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气象:2018,44(6):790-801
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冷涡对两类对流系统结构演变作用的个例模拟对比分析
蔡雪薇,谌芸,沈新勇,刘靓珂,葛蕾
(南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,南京 210044; 国家气象中心,北京 100081; 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)
Comparative Simulation Analysis of the Effect of Cold Vortex on Structural Evolution of Two Types of Mesoscale Convective Systems
CAI Xuewei,CHEN Yun,SHEN Xinyong,LIU Liangke,GE Lei
(Key Laboratory of Meteorological Disaster, Ministry of Education / Joint International Research Laboratory of Climate and Environment Change / Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044; National Meteorological Centre, Beijing 100081; Key Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)
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投稿时间:2017-11-02    修订日期:2018-04-27
中文摘要: 2015年8月22日,在同一冷涡背景下,华北东北部形成了多单体风暴,而在黄淮地区出现飑线过程。本文根据观测资料给出冷涡对中尺度对流系统发生发展的动力和热力作用,并基于WRF中尺度数值模式的模拟结果,对比分析了两类对流系统的形态结构演变和运动过程的差异、差异产生的原因及冷涡的作用,主要结论如下:(1)两类对流系统均位于冷涡后部,但形态演变和运动过程差异显著,北部分散性对流受地面风辐合及地形抬升的共同影响发展形成多单体风暴,呈西北—东南排列,主要以前向传播的方式缓慢向东南偏南方向运动,带来短时强降水为主的天气;南部线状对流由山东西北部和河南北部形成的多个孤立单体合并后形成,随后在黄淮地区发展为飑线系统,在平流移动为主的作用下向东南方向快速运动,产生雷暴大风和冰雹天气。(2)北部多单体风暴在冷暖气团交界面形成,位于冷涡西南象限,低层水汽和能量充足;新对流单体在边界层被触发后,沿着低层切变线向高能区传播。(3)南部飑线系统在冷槽后的地面干暖区低压带中形成,中尺度对流系统产生的冷池和雷暴高压的出流与环境相互作用,低层水汽条件转好,使得单体不断传播和合并,发展为飑线系统。(4)中层后部入流的强度和环境水汽条件对两类对流系统组织化过程有不同影响,飑线中层后部入流的增强主要来自环境西风分量的增加,与冷涡发展演变使得环境风场增强有关;北部对流湿层深厚,所处的中层风场弱,不利于多单体风暴组织化发展;南部飑线系统位于更强的环境西风引导气流中,后部中层入流强、高层环境空气干,有利于强下沉气流形成,从而促进雷暴高压和冷池的发展,强下沉气流还使中低层的风速增加,垂直风切变增强,有利于对流单体组织化发展形成线状对流。
Abstract:The multi-cell storm in northeast of Huabei Region and squall line in Huanghuai Region happened under the same circulation background of northeast cold vortex on 22 August 2015. Based on meteorological observation data, this paper first shows the dynamic and thermodynamic effects of large scale cold vortex on the development of mesoscale convective systems. Then, based on the results of WRF mesoscale numerical model simulation, the differences between shape structure evolution and movement process of the two convective systems are compared. The reasons for structural evolution differences and effect of cold vortex are analyzed as well. The research suggests that: (1) Both of the two convection systems are located behind the cold vortex, but their shape evolutions of the two mesoscale convective systems are different. The northern convection was impacted jointly by surface winds and uplift of terrain, forming a multi-cell storm with a northwest-southeast alignment. It traveled slowly south-southeast by downwind propagation, bringing short-time severe rainstorm. The southern linear convection was formed by combination of several isolated cells which formed in northwest of Shandong and north of Henan. Later, the linear convection developed in Huanghuai Region into a squall line system, which moved rapidly to southeast under the action of advection movement, resulting in thunderstorm and hail. (2) The northern multi-cell storm formed in the interface of cold and warm air masses, located in the southwestern quadrant of cold vortex with sufficient low-level water vapor and energy. After being triggered by the boundary layer, the new convective cell propagated along lower shear line to the high-energy zone. (3) The southern squall line system formed in low pressure belt of surface warm area behind cold trough. Cold pool and outflow of thunderstorm high pressure generated by mesoscale convective system interacted with the environment, causing cell to continue to spread, merge and develop into a squall line system. (4) The intensity of mid-level rear inflow and water vapor condition had significantly different effects on the organization of the two convective systems. The increase of rear inflow of squall line in middle layer mainly came from the increase of westerly component, which was related to enhancement of environmental wind field caused by evolution of cold vortex. The mid-layer wind field where the northern convection was located was weak and the whole layer was wet, which was not conducive to the development of multiple cell storm organizations. The middle troposphere of south squall line was located in westerly steering airflow which was stronger than the northern convection. The inflow was strong and ambient air was dry, favorable for the formation of strong descending airflow, enhancing the development of thunderstorm high pressure and cold pool. Strong downdraft increased wind speed in middle and lower layers and enhanced vertical wind shear, which is conducive to the development of convective cell organization and formation of linear convection.
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基金项目:国家重点研发计划(2017YFC1502501和2016YFC0203301)、国家自然科学基金面上项目(41175048、41530427和41375051)及国家重点基础研究发展计划(973计划)(2015CB453201)共同资助
引用文本:
蔡雪薇,谌芸,沈新勇,刘靓珂,葛蕾,2018.冷涡对两类对流系统结构演变作用的个例模拟对比分析[J].气象,44(6):790-801.
CAI Xuewei,CHEN Yun,SHEN Xinyong,LIU Liangke,GE Lei,2018.Comparative Simulation Analysis of the Effect of Cold Vortex on Structural Evolution of Two Types of Mesoscale Convective Systems[J].Meteor Mon,44(6):790-801.