摘要
利用中尺度模式MM5对西北太平洋9617号热带风暴Tom转变温带气旋的变性过程进行了模拟。通过对其变性过程的模拟分析发现:热带风暴Tom与西风槽相互作用,风暴东侧低层暖湿气流与槽前正涡度平流发生耦合有利于气旋发展;槽前暖平流与槽后冷平流使风暴形成具有西冷东暖的热力分布结构,诱使风暴向斜压转变;高空急流入口处右侧的气旋式切变及出口处右侧的反气旋式切变有利于风暴右侧气流上升和左侧气流下沉运动,有利于风暴由正压向斜压性转变;来自风暴西北侧的干冷空气自700hPa附近向风暴中心侵入,使风暴中心暖柱体发生自低层向高层的西北—东南向的倾斜,其暖性特征遭到破坏;由于干冷空气的侵入,低层700hPa分为南北两个暖中心,北侧暖中心北侧出现了明显的暖锋锋生,西南侧另一个暖心附近有冷锋锋生迹象;平流层高值PV异常下传有利于变性后的热带风暴的再次加强。
By using MM5, the transition of Tom （a tropical storm in 1996 in Northwestern Pacific Ocean） from the tropical storm to the extratropical cyclone is simulated. The result shows that： （ 1 ） when Tom entered mid-high latitude of baroclinic zone, it interacted with the 500hPa westerly trough. The coupling of the warm and moist air of low level at the east of the storm and the positive vorticity advection before the trough made it possible for the cyclone to develop. The cold advection after the trough and warm advection before the trough made Tom with cold feature in the west and warm feature in the east. And this thermodynamic structure transformed Tom into a baroclinic cyclone. （2） The cyclonic shear left to the upper-level jet stream entrance and the anticyclonic shear right to the upper-level jet stream exit were favorable for the upward movement right to Tom and downward movement left to Tom, which made Tom transform from a barotrop- ical structure to a baroclinic one. （3） The invasion of the cold and dry air in 700hPa level into Tom＇s warm core made the storm axis tilt NW-SE from lower to upper level and destructed Tom＇s warm core. （4） Because of the invasion of the cold and dry air in 700hPa level, two warm cores appeared. At the north of the northern warm core a significant warm front was born and a cold front seemed to appear near the northwest warm core. （5） The subtropical cyclone＇s re-intensification was related to the downward transmission of high potential vortex from stratosphere.
出处
《气象》
CSCD
北大核心
2009年第8期16-26,共11页
Meteorological Monthly
基金
国家重点基础研究发展计划(973计划)项目(2009CB421504)资助
关键词
热带风暴
变性
模拟分析
tropical storm transformation simulation analysis
