ANALYSIS OF STRUCTURE EVOLUTION AND ENVIRONMENTAL CONDITIONS OF TROPICAL CYCLONES OVER THE WESTERN NORTH PACIFIC DURING EXTRATROPICAL TRANSITION  

作　　者：危国飞 朱佩君 江佳 刘会军 

机构地区：[1]Fujian Meteorological Station, Fuzhou 350001 China [2]Department of Earth Sciences, Zhejiang University,Hangzhou 310027 China [3]Department of Chemical and Environmental Engineering, University of California Riverside, Riverside CA 92521 USA

出　　处：《Journal of Tropical Meteorology》2017年第1期15-24,共10页热带气象学报（英文版）

基　　金：National Natural Science Foundation of China(40805018);National Basic Research Program of China(2013CB430104);Special Fund for Scientific Research in the Public Interest(GYHY201106035)

摘　　要：Fifty-eight extratropical transition(ET) cases in the years 2000-2008, including 2,021 observations(at 6-hour intervals), over the western North Pacific are analyzed using the cyclone phase space(CPS) method, in an effort to get the characteristics of the structure evolution and environmental conditions of tropical cyclones(TCs) during ET over this area. Cluster analysis of the CPS dataset shows that strong TCs are more likely to undergo ET. ET begins with the increment of thermal asymmetry in TCs, along with the generation and intensification of an upper-level cold core, and ends with the occurrence of a lower-level cold core. ET lasts an average duration of about 28 hours. Dynamic composite analysis of the environmental field of different clusters shows that, in general, when TCs move northward,they are gradually embedded in the westerlies and gradually transform into extratropical cyclones under the influence of the mid-and higher-latitude baroclinic systems. As for those TCs which complete ET, there is always much greater potential vorticity gradient in the northwest of them and obvious water vapor transport channels in the environment.Fifty-eight extratropical transition（ET） cases in the years 2000-2008, including 2,021 observations（at 6-hour intervals）, over the western North Pacific are analyzed using the cyclone phase space（CPS） method, in an effort to get the characteristics of the structure evolution and environmental conditions of tropical cyclones（TCs） during ET over this area. Cluster analysis of the CPS dataset shows that strong TCs are more likely to undergo ET. ET begins with the increment of thermal asymmetry in TCs, along with the generation and intensification of an upper-level cold core, and ends with the occurrence of a lower-level cold core. ET lasts an average duration of about 28 hours. Dynamic composite analysis of the environmental field of different clusters shows that, in general, when TCs move northward,they are gradually embedded in the westerlies and gradually transform into extratropical cyclones under the influence of the mid-and higher-latitude baroclinic systems. As for those TCs which complete ET, there is always much greater potential vorticity gradient in the northwest of them and obvious water vapor transport channels in the environment.

关 键 词：extratropical transition of tropical cyclone cyclone phase space cluster analysis composite analysis 

分 类 号：P444[天文地球—大气科学及气象学]