2008年西北太平洋热带气旋活动异常特征及成因分析

ANALYSIS OF THE ANOMALOUS ACTIVITIES OF TROPICAL CYCLONES OVER THE WESTERN NORTH PACIFIC IN 2008

2008年西北太平洋热带气旋活动的特点:(1)初台异常偏早;(2)生成热带气旋异常偏少,但登陆热带气旋异常偏多,登陆热带气旋与生成热带气旋比例高;(3)从热带气旋的生成源地来看,2008年的热带气旋生成位置明显偏西。2008年热带气旋生成年频数异常偏少的主要原因:2008年仍处在生成热带气旋偏少的气候背景下,对流层低层盛行东风距平高层盛行西风距平,季风槽位置异常偏西,不利于热带气旋的生成。

There are three obvious characters of the activities of tropical cyclones over the western North Pacific in 2008：（1） The first typhoon landing into China is especially earlier than the normal year.（2） the number of tropical cyclones generating in the Pacific Northwest and the south China was far less than normal year but the number of tropical cyclones landing in China was more than normal year.（3） The location of tropical cyclones generating was westward off the average point.That the main reason causing decrease of tropical cyclone number in 2008 was,tropical cyclone activities were still in less than climatic average,and the east wind was stronger than normal in the low troposphere but the west wind was stronger than normal in the high troposphere,and the monsoon trough was singularly westward.