西北太平洋生成热带气旋的年代际变化

为了分析热带气旋年代际变化的特征和造成这种变化的原因,利用西北太平洋编号台风资料对1949～2003年55 a的西北太平洋热带气旋特点进行分析,发现西北太平洋生成的热带气旋不管是频数还是生成位置都存在明显的年代际变化,根据热带气旋频数的年代际变化,把研究的55 a分成低频时期(LFP)和高频时期(HFP)分别加以考察.结果发现:热带气旋生成的高低频时期海气条件存在明显的差异,HFP的海温、对流、涡散度和切变条件都有利于西北太平洋热带气旋的生成,而LFP则明显存在物理量场的相反异常.这表示HFP的海气环境相比LFP更有利于热带气旋生成,说明了变化的海气条件是引起热带气旋频数和生成位置年代际变化的主要原因.

Interdecadal variability of tropical cyclone formation in the northwest Pacific

In order to r esearch the char acterist ics and cause of interdecadal v ar iability of T ropical Cyclones ( TCs) act ivity over the Nor thw est Pacif ic, data of ser ial typhoons in the nor thw estern Pacific during the 55-y r period 1949-2003 w ere used. T w o kinds of periods were identif ied in this study : High Frequency Period ( HFP) and Low Frequency Per io d ( LFP) . Significant dif ferences in the number of T Cs between HFP and LFP were found. The result s show that the area of T Cs g enesis in HFP ex tends mor e to the east than that in LFP. The atmospheric and oceanic circumstances in HFP enhance the genesis of T Cs in comparison w ith those in LFP. It is sug gested that the v ar iability of the oceanic and atmo spheric co ndit ions are the main causes for the interdecadal variability o f TCs.