强台风“菲特”(1323)极端降水研究进展

Research progress on extreme precipitation of Typhoon FITOW(2013)

台风暴雨灾害是台风三类灾害(暴雨、大风、风暴潮)之首,而台风极端降水是暴雨灾害的直接原因,对台风极端降水的研究有利于增强对台风极端降水机理的认识和提高极端降水的预报水平。强台风“菲特”(1323)具有登陆强度历史罕见、降雨强度大、影响范围广、引发灾害重等特点,本文对“菲特”极端降水特征及其形成机理研究进行了回顾和总结。“菲特”的强降水过程主要分为两个阶段,造成了杭州湾一带和浙闽交界处两个强降水中心。“菲特”极端降水之所以产生,源于环境因子、地形和内部条件多尺度相互作用:环境因子涉及双台风作用、弱冷空气侵入、台风倒槽、垂直风切变和高空急流等,其中“丹娜丝”台风外围偏东气流源源不断的水汽输送是“菲特”极端降水形成的关键物理因子;山脉等地形增幅作用是浙江余姚等地出现历史性强降水的重要原因;水汽辐合和凝结与霰的融化和对流区雨滴的迁移是暴雨增幅重要的内部因素。

Typhoon rainstorm disaster tops the three types of disasters(rainstorm,gale,storm surge)of typhoon and extreme precipitation of typhoon is the direct cause of rainstorm disaster.The study on extreme precipitation of typhoon is helpful to enhance the understanding of its mechanism and to improve the forecast of extreme precipitation.The strong Typhoon FITOW(2013)has the characteristics of strong intensity as landing,intense precipitation,wide range of influence,and severe disaster caused by it.In this paper,the characteristics and formation mechanism of the extreme precipitation of Typhoon FITOW are reviewed and summarized.The heavy precipitation process of FITOW is mainly divided into two stages,resulting in two heavy precipitation centers in the area of Hangzhou Bay and the junction of Zhejiang and Fujian provinces.The extreme precipitation of FITOW is due to the multi-scale interaction of environmental factors,terrain,and internal conditions.Environmental factors involve the effect of double typhoons,the intrusion of weak cold air,typhoon inverted trough,vertical wind shear,and upper-level jet stream,among which the continuous water vapor transport by the easterly jet outside of Typhoon DANAS is the key physical factor for the extreme precipitation of FITOW;the topographic enhancement effect is an important reason for the rarely seen heavy precipitation in Yuyao,Zhejiang;the convergence and condensation of water vapor,the melting of graupel,and the migration of raindrops in convective areas are the important internal factors for the rainstorm amplification.