登陆热带风暴Bilis(2006)暴雨特征及其可能原因

Rainfall Characteristics of Bilis(2006)and Its Possible Formation Mechanism

利用NCEP/NCAR 1°×1°格点再分析资料、FY-2C TBB(black bright temperature)资料及中国740站降水资料,对0604号强热带风暴Bilis登陆后的暴雨特征及其可能原因进行诊断分析,结果表明:(1)Bilis登陆过程中强降水中心位于风暴中心西北侧沿岸,主要影响福建和浙江两省;进入内陆后强降水中心向风暴中心以西转移,最后在风暴中心西南侧聚集,主要影响广东东北部、福建、江西和湖南南部。(2)西北太平洋副热带高压的稳定少动为Bilis陆上西行过程中产生持续性降水提供了稳定的背景场。(3)Bilis西南部季风环流的发展增强为Bilis登陆后强降水的产生提供了必要的水汽条件。(4)涡合并和自激增长形成的中尺度系统与风暴涡旋的相互作用,是Bilis登陆后产生强降水的可能机制。

The rainfall distributive characteristics of strong tropical storm Bilis（2006） after the landfall and its possible formation mechanism are analyzed based on the NCEP/NCAR 1°×1° grid reanalysis data,the TBB data from FY-2C, and the precipitation data at 740 observational stations in China. The main results are as follows ： （ 1 ） The strong precipitation centers of Bilis lay in the Northwest side of its surface center during its landfalling, and the heavy rain mainly occurred in Fujian and Zhejiang province;and after the landfall, those centers shifted to the West side and latter to the southwest side of Bilis＇ surface center,and the heavy rain occurred in the Northeast of Guangdong Province,Fujian Province, Jiangxi Province, and the South of Hunan Province. （ 2 ） The stable and motionless Northwest Pacific subtropical high provided a stable large scale circulation background field for Bilis＇ persistent precipitation during its westward movement over land. （3）The development and strengthening of the Southwest monsoon to the Southwest of Bilis greatly enhanced the moisture transfer to Bilis＇ precipitation areas. （4）The interaction between storm vortex and meso- and small-scale vortices,which were resulted from the mergence of vortices and self-excitation, might be the possible formation mechanism for Bilis＇ strong precipitation after its landfall.