乐清以北登陆台风“利奇马”和“阿贝”造成温州强降水差异的环境场特征分析

Analysis of environmental field characteristics for the difference of heavy rainfall in Wenzhou caused by typhoon“Lekima”and“Abe”landed on north of Yueqing

利用常规观测资料、加密自动站资料、中国气象局(CMA)热带气旋最佳路径数据集和欧洲气象中心ECMWF逐6 h的0.125°×0.125°资料,分析乐清以北登陆的1909号超强台风“利奇马”和9015号台风“阿贝”影响温州强降水的分布特征,以及造成温州南北暴雨强度差异的环境场特征。结果表明:(1)“利奇马”和“阿贝”台风的环境场特征相似,副高平均脊线位置高,研究区内台风主体没有与冷空气结合,降水主要由台风螺旋雨带造成;(2)台风登陆前动力场均存在中高层弱辐合和低层弱辐散,且东冷西暖的θse平流结构有利于强降水的维持,中高层水汽通量散度强度大于-4×10^(-5) g·cm^(-2)·hPa^(-1)·s^(-1)的区域与暴雨落区的形态和位置对应良好,中低层Q矢量辐合区和大暴雨落区对应良好;(3)台风过程累积雨量与台风中心距离和地形高度具有显著相关关系,温州北部雨量增幅比南部大;(4)该路径造成温州南北部降水差异大,北部暴雨量级比南部大、降水持续时间比南部长,北部乐清和永嘉交界的迎风坡出现超历史极值降水现象概率大。

By using the conventional observation data,encrypting automatic station data,the best path data set of the tropical cyclone of China Meteorological Administration(CMA)and the 0.125°×0.125°data of ECMWF every six hours,the distribution characteristics of heavy rainfall in Wenzhou cased by 1909 super typhoon“Lekima”and 9015 typhoon“Abe”landed on north of Yueqing,and the characteristics of environmental field causing the difference of rainstorm intensity between North and South of Wenzhou werecomparatively analyzed.Results show that:(1)the environmental characteristics of“Lekima”and“Abe”are similar.The mean ridge of subtropical anticyclone locates at high latitude.Typhoons are not combined with cold air,and the precipitation is mainly caused by spiral rain belt of the typhoons;(2)before typhoons land,the weak divergence in the middle and upper atmosphere and weak convergence in the lower atmosphere appear.θse greater than 355 K and the structure ofθse advection cold in east and warm in west are in favor to maintain heavy rainfall.The area where the water vapor flux divergence intensity in the middle and upper layers greater than-4×10^(-5) g·cm^(-2)·hPa^(-1)·s^(-1) corresponds well with the shape and location of the rainstorm area,and the Q vector convergence area in the middle and lower layerscorrespond well with the rainstorm area;it is significant correlation of the accumulated rainfall from the shortest distance between the station and the typhoon center and the terrain height;(4)different from the southern and northern of Wenzhou,the kind of typhoon landing path causes precipitation.In the north,the rainstorm magnitude is larger and the duration of precipitation is longer.In the windward slope between Yueqing and Yongjia,the occurring probability of historical extreme precipitation phenomenon is big.