摘要
基于2010-2019年辽宁东南部复杂地形区域的观测降水数据,筛选出44次暴雨事件(TRECT),结合合成分析方法及绕流、爬流方程提出对研究区域低层风场的分解方案,系统探究了该类事件的环流前兆、环流场的共性特征以及地形对区域性暴雨的动力影响机制。结果表明:(1)TRECT事件发生前6天,欧亚大陆对流层中层表现为中阻型阻塞高压,随后贝加尔湖浅槽东移发展,事件当天副热带高压北上加强,关键区西部上空形成斜槽,对流层低层出现闭合气旋性环流,地面华北低压发展东移,关键区位于倒槽顶部,为范围降水提供了有利的环流背景。(2)事件鼎盛期,爬、绕流在关键区地形主体呈现南强北弱的特征,大值区集中于长白山余脉的喇叭口地形区域,爬流强度达4 m·s^(-1)以上的区域位于喇叭口低地势山坡南侧,绕流则环绕于高地势山体周边,且爬流和绕流经向分支起主导作用。爬流和绕流分别以翻越和绕行山体的方式进入喇叭口,路径主要有来自黄海洋面和朝鲜境内的两支气流。(3)在喇叭口区域,爬流贡献的上升运动占整个系统上升运动的80%以上,是降水增幅的主要动力来源,绕流则在地形作用下形成局地正涡度,进一步增强了降水的动力条件。本研究揭示了长白山余脉复杂地形区域暴雨的前期大尺度环流系统演变特征,探究了该区域暴雨的前期环流前兆,并通过中尺度地形动力强迫作用,重点分析了辽宁省东南部喇叭口地形的抬升辐合效应、绕流涡度发展特征,为提升区域山地型暴雨预报准确率提供了理论依据。
Based on the observed precipitation data from 2010 to 2019 in the complex terrain region of southeastern Liaoning,this study identified 44 torrential rain events(TRECT).By employing composite analysis methods and decomposing the lower-level wind field using flow-over and flow-around equations,the circulation precursors,common characteristics of circulation fields,and the dynamic impact mechanism·s of topography on regional torrential rain were systematically investigated.The results indicate that:Six days prior to the occurrence of TRECT events,the mid-troposphere over the Eurasian continent exhibited a blocking high pattern,followed by the eastward movement and development of a shallow trough near Lake Baikal.On the day of the event,the subtropical high moved northward and intensified,forming a slanting trough over the western part of the key area,with a closed cyclonic circulation appearing in the lower troposphere.The North China low-pressure system developed and moved eastward,positioning the key area at the top of the inverted trough,providing a favorable circulation background for widespread precipitation.During the peak period of the event,the flow over and around the terrain in the key area showed stronger southern and weaker northern characteristics,with high-value areas concentrated in the trumpet-shaped terrain region of the Changbai Mountain's foothills.Areas with flowover speeds exceeding 4 m·s^(-1) were located on the southern slopes of the low-altitude hills in the trumpet-shaped area,while flow-around was observed around the high-altitude mountains,with meridional branches of both flows playing a dominant role.The flow-over and flow-around entered the trumpet-shaped area by crossing and bypassing the mountains,respectively,primarily from two air stream·s originating from the Yellow Sea and the Korean Peninsula.In the trumpet-shaped area,the upward motion contributed by the flow-over accounted for more than 80%of the total system's upward motion,serving as the main dynamic source for precipitation enhancement.The flow-around,under the influence of topography,formed local positive vorticity,further enhancing the dynamic conditions for precipitation.This study systematically investigates the evolutionary characteristics of precursor large-scale circulation system·s associated with torrential rain events in the complex topography of the Changbai Mountain foothills,exploring atmospheric circulation precursors preceding extreme precipitation.Through mesoscale topographic dynamic forcing mechanism·s,it specifically elucidates the orographic lifting-convergence effect and flow-around vorticity development within the trumpet-shaped terrain of southeastern Liaoning Province.It provides a theoretical basis for improving the accuracy of regional mountain type rainstorm forecast.
作者
刘成瀚
陆井龙
阎琦
王月
焦浩然
金妍
LIU Chenghan;LU Jinglong;YAN Qi;WANG Yue;JIAO Haoran;Jin Yan(China Meteorological Administration Hydro-Meteorology Key Laboratory,Beijing 100081,China;Liaoning Meteorological Observatory,Shenyang 110166,Liaoning,China;Institute of Atmosphere Environment,China Meteorological Administration,Shenyang 110166,Liaoning,China;Panjin National Climate Observatory,Panjin 124000,Liaoning,China;Shenyang District Meteorological Bureau,Shenyang 110166,Liaoning,China;Shanghai Meteorological Center,Shanghai 200030,China)
出处
《高原气象》
北大核心
2026年第1期148-163,共16页
Plateau Meteorology
基金
中国气象局水文气象重点开放实验室开放研究课题(24SWQXZ019)
中国气象局沈阳大气环境研究所联合开放基金课题(2024SYIAEKFZD03)
中国气象局创新发展专项(CXFZ2025J021,CXFZ2025J33)
辽宁省科技计划联合计划项目(2024-MSLH-243)
国家重点研发计划项目(2018YFC1507305)
辽宁省气象局科研项目(202302)。
关键词
复杂地形
暴雨
环流前兆
爬流
绕流
complex topographic
torrential rain
circulation precursors
flow over
flow around
