南海季风槽影响下热带气旋暴雨增幅的研究

Research on the Enhancement of Tropical Cyclone Rainstorm Influenced by Monsoon Trough of South China Sea

使用NASA的热带测雨卫星TRMM资料、常规气象观测降水资料、NCAR/NCEP-2再分析资料及NCEP全球数据同化系统(GDAS)资料,分析研究南海季风槽伴随热带气旋登陆华南而导致热带气旋暴雨强烈增幅的事实,并根据观测事实提出季风槽伴随热带气旋登陆华南的定义。结果表明:(1)南海季风槽伴随热带气旋登陆导致热带气旋降水强烈增幅的天气现象发生在盛夏季节;(2)环流背景表现为副热带高压带状西伸,稳定控制华中一带;同时,西南季风活跃,南海季风槽位于南海北部之时;(3)热带气旋登陆后的填塞消亡时间因为季风槽的伴随而大大延长,热带气旋云系有再生、加强和扩展现象;(4)伴随登陆的季风槽对热带气旋暴雨无论是空间,时间,还是强度上均有强烈增幅作用,热带气旋暴雨在季风槽南侧延伸,尺度可达1500～2500km。

The TRMM data, conventional observation data, NCAR/NCEP-2 reanalysis data and global data assimilation system （GDAS） data are taken to investigate the strong enhancement of tropical cyclone rainstorm when tropical cyclone accompanied with South China Sea monsoon trough lands in South China. Based on the observational facts, the event that the tropical cyclone accompanied with a monsoon trough lands in South China is defined. The results show that strong enhancement of tropical cyclone rainstorm usually happened in July to September. The synoptic- climatic characteristics are that subtropical high intensifies zonal spreading westerly and dominates over middle China. Meanwhile, South China Sea monsoon is in its active period, South China Sea monsoon trough locates over north of South China Sea. The lifetime of tropical cyclone after its landing is prolonged due to the accompanying South China Sea monsoon trough. Cloud system of tropical cyclone has a process of regeneration, strengthening and spreading. Tropical cyclone rain-storm gains strong increment on rainfall intensity and tropical cyclone lifetime. The rainfall area stretches on the south of the monsoon trough about 1500-2500km.