台风“凡亚比”登陆过程中暴雨MCSs演变及形成机理  

THE EVOLUTION AND FORMATION MECHANISM OF RAINSTORMS MCSS DURING TYPHOON FNANPI LANDING

作　　者：张艳霞[1] 蒙伟光[1] 戴光丰[1] 李春晖[1] 

机构地区：[1]中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室,广东广州510080

出　　处：《热带气象学报》2015年第4期433-443,共11页Journal of Tropical Meteorology

基　　金：行业专项(GYHY201106003);广东省科技计划项目(2012A061400012);广东省气象局科学技术研究项目(2013A04)共同资助

摘　　要：利用大尺度和TBB资料得出1011号台风“凡亚比”环流背景中出现连续性暴雨的大尺度环境概况和主要MCSs活动情况，发现高低空辐散辐合配置的动力结构及强烈的垂直上升运动和丰富的水汽，为暴雨的发生和持续提供了有利的动力和水汽条件；连续性暴雨过程中主要有三个MCSs活动，其中9月20—21日的MCSs持续时间最长、强度最大、暴雨最强。因此，通过观测资料讨论了该MCSs发展演变的特征及基于大尺度资料和中尺度数值模拟结果探讨了其发展演变的机制。结果发现，该MCSs形成、发展、成熟至减弱阶段都处在台风的外围环流中，其中心位于台风移动方向约300～350km处的左前方；从大尺度资料的分析可见，上升运动加强，水汽输送充足，垂直风切变明显增大，不稳定能量的稳定累积及中低层西侧干冷空气的侵入有利于MCSs组织发展。进一步从中尺度数值模拟结果发现，MCSs东、西及北侧的温湿梯度相向发展形成的能量锋区为MCSs的组织发展提供了环境条件和能量，该能量锋区形成于东西两侧温度和湿度梯度的差异，东侧受热带低压登陆降水引起降温增湿，而西侧和北侧受台风外围偏西气流和青藏高原热源共同作用增温减湿。此外，西侧中层干冷空气的侵入也有利于该锋区的存在和维持，更有利于MCSs的发展。正涡度的增长和0～6km垂直风切变大值区的配合，为MCSs的形成发展提供了有利的动力条件。Large-scale circulation and meso-scale convective systems （MCSs） of sustained rainstorms under the background of the typhoon FANAPI are discussed by using large-scale analysis data and TBB data. It is found that on the one hand, a preliminary rainstorm is influenced by a convergent line in the warm sector due to the outer flow of FANAPI and a later rainstorm is affected by weak cold air, and on the other hand, three MCSs are mainly active during the sustained rainstorm, among which the intensity, duration and influence of MCSs on 20-21 September are the strongest, longest and largest, respectively. Therefore, their development and evolution characteristics and formation mechanisms are further investigated using the observations, reanalysis data and numerical simulations. The results show that in the evolution period （formation, development, maturity and weakness） this MCS is about 300-350 km from the moving direction of the typhoon. From the analysis of the large-scale data, we know that enhanced upward motion, sufficient vapor transport and obvious vertical shear appear as the MCSs form and develop. Otherwise, the continuous accumulation of the unstable energy and the intrusion of dry and cold air at the mid- and low-level are in favor of the MCSs development. Furthermore, seen from the simulation of the meso-scale numerical model, an energy frontal zone is formed due to the opposite development of the temperature and humidity gradients in the east, west and north of MCSs. The energy frontal zone provides the conditions and energy for the organization and development of MCSs. The intrusion of dry and cold air at the middle level in the west of MCSs contributes to the existence and persistence of the frontal zone, especially to the development of MCSs The growth of positive vorticity and a large vertical wind shear between 0 and 6krn are well matched, which provides favorable dynamical conditions for the formation and development of MCSs.

关 键 词：台风环流 连续性暴雨 MCSS 数值模拟 机理 

分 类 号：P404[天文地球—大气科学及气象学]