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闽西山区“7·22”极端降水过程中尺度对流特征 预览 被引量:1

Meso-scale Convective Characteristics of"7·22"Extreme Rain in the West Mountainous Area of Fujian
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摘要 2015年7月22日福建西部山区经历了一次罕见的极端降水过程,6h降水量高达254.9mm,24h最大降水量达295.5mm。利用常规天气资料、自动气象站、卫星云图、风廓线雷达以及多普勒天气雷达资料,分析此次过程的中尺度对流系统的环境条件及结构演变特征。分析表明:低空季风槽北抬减弱后的切变和高空高压之间的南北向槽缓慢向东北移动是此次强降雨的主要影响系统,不稳定能量加大、抬升凝结高度和自由对流高度低、大气可降水量大及中等到弱的垂直风切变形成有利于中尺度对流系统发展的环境条件。中尺度对流系统在发展过程中结构发生改变,由线状对流伴随层云(TL/AS)的结构转变为静止后向建立的中尺度对流系统,极端降水出现在静止后向传播阶段。高空冷空气入侵,低空西南急流加强并伴风速辐合,冷暖空气交汇导致中尺度对流系统加强发展,边界层西南气流在有利的喇叭口地形作用下加强抬升,北上受到山脉阻挡形成小涡旋,西北侧对流单体移入后不断加强,对流单体的移动方向和传播方向相反,中尺度对流系统形成静止后向传播,产生列车效应,出现极端降水。 An extreme severe rain occurred in the west mountainous area of Fujian on22July2015,with the precipitation of254.9mm for6hours and the maximum total precipitation of295.5mm.Using conventional observations,automatic weather station data,satellite data,wind-profiling radar and CINRAD-SA Doppler radar data,this extreme severe precipitation is analyzed focusing on the environmental conditions and structure characteristics of the meso-scale convective system(MCS).Results show that predominate influencing systems are the low-level shear line and the upper trough between subtropical high and the anticyclone over Yunnan and Guangxi.The reinforcement of unsteady convective stratification,decrease in the level of Iifting condensation and free convection,high atmospheric precipitable water and weak vertical wind shear over the rainstorm-hit area are all favorable to the development of MCS.The initial convective cloud develops on the edge of Guangdong and Fujian.Convective cells develop strongly with the favorable meso-scale environmental conditions.At the stage of northeast development,convective ceils are born in the north of MCS and move southeast.Many northwest and southeast short echo bands come into being one after another.MCS moves northeastward under actions of cell advection and storm propagation.At the stage of quasi-stationary,the strong temperature gradient area locates in the middle of MCS.The north and south cloud clusters weaken rapidly.The structure of MCS changes from training line and ad- joining stratiform MCS to back-building and quasi-stationary MCS in the stage of development.Backbuilding and quasi-stationary MCS results in the extreme severe rain.The northwest airflow on high level increases and extends to low level.The inflow in front of MCS on low level is strengthened and extends to high leveI.The cold air intrusion at high level and reinforcement of southwest jet with wind velocity convergence at low level over the rainstorm-hit area lead to the development of MCS.The effect of the trumpet-shaped t
作者 冯晋勤 刘铭 蔡菁 Feng Jinqin;Liu Ming;Cai Jing(Longyan Meteorological Office of Fujian Province,Longyan364000;Fujian Meteorological Observatory,Fuzhou350001)
出处 《应用气象学报》 CSCD 北大核心 2018年第6期748-758,共11页 Quarterly Journal of Applied Meteorology
基金 中国气象局预报员专项项目(CMAYBY2014-034) 中国气象局关键技术集成项目(CMAGJ2015M30).
关键词 极端降水 中尺度对流系统 静止后向传播 extreme severe rain MCS quasi-stationary back-propagating
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