中文摘要：

2009年西北太平洋及南海海域共生成23个风暴以上等级的热带气旋（TC）,比常年偏少,但登陆我国的频数（10个）多于常年,台风以上等级TC的活动强于常年。TC源地较常年偏西,并且季节性纬向迁移特征明显,而经向位移并无显著异常,在南海海域生成的TC比例（26.1%）远高于气候均值;路径以西行和西北行为主,登陆华南TC较多。登陆台风在我国造成强烈的降水影响。进一步的分析表明：2009年TC源地随季节东移的趋势主要与热带太平洋的海气耦合变化即Walker环流上升支和对流层高低空扰动动能增强区以及低层南风涌逐渐东移有关;TC偏西路径为主、登陆华南较多主要由西北太平洋局地环流特征尤其是TC活动期副热带高压呈带状的形势所决定;TC个体平均强度偏强与西北太平洋局地扰动动能和高层辐散增强相联系。

英文摘要：

Only 23 tropical storms occurred over the western North Pacific and the South China Sea during the tropical cyclone（TC） season 2009.Although the frequency of TCs is less than normal years,there are more TCs,ten out of twenty three,making landfall in China,typhoons are also more active than normal. The region of TC formation seems to be further west to the normal and shifts eastward from the beginning to the end of season.More TCs,about 26.1%,were formed in the South China Sea.Most of these TCs moved westward or northwestward,and the primary area attached by the landfall TCs is the South China. Landfall TCs bring extreme heavy rains.Further analysis shows that the TC genesis area and its migration are closely related to the evolution of the coupled air-sea system of the tropics,that is,the updraft leg of Walker circulation shifts eastward together with the area of enhanced turbulent kinetic energy in both lower and upper troposphere and southerly surge.The primary tendency of TC tracks,as well as the high frequency of TCs＇ making landfall on South China,is dominated by the local pattern of general circulation, especially the dominant belt-like subtropical high.Meanwhile,the intense activity of individual storm is closely related to the enhanced regional turbulent kinetic energy in low levels and divergence in 200 hPa.