低涡过程对流云和降水结构特征及其环境条件分析  

Structural Characteristics of Convective Clouds and Precipitation in a Low Vortex Weather Event and Its Surrounding Conditions

作　　者：雷蕾[1] 周毓荃 毕宝贵 

机构地区：[1]北京市气象台,北京100089 [2]国家气象中心,北京100081

出　　处：《气象科技》2009年第4期398-406,515,共10页Meteorological Science and Technology

基　　金：国家"十一五"科技攻关项目(2006BAC12B07)资助

摘　　要：利用遥感及加密观测资料详细分析了2005年6月25～26日一次低涡过程对流云和降水的结构特征，并利用NCEP再分析资料以及实况风场资料分析了其形成的有利条件。分析表明：此次低涡过程中出现的中尺度对流云团（MCC）经历了十几小时的发展演变，云顶亮温低达-90℃，导致了局地暴雨出现，对流云和降水的分布有很好的对应但同时具有显著的时空分布不均匀性。对流云内部高空存在冰晶的大值区，云水含量也比周围环境丰富，冰晶下落过程中通过碰粘其它冰晶、碰冻云水导致了云内的可降水增多，播撒-供应机制起主要作用。而对流降水的“双峰“廓线结构表明暖雨过程非常强。此次过程有形成强对流非常有利的环境：强西南低空急流水汽输送和水汽辐合与高空偏西风急流的相互作用为对流云团和强降水的形成提供水汽和不稳定条件；低层不稳定区域上强垂直上升运动则提供了不可缺少的动力条件；中尺度辐合系统的形成是此次强对流产生的直接原因。An analysis is made of the structural characteristics of the convective clouds and precipitation on 25 to 26 June in 2005, by using a variety of observation and remote sensing data and the favorable surrounding conditions by using NCEP reanalysis data and real wind data. The results show that some mesoscale convective cloud clusters underwent the development of more than 10 hours, and TBB decreased to- 90 degrees, which led to the inhomogeneous rainfall distribution in both time and space. The convective clouds had prominent micro-physical structural characteristics, which had the high content of ice particles at the upper level and more plentiful cloud water. The seeder-feeder mechanism was playing the major role. The ＂double-peek＂ profile structure of convective precipitation shows that the warm rain process was very strong in MCC. The surrounding conditions were very useful for the formation of MCC and the convective storm： the water vapor transmitted and converged by the strong south-west low level jet and the interaction of high and low level jet provided vapor and unstable conditions; the strong vertical upward motion in the unstable areas was the necessary dynamic condition; the middle-scale convergence system directly caused the convective process.

关 键 词：低涡 中尺度对流云团 暴雨 结构特征 环境条件 

分 类 号：P458.2[天文地球—大气科学及气象学] TU753.1[建筑科学—建筑技术科学]