梅雨锋暴雨中尺度对流系统的组织特征和触发条件分析
投稿时间: 2016-12-29  最后修改时间: 2017-04-26  点此下载全文
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作者单位E-mail
赵宇 南京信息工程大学 zy0817@126.com 
裴昌春 南京信息工程大学  
杨成芳 山东省气象台  
中文摘要:利用常规气象观测、地面加密自动站和多普勒天气雷达资料,结合WRF (Weather Research and Forecast) 模式的模拟资料,对2015年6月26—28日长江中下游的一次梅雨锋暴雨过程中尺度对流系统MCS(Mesoscale Convective System)的组织特征和对流触发条件进行了分析。结果表明:(1)暴雨过程线状MCS的发展有多种组织方式,发展初期为东西向雨带不断的“后部建立”和随后对流单体的“列车效应”;发展成熟期,对流元向东北—西南向发展,形成多个近乎平行的东北—西南向短雨带,有2种尺度的对流组织方式:新生对流单体沿着单个雨带向东北方向的“列车效应”以及短雨带沿着线状MCS向东平流的“列车带效应”;发展后期,梅雨锋锋面雨带呈现东北—西南向短雨带不断东移的“列车带效应”。(2)低空急流的持续加强为对流的发生发展提供了条件性不稳定和对流有效位能,偏南暖湿气流在向东北推进过程中,在风速辐合处被强迫抬升至自由对流高度,释放不稳定能量,触发对流。(3)对流雨带内近地面向南的冷出流与低层西南暖湿气流的持续交汇和相互作用有利于新单体生成发展,使雨带维持。
中文关键词:梅雨锋  中尺度对流系统  组织特征  触发
 
Analysis of organization modes and initiation conditions of an heavy-rain-producing mesoscale convective system along a Mei-yu front
Abstract:A heavy rainfall event occurred over the Yangtze-Huai River Basin on 26—28 June 2015.The organization modes and initiation conditions of mesoscale convective systems (MCS) were analyzed by using routine observation, automatic weather station, Doppler radar and the simulated data from WRF(Weather Research and Forecast)model. The results are as follows: (1) Many types of organization modes were found in the development of the linear MCS. Constantly back building of the east-west oriented rainbands and subsequent echo training of convective cells were the main development modes of MCS in the initial stage. The convective elements developed to the SW-NE and formed several nearly parallel NE-SW oriented convective rainbands in the mature stage. Two scales of convective organization were found: one is northeastward “echo training” of new convective cells along individual rainbands, and the other is eastward “band training” of the NE-SW oriented rainbands along the linear MCS. The Mei-yu front rainbands existed several parallel NE-SW oriented short rainbands and the short rainbands moved eastward in the late stage. (2)The continuous enhancement of low-level jet provided conditional instability and convective available potential energy for the generation and development of convections. The southerly warm and moist air was lifted to the level of free convection, released the unstable energies and initiated convection at the wind speed convergence zone. The consistent interactions of the cold outflow of convective cells and southwest warm and moist air in the low level are favorable for the generation and development of new cells, which maintain the rainband.
keywords:meiyu-front  mesoscale convective system  organization characteristics  initiation  backbuilding
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