2001年台风“榴莲”生成前期对流“热塔”的数值模拟  

NUMERICAL SIMULATION OF HOT TOWERS DURING PRE-GENESIS STAGE OF TYPHOON DURIAN(2001)

作　　者：张文龙[1] 崔晓鹏[2] 王昂生[2] 宗志平 

机构地区：[1]中国气象局北京城市气象研究所,北京100089 [2]中国科学院大气物理研究所,北京100029 [3]国家气象中心,北京100081

出　　处：《热带气象学报》2008年第6期619-628,共10页Journal of Tropical Meteorology

基　　金：公益性行业(气象)科研专项经费项目(GY200706004);北京市科技计划课题(Z0006279040191);国家自然科学基金面上项目(40505012)共同资助

摘　　要：积云对流热塔(hot tower)对台风生成具有重要意义,但以往对热塔的认识一直停留在概念性语言描述上。采用PSU-NCAR MM5模式对2001年台风"榴莲"在正压环境条件下的生成过程,进行了成功的高分辨率(6 km)显式数值模拟。利用模式输出的高时空分辨率资料,对与台风"榴莲"生成相关的对流热塔进行了比较细致的考察,分析了成熟热塔的结构图像,并通过实例证实了Montgomery(2006)提出的热塔偶极涡度对概念模型。其主要特征包括:(1)热塔内部垂直上升运动强烈,从边界层开始,直达甚至穿透对流层顶,最大上升速度中心位于对流层中上层;(2)在地面到200 hPa之间,具有强雷达回波特征的对流云塔垂直耸立,边界光滑;(3)热塔的侧边界相当位温面十分陡立,基本呈中心对称分布;(4)热塔远比周围环境空气温度高,高温扰动中心可达4 K以上,位于最大上升速度中心上方附近;(5)所有热塔都伴随有偶极涡度对,在垂直剖面图上偶极涡度对呈现多样性,以单偶极和双偶极为主要形式,有时也存在三偶极的形式;(6)偶极涡度对进一步与偶极涡旋对对应;(7)垂直速度和正涡度柱在对流层中上层基本不重合;(8)热塔内水平风速剧烈地向垂直方向扭转。另外,初步分析了偶极涡度对的形成机制,偶极涡度对的产生归因于水平涡管向垂直涡管的剧烈扭转。Convective hot towers have very important contributions to the genesis of typhoons. However, only conceptual descriptions and few conceptual charts of structures of hot towers are available until now. The genesis of typhoon Durian（2001）, in tropical barotropic environment, has been explicitly simulated successfully with the finest grid size of 6 km by using PAU/NCAR MM5. In this study, the structure of hot towers during pre-genesis of Durian is examined by using high-resolution simulation output. The charts of the structure of hot towers are obtained and the vorticity dipole structure discovered from ideal experiments by Montgomery（2006） is re-discovered from real case simulation of typhoons. The results show that, （1） there are intense upward motions in hot towers starting from the planetary boundary layer and reaching or penetrating the tropopause, the maximum upward velocity is in the middle-upper troposphere; （2） There are ＂cloud towers＂ with strong radar reflectivity between ground and 200 hPa, with smooth boundary; （3） The plane of equivalent potential temperature lies vertically and symmetrically near hot towers＇ lateral boundary; （4） Hot towers are much warmer than their environment with the maximum positive temperature difference of 4 K, locating just above the maximum updraft; （5） Each hot tower shows a vorticity dipole structure with one or two or three dipoles in vertical cross sections; （6） The vorticity dipole is further related with the vortex dipole; （7） The upward motions do not superpose the positive vorticity, especially in middle-upper troposphere; And （8） in hot towers, the horizontal wind turns drastically to the vertical direction. The simple analysis of the mechanism of vorticity dipoles tells that it is the drastically tilting of the horizontal vorticity that generates the vorticity dipole.

关 键 词：对流热塔 结构特征 偶极涡度对 涡管扭转 

分 类 号：P444[天文地球—大气科学及气象学]