2011年02号台风“桑达”快速增强过程分析

Analysis on the Rapid Intensification Process of Super Typhoon Songda( 1102)

以2011年2号超级台风"桑达"为例,根据中国气象局(CMA)和美国联合台风警报中心(JTWC)的热带气旋(TC)资料,定义其近中心24 h风速变化达到17.5 m/s为TC快速增强的阈值。进一步合成分析了"桑达"快速增强前后96 h的环境要素场变化特征。结果表明:"桑达"底层水汽通量的突然增强为其经历快速增强过程及以后缓慢增强过程提供了有利条件;其北侧的高空槽和东北侧副热带高压的增强终止了其快速增强过程;环境风速和风向切变是影响"桑达"经历快速增强过程的重要因子。大强度的北西风切变使得"桑达"强度减弱;风向切变由东南方向转为西北方向时,以北西气流为载体的冷空气破坏了其环流结构,使其快速增强过程终止。

Using the tropical cyclone best track data of China Meteorological Administration （CMA） and Joint Typhoon Warning Center？ （ JTWC）, the thresholds of rapid intensification （RI） process of Songda （ 1102 ） as 17. 5m/s is defined, which represent the 24-h overwater intensity changes. Then, a total of 96 hours synthetic analy- sis, including 24 hours before and 48 hours after RI process, is given out. Results show that, the rapid intensifica- tion of the vapor flux in the bottom atmosphere is favorable for Songda to undergo RI process. And its RI process is terminated by the intensification of the Subtropical High and troughs, respectively in the northeast and northern region of Songda. The shear of wind speed and direction is another key factor for Songda to undergo RI process. Songda＇ s intensity can be weakened by the large northwest wind shear. When the wind shear change from southeast to northwest, the cold air in northwest airstream can be destroyed the circulation structure of Songda, which can end the RI process.