近10年江门前汛期大暴雨的特征及合成分析

Characteristics of Torrential Rain During the Annually First Rainy Season in Jiangmen over the Past 10 Years and Composite Analysis

利用地面常规气象站、区域自动气象站及NCEP/NCAR逐6 h 1°×1°再分析资料,对近10年江门前汛期的大暴雨进行分类和合成对比分析。结果表明:江门前汛期大暴雨可分为3类,暖区型是最主要的类型,降水强度最大;锋面型最少,降水强度小但伴有雷雨大风;热带型以强降水为主。锋面型200 h Pa上空存在一条急流轴位于长江中下游的急流带。暖区型500 h Pa上深厚的南支槽对大暴雨的发生和维持有重要作用,热带型与江门附近的低涡活动密切相关。江门上空的水汽通量暖区型和热带型是锋面型的近2倍;锋面型的高空强辐散,是发生雷雨大风的有利天气形势。

Using data from conventional surface weather stations, regional automatic weather stations and NCEP/NCAR 1°×1 ° reanalysis at 6-h intervals, this paper categorizes and runs composite analysis of the torrential rains of the annually first rainy season in the city of Jiangmen over the past 10 years. The result is shown as follows. This type of rain can be divided into three groups. The type of warm sectors （WS） is the most dominant, which is marked with high rainfall intensity, while the type of frontal surfaces （FS） is the least frequent, which is featured by light rainfall intensity but thunderstorm. The third type is dominated by intense rainfall, being tropical in nature （TP）. For the FS type of torrential rain, a 200 hPa jet stream axis was located in the middle and lower reaches of the Yangtze River. For the WS type, a deep trough of the westerlies at 500 hPa was important for the generation and maintenance of the torrential rains in these years. For the TP type, the torrential rains were closely associated with vortexes near Jiangmen. In terms of water vapor flux over the city, the WS and TP types are almost twice as much as the FS type. The intense upper-level divergence with the FS type is favorable synoptic conditions for thunderstorm.