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两类登陆热带气旋的大尺度环流特征分析
引用本文:周伟灿,王灿伟.两类登陆热带气旋的大尺度环流特征分析[J].南京气象学院学报,2009,32(4):474-482.
作者姓名:周伟灿  王灿伟
作者单位:1. 南京信息工程大学大气科学学院,江苏,南京,210044;南京信息工程大学气象灾害省部共建教育部重点实验室,江苏,南京,210044
2. 南京信息工程大学大气科学学院,江苏,南京,210044
基金项目:江苏省气象灾害重点实验室资助项目 
摘    要:采用动态合成分析方法,对1970-2006年登陆后北上类TC(tropicalcyclone)和西行类TC各7个样本做动态合成分析和诊断,结果表明:(1)北上类TC在背景场长波槽前北移靠近中纬度斜压锋区,通过吸附运动使TC低压并入西风槽,而西行类TC背景场没有长波槽,离中纬度斜压锋区较远;(2)北上类TC登陆时存在西南低空急流水汽输送带,当其强度减弱后,TC东南侧存在东南暖湿气流作为补充,而西行类TC减弱后逐渐与之分离,且不存在东南暖湿气流作为补充;(3)北上类TC高层辐散区与高空急流边界靠近,因此增强了其向东北方向的辐散,低层由于高层动量下传,加强了低空西风,从而使TC低压环流维持,而西行类TC离高空急流边界较远;(4)北上类TC从中纬度斜压锋区获取斜压能量,其环流垂直切变增强,相对涡度差负值增大,在高空TC中心散度由大变小后又由小变大的过程中,TC发生了变性,而西行类TC没有环境能量补给,逐渐填塞消亡。因此,当一个TC登陆后,其预报移动方向、水汽输送状况、与斜压锋区的关系以及高空辐散气流等特征,可以作为初步判定登陆TC将减弱消亡还是将变性加强的可能原因。

关 键 词:登陆TC  大尺度环流  动态合成分析  变性

Large-Scale Circulation Characters of Two Categories of Landfalling Tropical Cyclones
ZHOU Wei-can,WANG Can-wei.Large-Scale Circulation Characters of Two Categories of Landfalling Tropical Cyclones[J].Journal of Nanjing Institute of Meteorology,2009,32(4):474-482.
Authors:ZHOU Wei-can  WANG Can-wei
Institution:ZHOU Wei-can, WANG Can-wei(1. School of Atmospheric Sciences,NUIST,Nanjing 210044,China; 2. Key Laboratory of Meteorological Disaster of Ministry of Education,NUIST,Nanjing 210044 ,China)
Abstract:Dynamic composite and diagnostic analyses were performed for the northward/westward moving tropical cyclones (TC) of 7 cases each after their landfall on the southeast coast of China in 1970--2006. The different characters of large scale circulation for the two categories of landfalling TCs are found. The results show that the north moving TCs after landfalling gained the baroclinic energy and westerly momentum from the mid-latitude jet stream, which is favorable to the maintenance of the TCs ver land, while the westward moving TCs did not gain the energy and momentum due to far away from the mid-latitude baroclinic front zone. The north moving TCs had moisture supply from the south-west low-level jet when landfalling, and from the southeast warm/wet flow after its decaying;yet the westward moving TCs got away from the southwest low-level jet after its decaying, and also did not have moisture supply from the southeast warm/wet flow. The vertical shear of the circulation of the northward moving TCs increased after their gain of baroclinic energy from the mid-latitude baroclinic front zone, the upper level divergence over the center of the TCs experienced a strong-weak-strong evo-lution process, I. E. The TCs experienced an extratropical transition process, however the westward mov-ing TCs did not have energy supply from the environmental flow field, gradually decaying. The results of tiffs study could help the operational forecast on the extratropical transition of a tropical cyclone over land after its landfalling.
Keywords:landfall tropical cyclone  large-scale circulation  dynamic composite  extratropical transition
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