摘要
2006年夏季西太平洋热带气旋活动主要有如下特征：1）生成时间具有明显的阶段性,且强度强,登陆中国数偏多。2）登陆热带气旋有其各自特点。例如“碧利斯”影响范围大、降水强度大、持续时间长;“桑美”风速大,登陆后迅速减弱。作者针对上述2个特点进行了初步分析。研究发现：1）2006年6月27日-8月31日,来自印度洋的热带西风增强并东推延伸及115-140°E的越赤道气流的加强都有利于热带气旋的生成,并在西太平洋副热带高压北移、季节内振荡（Madden-Julian Oscillation,简称MJO）的湿位相、高低层纬向风切变弱和菲律宾以东地区热带辐合带（Intertropical Convengence Zone,简称ITCZ）对流活跃等背景条件配合下,使热带气旋在这一阶段频发。2）2006年夏季水汽含量与供给对登陆热带气旋的影响显著。“碧利斯”和“桑美”的水汽来源不同是造成这两个登陆热带气旋明显差异的重要原因。
The characteristics of tropical cyclones over the western North Pacific during summer in 2006 are as follow：1） The intensity of tropical cyclones over the Northwest Pacific in the summer 2006 is stronger than that in the normal years.These tropical cyclones tend to cluster temporally around some period（27 June—31 August）.Therefore more tropical cyclones landed on China to make heavier disasters during this period.2） The most damaging landing typhoons are Bilis and Saomai,the former influenced a great area,brought heavy precipitation,and lasted for a long time;the latter brought strong wind,and decayed very soon.Some primary researches are performed in terms of the two characteristics.The circulation features are compared between tropical cyclone clustering period and no cyclogenesis period.The results show that：during the first period（1—26 June）,the Western Pacific Subtropical High was more south than the climate average one,and the Intertropical Convergence Zone（ITCZ） is also more south.Near 5°N,the vertical shear of zonal wind（200—850 hPa） is small.These circulation conditions resulted in the few formation of tropical cyclones.On the contrary,during the second period（27 June—31 August）,both the Western Pacific Subtropical High and the ITCZ moved north.The weak vertical shear of zonal wind is just over the ITCZ.The cyclogenesis favors these atmospheric circulation conditions.The Indian Monsoon extends east or not,and the intensity of the cross-equatorial flow may also play a very important role on cyclogenesis.The reason why Bilis and Saomai have different features is also researched.The results show that the difference between Bilis and Saomai are derived from different vapor channels and origin.
出处
《气候与环境研究》
CSCD
北大核心
2007年第6期738-750,共13页
Climatic and Environmental Research
基金
国家重点基础研究发展规划项目2004CB418303
上海台风所台风研究基金2006STB01
国家自然科学基金资助项目40523001
关键词
热带气旋
热带辐合带
副热带高压
tropical cyclone,intertropical convergence zone,western pacific subtropical high
