浙南闽北登陆台风发生区域性暴雨增幅的环境场特征分析

Analysis of atmospheric circulation characteristics of regional rainstorm reinforcement associated with typhoons making landfall in northern Fujian and southern Zhejiang

采用1950—2015年在浙南闽北登陆的台风历史个例及其降水资料,将台风路径分为西行类和北上类来探讨浙江省受不同路径台风影响时,发生区域性暴雨增幅或不发生增幅的形势场和物理量场特征及台风暴雨增幅落区规律。结果表明:台风登陆西行和北上路径发生区域性暴雨增幅或不发生暴雨增幅环境场特征均有明显的差异,增幅型台风登陆前后对流层中低层建立从南海、台湾东部到浙江沿海并伸入浙江内陆的E-SE急流和水汽通道,θse平流呈东暖西冷的结构,台风中心呈高层辐散、低层辐合的结构;若有弱冷空气入侵,暴雨增幅强度更强、范围更大,暴雨增幅落区明显向浙中北部地区伸展。无暴雨增幅型台风对流层中低层从南海到台湾没有明显的偏南风急流,中低层浙江沿海的SE风急流轴及水汽通道偏北偏东,强度偏弱,没有伸入浙江内陆;浙江处于大陆暖气团的SE侧,浙江沿海无明显的暖平流;高层无辐散或弱辐散、低层弱辐合。

Using the historical records of typhoon landing in northern Fujian and southern Zhejiang during 1950-2015, the typhoon path is divided into groups moving westward and northward after landing. The atmospheric circulation and physical parameter features, separating whether there is a regional typhoon rainstorm reinforcement or non-occurrence in Zhejiang, are extracted under the two different types path typhoon influence, and the distribution of rainstorm reinforcement is also discussed. The results show that it has clear difference between rainstorm reinforcement occurrence and non-occurrence in the westward and northward track typhoons. When regional typhoon rainstorm reinforcement occurred in Zhejiang, before and after the landfall of typhoon, the water vapor channel and E-SE jet in the mid-low troposphere have extended from the South China Sea, east of Taiwan to the coast of Zhejiang and into Zhejiang inland. There is a high-level divergence and low-level convergence structure near typhoon center, and with an east warm and west cold pseudo-equivalent temperature advection field structure. If there is weak cold air intrusion, rainstorm reinforcement intensity is stronger and larger, and rainstorm reinforcement falling area is stretched to the north of Zhejiang. The non-reinforcement rainstorm typhoon has no obvious southerly jet in the South China Sea to Taiwan or SE jet axis, and the low-level water vapor channel over coastal Zhejiang is to the north and east, not into Zhejiang inland, and the strength is weaker. Zhejiang is in the SE side of the continental warm air mass, and there is no obvious warm advection in the Zhejiang coast,also no high-level divergence nor weak high-level divergence and low level weak convergence near typhoon center.