yangtze River Basin area.On the one hand,the subtropical high blocked the cold air from the north to the south,on the other hand,the subtropical high maintained the sinking movement for a long time,which was not conducive to precipitation and conducive to sinking and warming.(3) In summer 2022,the location of the tropical convection area(apparent heat source) was abnormally south to the south of the equator(the climate state is between 5°N and 20°N),which has two impacts:one is to cause the ascending branch of the Hadley mer

关 键 词：高温干旱 环流异常 诊断分析 归因 长江流域 

分 类 号：P466[天文地球—大气科学及气象学]