利用中国气象局上海台风研究所整编的2001年《热带气旋年鉴》、美国NCEP最后分析FNL 1°×1°全球格点资料以及日本气象厅云顶亮温(TBB)资料等,对0116号台风Nari自北向南穿越台湾岛过程中的结构强度变化进行诊断分析,结果表明:(1)登陆过程中Nari云系结构从圆形变为半圆形,其环流西部对流云团旺盛,而东部为无云或少云区.Nari在岛上期间一直维持这种非对称结构特征.(2)在穿越台湾岛过程中,Nari西部环流内低空急流轴从其北侧逆时针延伸至南侧.一方面,切向风角动量的增加和传播有利于台风涡旋环流的加强,另一方面,低空急流附近的水汽通量辐合及急流轴左侧较强的正涡度区,有利于气旋性环流的长久维持.(3) Nari的结构强度变化与台湾岛地形及海峡效应有密切关系.Nari环流西部位于台湾岛迎风一侧上升运动加强,而Nari环流东部位于背风一侧上升运动则受抑制,对Nari形成半圆形非对称对流分布起积极作用；而台湾海峡的狭管效应加速台风通过气流,有利于Nari环流西部低空急流的形成和增强.(4)动能收支诊断表明,Nari登陆过程中动能的主要来源是动能制造项,水平辐合运动也对其提供动能.%Diagnostic analysis was performed on Typhoon Nari (2001), which exhibited abnormal structural and intensity changes when crossing Taiwan Island, on the basis of the 2001 Tropical Cyclone Yearbook compiled by the Chinese Meteorological Administration, the United States National Center for Environmental Prediction (NCEP) final (FNL) 1°X 1° global grid data, and temperature of black body (TBB) data from the Japan Meteorological Agency. The following results are reported: (1) Nari's cloud structure changed from circular to semicircular with convective clouds developing in the western area and dissipating in the eastern area of typhoon circulation during its landfall process and maintained such an asymmetric structure over the island. (2) When crossing the island, a lower-layer jet (LLJ) stream in Nari's western circulation strengthened and extended counterclockwise from north to south. The increase in angular momentum of the tangential wind was favorable for strengthening vortex circulation. In addition, the water vapor flux convergence near the LLJ and the strong positive vorticity on the left of the LLJ axis helped to maintain the cyclonic vortex. (3) Taiwan topography, including the Taiwan Strait, had a pronounced effect on the structure and intensity of Nari. The windward slope-forced lifting intensified ascending air flow in Nari's western circulation; however, the sinking on the leeward side restrained the convection in its eastern circulation. These factors were primarily responsible for the formation of Nari's semicircular asymmetric structure. Moreover, the channel effect of Taiwan Strait benefited the strengthening and stretching of the LLJ stream in Nari's western periphery. (4) A diagnosis of kinetic energy budgets revealed that the kinetic energy of Nari was generated from the solenoid effect. In addition, horizontal convergence movement provided kinetic energy for Typhoon Nari during its landfall process.
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