超强台风“威马逊”与“达维”进入北部湾强度变化对比分析

Comparative analysis of intensity changes between super typhoons Rammasun (1409) and Damrey (0518) during the period of entering the Beibu Gulf

利用常规气象资料、NCEP 1°×1°再分析资料,采用天气学诊断分析方法,对超强台风"威马逊"(1409)和"达维"(0518)登陆进入北部湾前后强度变化特征差异进行对比分析,结果表明:(1)500 h Pa副高快速加强,850 h Pa季风急流和越赤道气流汇合卷入到台风环流中,台风移向的下游区域高低空(200—850 h Pa)垂直风切变小,南海北部海温偏高等是"威马逊"和"达维"登陆海南岛前在近海突然加强的有利条件。(2)从琼州海峡进入北部湾,摩擦消耗小,是"威马逊"进入北部湾后,强度下降小,仍维持超强台风级别的主要原因;而从海南岛中部西移进入北部湾,摩擦消耗大,是"达维"进入北部湾后,强度下降大,从超强台风降为台风级别的主要原因。(3)动能收支诊断分析显示,地形摩擦对动能的耗散主要集中在边界层内(800 h Pa以下),"威马逊"在超强台风阶段耗散作用最大,进入北部湾之后摩擦耗散减小,而"达维"则因横穿海南岛进入北部湾动能的摩擦耗散较大。

Using conventional meteorological data and NCEP/NCAR lo by lo reanalysis data, the differences of intensity characteristics between super typhoon Rammasun （1409） and Damrey （0518） were investigated during the period of landfall and entering the Beibu Gulf. The results show that （1） the rapid strengthening of the subtropical high, the monsoonal and cross-equatorial inflows, weak downstream zonal vertical wind shear, and high temperature in northern South China Sea were key factors of two super typhoons sudden strengthening. （2） Super typhoon Rammasun has a path of crossing Qiongzhou Strait into the Beibu Gulf, which exhibit weak friction and slight intensity decreasing, and is favorable to maintain its super typhoon grade. In contrast, super typhoon Damrey crossed Hainan Island into the Beibu Gulf, leading to great intensity decreasing. （3） The kinetic budget shows that kinetic friction dissipation caused by terrain is concentrated in the boundary layer （below 800 hPa）. Rammasun has a considerable decrease of kinetic energy after into the Beibu Gulf, while Damrey has greater kinetic dissipation during the period of crossing Hainan Island.