2008年台风森拉克引起上层海水降温的机制

采用区域海洋模型(regional ocean modeling system,ROMS)模拟了2008-2009年西太平洋的水动力过程,重点关注台湾东侧台风影响的海域,研究2008年13号强台风森拉克引起的上层海水降温机制.通过对模拟结果的分析,认为30m以上海水的降温主要是扩散作用即夹卷效应造成,而30m以下海水的降温主要由垂向对流即上升流造成.海水从下层50～800m的深度处辐聚上升,在表层50m以浅辐散流出.台风过后海水温度逐渐恢复.研究认为:台风会加强海水的垂向湍流/混合,导致最大Ekman泵吸水深下探,使得下层的低温海水更有可能到达表层.

Mechanism of the Ocean Water Cooling Caused by Typhoon Sinlaku in 2008

The study of the oceanic response to a hurricane has both scientific and economic significance to the national benefic and so on.In this paper,the physical processes are simulated by using ROMS(regional ocean modeling system) in the western Pacific Ocean from 2008 to 2009.The object is to study the mechanism of ocean water fast decreasing when the typhoon Sinlaku passes the east to Taiwan in 2008.The results of the model indicate that the process of the ocean water cooling is caused by diffusion,i.e.entrainment,at upper 30 m water column,and below that is mainly due to vertical convection,i.e.upwelling.The results show that the ocean water converges and upwells between depth 50 m and 800 m and diverges in the surface layer above 50 m depth.After the typhoon event,seawater temperature will gradually recover.In this study,it is considered that the strong wind stress of typhoon can cause the high vertical viscosity rates,which will deep the function of the Ekman pumping,and the cold water below the thermocline can upwell easily.