NUMERICAL SIMULATION STUDY OF THE INNER-CORE STRUCTURES AND THE MECHANISM FOR INSHORE STRENGTHENING OF SOUTH CHINA SEA T
An explicit simulation with a fine mesh at intervals of 6 km is used to explore the inner-core structures of Vongfong (0214). The dynamic mechanism for the inshore strengthening of Vongfong is examined. It is found as follows. (1) The radius of maximum wind of the axisymmetric structures of the typhoon decreased with height during its mature stage. When Vongfong was inshore,the strongest low-layer inflow located in front of it and the outflow was to the rear of it,which was just reversed from the Atlantic hurricanes and other Pacific typhoons. (2) The dynamic and thermodynamic fields were highly asymmetric in structure. Convection was stronger in the northwest quadrant of the typhoon than in the southeast; the strongest convective cloud bands were consistent with the maximum wind region. During its strengthening stage,it was cold west of and warm east of the eye in the lower layer but warm in the west and cold in the east of the mid-upper layer. During its mature stage,a warm-core structure was evident in the lower and middle-upper layer. (3) The interactions between a mid-latitude cold low in the middle-upper troposphere and the typhoon were responsible for the latter to strengthen inshore. Firstly,the outer circulation of the cold low entered the typhoon from the middle troposphere when an outer cold airflow from the cold low flowed into the northwest quadrant of the typhoon so that geopotentially instable energy increased and convection developed. Secondly,the downdrafl in the cold low was just the corresponding branch of the secondary circulation of the typhoon system; when the cold low weakened while moving south,the typhoon strengthened inshore. Due to the CISK mechanism,these two phenomena might be realized.
作 者： LI Jiang-nan HUANG Xiao-dong WANG Gang FONG Roi-kun LI Wei-biao 作者单位： LI Jiang-nan,WANG Gang,LI Wei-biao(School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510275 China)HUANG Xiao-dong(Jiangmen Meteorological Bureau,Jiangmen 529020 China)
FONG Roi-kun(Macao Geophysical and Meteorological Bureau,Macao China)
刊 名： 热带气象学报(英文版) 英文刊名： JOURNAL OF TROPICAL METEOROLOGY 年，卷(期)： 2009 15(1) 分类号： P444 关键词： dynamic meteorology typhoons numerical simulation structure