袁美英,李泽椿,张小玲. 2010. 东北地区一次短时大暴雨β中尺度对流系统分析[J]. 气象学报, 68(1):125-136, doi:10.11676/qxxb2010.013
东北地区一次短时大暴雨β中尺度对流系统分析
Analysis of a meso scale convective system during a brief torrential rain event in Northeast China
投稿时间:2008-07-25  修订日期:2008-10-17
DOI:10.11676/qxxb2010.013
中文关键词:  短历时特大暴雨,MCC,β中尺度对流系统,辐合线,触发机制
英文关键词:Brief torrential rain, MCC, Meso-βconvective system, Shear convergence line, Trigger mechanism.
基金项目:国家自然科学基金(40505010)和黑龙江省科技厅项目(GC04C104-01)
作者单位
袁美英 黑龙江省气象台哈尔滨150030南京信息工程大学南京210044 
李泽椿 国家气象中心北京100081 
张小玲 国家气象中心北京100081 
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中文摘要:
      为了揭示东北短历时暴雨的观测事实和预报线索,利用自动站、卫星和常规气象观测资料相结合的方法,研究了2006年8月10日最大1 h雨量达到90.8mm(泰来,其中,后半小时占82 mm)的东北中西部百年一遇短历时特大暴雨中尺度对流系统(MCS)发展过程,及其发生的天气尺度背景和中尺度环境与触发机制。通过红外卫星云图和高分辨率的可见光云图,分析了MCS如何从一个γ中尺度发展为α中尺度对流复合体(MCC)的过程。分析表明,与6个市(县)半小时雨量超过33 mm相关联的MβCS分别发生在2个阶段,第1阶段在MCC形成之前,MβCS主要向东移动(最后合并成MCC),第2阶段,在MCC 成熟阶段,MβCS出现在MCC的西南边缘,而且最强短历时暴雨就发生在这里。在分辨率更高的可见光云图上发现,有北、西两条积云线,它们交汇的地方MβCS强烈发展并产生暴雨。分析MCS加强和产生暴雨的原因表明,首先,暴雨发生前夕暴雨区域具有高温、高湿和对流性不稳定层结,并存在明显的对流有效位能增加、抬升凝结高度及自由对流高度降低的现象,有利于暴雨发生。第二,β中尺度云团之间的合并,使MCS迅速增长,产生暴雨。第三,北、西两条积云线分别与地面风场中的两条辐合线相对应,在它们交汇处的较强辐合导致β中尺度云团强烈发展产生暴雨。分析MCS在MCC西南方向传播的原因表明,两条辐合线的移动方向和速度决定了暴雨MCS的传播方向。另外,偏北气流的出现和新老云团的新陈代谢过程是触发暴雨的关键因素。上述分析结果也为短历时暴雨的预报提供了有用的线索。
英文摘要:
      A brief torrential rain event with a broken-recorder 1h precipitation of 90.8 mm and especially 82 mm received at Tailai in the latter half hour reaching the level in a 100 year return period struck the middle-west of Northeast China on 10 August 2006.This paper is focused on synoptic background, mesoscale environment and triggering mechanism of the mesoscale convective systems (MCSs), by using the conventional and intensive observations from an automatic meteorological stations, satellite source and weather stations. The study of development process of MCS from meso-γto a meso-α convective complex (MCC) by analyzing IR cloud maps and high-resolution visible images ,shows that the MβCS associated to the total of six cities and towns each with >33 mm precipitation in 30 min (heavy rain MCS span divided into two stages, i.e., before and after MCC maturity) is characterized by the fact that at first stage, MβCS moves mainly towards the east, resulting in the mergence into a MCC, and at the second stage, MβCS occurs at the southwestern periphery of the MCC, where the brief strongest rainstorm happens. As shown on the still higher-resolution visible image there are two lines of cumuli and at their meeting location MβCS experiences so vigorous development that torrential rains take place. Study of the causes of MCS intensification and rainstorm shows that( 1) just before the heavy rains occur, there are high temperature, considerably wetness and unsteady convective stratification in the air over the rainstorm-hit area, in addition to significant increase in convectively efficient potential energy, condensation height and decrease in the height of free convection – all these favor the happening of the heavy rain,(2) the mergence of meso-βcloud clusters leads to the MCS such fast growth as to produce rainstorm,( 3) the two lines of cumuli in the north and west correspond, separately, to two convergences on the surface wind field, with stronger convergence at their meeting point responsible for such intense development of meso-βcloud cluster as to bring about torrential rains. Analysis of causes as to why MCS propagates to the southwest of MCC indicates the propagation direction depends on the direction and velocity of the two convergences. Finally, the appearance of northerly flow and the metabolism from old into new clouds act as a key factor for triggering the rainstorm. These results can be a useful reference for foreshadowing short-time torrential rains.
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