Formation and Development of a Mountain-induced Secondary Center inside Typhoon Morakot(2009)  

作　　者：Xuwei BAO Leiming MA Jianyong LIU Jie TANG Jing XU 

机构地区：[1]Shanghai Typhoon Institute/China Meteorological Administration,Shanghai 200030,China [2]Shanghai Meteorological Bureau、China Meteorological Administration,Shanghai 200030,China [3]Ning bo Meteorological Observatory/China Meteorological Administration,Ning bo 315012,China [4]State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences/China Meteorological Administration,Beijing 100081,China

出　　处：《Advances in Atmospheric Sciences》2018年第9期1160-1176,共17页大气科学进展（英文版）

基　　金：jointly supported by the Key Program for International S&T Cooperation Projects of China(Grant NO.2017YFE0107700);the National Natural Science Foundation of China(Grant No.41405051,41475059,41475060,41675044 and 41775064);the Typhoon Scientific and Technological Innovation Group of Shanghai Meteorological Service

摘　　要：The structural evolution of Typhoon Morakot（2009） during its passage across Taiwan was investigated with the WRF model. When Morakot approached eastern Taiwan, the low-level center was gradually filled by the Central Mountain Range（CMR）, while the outer wind had flowed around the northern tip of the CMR and met the southwesterly monsoon to result in a strong confluent flow over the southern Taiwan Strait. When the confluent flow was blocked by the southern CMR, a secondary center（SC） without a warm core formed over southwestern Taiwan. During the northward movement of the SC along the west slope of the CMR, the warm air produced within the wake flow over the northwestern CMR was continuously advected into the SC, contributing to the generation of a warm core inside the SC. Consequently, a well-defined SC with a warm core, closed circulation and almost symmetric structure was produced over central western Taiwan, and then it coupled with Morakot＇s mid-level center after crossing the CMR to reestablish a new and vertically stacked typhoon. Therefore, the SC inside Morakot was initially generated by a dynamic interaction among the TC＇s cyclonic wind, southwesterly wind and orographic effects of the CMR, while the thermodynamic process associated with the downslope adiabatic warming effect documented by previous studies supported its development to be a well-defined SC. In summary, the evolution of the SC in this study is not in contradiction with previous studies, but just a complement, especially in the initial formation stage.The structural evolution of Typhoon Morakot（2009） during its passage across Taiwan was investigated with the WRF model. When Morakot approached eastern Taiwan, the low-level center was gradually filled by the Central Mountain Range（CMR）, while the outer wind had flowed around the northern tip of the CMR and met the southwesterly monsoon to result in a strong confluent flow over the southern Taiwan Strait. When the confluent flow was blocked by the southern CMR, a secondary center（SC） without a warm core formed over southwestern Taiwan. During the northward movement of the SC along the west slope of the CMR, the warm air produced within the wake flow over the northwestern CMR was continuously advected into the SC, contributing to the generation of a warm core inside the SC. Consequently, a well-defined SC with a warm core, closed circulation and almost symmetric structure was produced over central western Taiwan, and then it coupled with Morakot＇s mid-level center after crossing the CMR to reestablish a new and vertically stacked typhoon. Therefore, the SC inside Morakot was initially generated by a dynamic interaction among the TC＇s cyclonic wind, southwesterly wind and orographic effects of the CMR, while the thermodynamic process associated with the downslope adiabatic warming effect documented by previous studies supported its development to be a well-defined SC. In summary, the evolution of the SC in this study is not in contradiction with previous studies, but just a complement, especially in the initial formation stage.

关 键 词：secondary center OROGRAPHY dynamics Typhoon Morakot （2009） 

分 类 号：P444[天文地球—大气科学及气象学] X171.1[环境科学与工程—环境科学]