台风倒槽内β中尺度低涡及特大暴雨的数值模拟  

NUMERICAL SIMULATION OF EXTREMELY HEAVY RAIN AND MESO-βSCALE LOW VORTEX IN INVERTED TYPHOON TROUGH

作　　者：姜勇强[1] 王昌雨[1] 张维桓[1] 陈中一[1] 

机构地区：[1]解放军理工大学气象学院,南京211101

出　　处：《气象学报》2003年第3期312-322,共11页Acta Meteorologica Sinica

基　　金：空军KJ990 99资助课题

摘　　要：对 2 0 0 1年 7月 6～ 7日上海嘉定特大暴雨及β中尺度低涡进行大、中尺度分析 ,认为特大暴雨是在西太平洋副热带高压的西北侧、北部西风槽与南部台风倒槽相连的形势下形成的。利用改进的区域 η坐标模式 (REM)对这一过程进行了数值模拟 ,发现降水先于 β中尺度低涡形成 ,强降水是在“风速偶”之间的强辐合作用下触发的。探讨了“风速偶”特别是弱风中心形成的原因。根据模式输出的高时空分辨率物理量场对 β中尺度低涡与特大暴雨的形成进行分析 ,探讨了它们形成的机制 ,结果表明 β中尺度低涡的形成是由于强降水使气柱增暖加强了低空原有的正涡度的情况下形成的 ,低涡与降水存在正反馈机制 。Large and meso scale analyses are made for extremely heavy rain and meso β scale low vortex occurring in Jiading of Shanghai during 6-7 July, 2001.It is shown that extremely heavy rain happened for the instance of interaction among inverted typhoon trough and westerly trough and continent cold high and west Pacific Ocean subtropical high, especially for the instance of westerly trough linking together with inverted typhoon trough at northwest side of west Pacific Ocean subtropical high. Numerical simulation is made using a 21 level improved REM model for this course. The model is that we improved using vertical varying distance difference scheme and Blackadar high resolution PBL scheme and improved its horizontal resolution from 1°×1° to 0.25°×0.25°,etc. The model uses E grid, and Betts convective parameterized scheme. The terrain is made using Wallace envelope topography. The simulation shows that, not only the typhoon center and the inverted trough are well simulated, but also the extremely heavy rain and meso β scale low vortex. The northeast to southwest forecast rain area is similar to observation, only the forecast extremely heavy rain center is located southeast far about 30km from observation. It is found that precipitation occurred earlier than meso β scale low vortex, and the strong convergence between `wind speed mate' triggered strong precipitation. The formative reasons of `wind speed mate' are discussed, especially the weak wind speed center. The strong wind speed center is formed by the interaction between subtropical high and typhoon, and the weak center must be formed by col field. The control experiment shows that the formation of the `wind speed mate' and meso β scale low vortex and the overlapping area of positive vorticity and negative divergence is closely related to the special terrain and underlying surface character of Shanghai area. The meso β scale low vortex and extremely heavy rain are analyzed using high time and space resolution model output physics fields, and

关 键 词：特大暴雨 台风倒槽 数值模拟 Β中尺度低涡 

分 类 号：P458.121[天文地球—大气科学及气象学] P445