风垂直切变对飓风波尼(1998)结构与强度的影响  

Effects of vertical wind shear on the structures and intensity of Hurricane Bonnie (1998)

作　　者：沈阳[1] 张大林[2] 沈新勇[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,南京2100445 [2]美国马里兰大学大气科学与海洋系,马里兰207422425

出　　处：《气象学报》2012年第5期949-960,共12页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展规划973项目(2009CB421503);国家自然科学基金项目(41075039;41175065);公益性行业科研专项经费项目(GYHY200806009);江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：利用大西洋飓风波尼(1998)的MM5模拟资料(格点距4km),对在风的垂直切变影响下,波尼的结构和强度变化进行了分析。在风的垂直切变影响下,波尼的垂直速度和降水场表现出了明显的1波非对称结构,这种结构与风的垂直切变的强度呈正比;逆切变一侧9—12km高度上通风作用强烈,在破坏波尼暖心的同时,也导致了边界层中低相当位温对波尼核心的入侵,与低层通风路径相比,中层通风对波尼的破坏作用更甚,鉴于在分析时间段内,波尼所经海域平均海温变化不大,可以认为风的垂直切变主导了波尼强度变化;对波尼强度突变现象的分析发现,强度突变源于通风破坏作用的积累,当边界层中低相当位温侵入热带气旋中心的程度超过某一阈值时,气旋强度会突然减弱;其结果显示风的垂直切变造成的动力和热力效应对热带气旋强度的影响都十分重要,而后者更为直接。A 5-day cloud-resolving simulation of Hurricane Bonnie （1998） with the finest grid length of 4 km is used to examine the effects of vertical wind shear （VWS） on hurricane structures and intensity changes. The results show wavenumber-1 asym- metries in the vertical motion and rainfall fields when VWS increases. It is found that the upper-level strong ventilation on the upshear side tends to destroy the warm core in the eye while the VWS-induced intrusion of lower equivalent potential tempera- ture from higher levels into the boundary layer core region plays an important role in weakening the storm. In view of little var- iations of the mean sea-level temperature during the integration period, VWS may be considered as one of the major factors in determining the intensity change of Bonnie. Thus, the results indicate that the thermodynamical impact of VWS could be as sig- nificant as its dynamical impact on Bonnie＇s intensity and intensity changes. The results suggest that higher-level ventilation is more detrimental to hurricane intensity compared to lower-level ventilation.

关 键 词：热带气旋 风垂直切变的动力和热力影响 1波非对称结构 结构和强度变化 

分 类 号：P457.8[天文地球—大气科学及气象学]