台风“云娜”(2004)的数值模拟:眼墙对流与环境风切变的关系  

A numerical simulation of typhoon Rananim(2004):The relationship between eyewall convection and the environmental vertical wind shear

作　　者：聂高臻[1] 谈哲敏[1] 仇欣[1] 

机构地区：[1]南京大学大气科学学院中尺度害性天气教育部重点实验室,南京210093

出　　处：《南京大学学报（自然科学版）》2010年第3期317-327,共11页Journal of Nanjing University（Natural Science）

基　　金：国家重点基础研究发展规划项目(2009CB4251500);国家自然科学基金(40828005;40921160382);国家科技支撑计划重点项目(2006BAC02B03);国家公益行业科研专项(GYHY200706020)

摘　　要：本文利用中尺度数值模式WRF,模拟了台风"云娜"(2004)在近海加强并登陆的过程.模拟的台风强度、路径、登陆时间和台风登陆前眼墙回波、水平风场的非对称性特征,以及登陆时台风眼墙的回波结构与实际观测结果相近.台风中不同高度的环境风切变方向有较大差异:登陆前风切变在低层指向西北,中层指向东北,高层指向东南.涡旋中心倾斜主要受风切变影响;同时眼墙对流发展与风切变方向有着较好的对应关系,而与涡旋倾斜的一致性较差.登陆前后,不同高度的环境风切变方向指向相应高度上的上升运动中心.地形敏感性试验表明地形高度对环境风切变的影响较小,而对台风涡旋倾斜有较大影响.In this study,the Weather Research and Forecasting model（WRF） is used to simulate the intensification and landfall of typhoon Rananim（2004）.The simulated storm agrees well with observations in terms of track,intensity and the time of landfall.Comparison between simulation and available radar/satellite observations,it is found that the simulation also successfully captured the asymmetric structures in the radar echo and surface wind field,and especially the eyewall echo structure during Rananim＇s landfall.The simulation shows that the directions of environmental vertical wind shear vary remarkably with height.Before its landing,the vertical shear vector in the lower level is northwestward;while in the middle level,the shear vector is northeastward and southeastward in the upper level.The corresponding vortex tilt is mainly governed by vertical wind shear.Generation of convection is not signifieantly affected by vortex tilt but agrees well with the direction of vertical shear.Before and after landing,the vertical shear vectors point directly to the updraft center of eyewall in different levels.Sensitivity experiment suggests that variation of terrain height would make more difference on vortex tilt than on vertical wind shear.

关 键 词：环境风切变 眼壁对流 涡旋倾斜 地形 登陆台风 

分 类 号：P435[天文地球—大气科学及气象学]