2011年秋季海南强降水过程分析

Analysis of a Torrential Rain Process in Autumn of 2011 in Hainan

对2011年9月下旬至10月上旬,发生在海南的强降水过程特征以及不同的季内周期振荡对其影响进行了分析。结果表明,对此次强降水过程有显著影响的振荡周期为2~7 d和45~90 d。2~7 d的振荡以TD型波动为主,表现为从热带西太平洋-海洋性大陆向西北传播的特征。而45~90d的振荡在9—10月初期间表现为东西双向传播并在海南汇合的特征,有利于在南海北部出现持续的对流环流系统。该次海南强降水过程发生在La Nina事件期间,热带印度洋和热带西北太平洋为大范围的暖异常,位于南海北部的季风槽和强劲的西南季风有利于热带气旋的生成和海南强降水过程的发生及维持。

From late September to early October in 2011, several tropical cyclones passed by Hainan, causing severe rainstorm disaster. This paper analyzesthe synoptic features of heavy precipitation and the im- pact of different intraseasonal oscillationson in this process. The results show that both the 2-7-day and 45- 90-day oscillations play important roles in the heavy rainfall event. The 2-7-day oscillation manifested as tropical depression （TD-type） wave and propagated northwestward from the maritime continent to tropical western Pacific. The 45-90-day oscillation propagated both eastward from northern tropical Indian Ocean and westward from northern tropical western Pacific, and then converged at South China Sea in the period from September to October, favoring the persistent convective circulation over the northern South China Sea. The heavy rainstorm process occurred during a La Nifia event. The wide area of warm sea surface temperatures in the tropical Indian Ocean and the tropical western Pacific, the monsoon trough located in northern part of the South China Sea and strong westerly are all conducive to the genesis of tropical cyclone, the development and maintenance of Hainan＇ s heavy rainstorm process.