台风Haitang(0505)登陆过程地形影响的数值模拟试验

A Numerical Study on the Effects of Orography during the Landfall Process of Typhoon Haitang

以2005年严重影响我国的登陆台风Haitang为研究对象,在用MM5模式成功模拟台风登陆前后路径、强度、降水以及结构特征的基础上,通过地形敏感性试验,分析了地形对台风的影响及其机理。结果表明:台风在经过台湾及其后在福建登陆期间的异常路径是地形诱生低压发生发展的结果;在降水强度上东部沿海特殊地形对台风北侧东南气流的辐合抬升使得暴雨增幅度1倍以上;地形对台风强度也有一定影响,约为4～5hPa。通过对有无地形影响时台风结构的比较发现地形影响主要在低层,使得高度场分裂两个中心,低层台风主体受山脉阻挡在位置上落后于高层。分析还发现台风登陆前夕移动方向西侧相当位温向西倾斜也可能与地形有关。

The landfall process of the typhoon Haitang which affected East China seriously was simulated by using the MM5 model and the track, intensity, precipitation and structure of typhoon were successfully reproduced. Then through the sensitive test,the effects of terrain were analyzed. Results show that the irregular track during the preiod of typhoon passing through Taiwan and later landfalling at Fujian was in relation to the occurring and developing of orthographic impressed depression. The amount of rainfall was enhanced more than one time and the strength of typhoon was weakened 4 to 5 hPa. It is found that the effects of terrain on the structure of typhoon is limited to the low level which make the geopotential height field separate into two centers and cause the center of typhoon at the ow level to be backward in space as compared with the one at the high level. In addition, the phenomenon of the equivalent temperature in the typhoon＇s moving direction inclining to the west on the eve of landfall may be concerned with the terrain.