我国华南江南春季雷暴气候特征分析

基于我国华南江南地区274个基本地面气象观测站数据、全国闪电定位数据以及欧洲中心的全球大气再分析数据(ERA-Interim)，对1981—2017年华南江南地区的春季雷暴日采用经验正交函数分解方法(EOF)，并与气象要素场做回归分析。得出以下主要结论:(1)我国华南江南地区春季雷暴活动高发区主要在广西东部至广东西部；其高峰期在下午18:00和凌晨4:00左右，且大多数雷暴活动持续时间不超过3 h；山区雷暴活动主要在傍晚至夜间；平原雷暴活动主要在白天，高峰在17:00及06:00前后；(2)华南江南地区的雷暴活动存在着3~5年的短周期和16年左右的长周期变化；(3)雷暴日距平EOF分析的前3个主成分累计方差贡献达到72.3%。按其向量场的方差贡献分型，Ⅰ型表现为华南江南雷暴活跃特征呈现较统一的变化规律。深厚西南低涡槽前、上干下湿的水汽层结、上冷下暖的温度层结为华南江南地区发生大范围雷暴天气提供良好的动力、水汽和位势不稳定条件，是华南江南雷暴活跃异常的主要模态；Ⅱ型表现为从华南南部到江西与浙江南部有一条西南-东北向、下宽上窄的雷暴活跃正距平异常区，而两侧为负距平异常区。其环流特征表现为温度整层偏冷，水汽整层偏湿，而西南槽前动力抬升有利于水汽抬升凝结触发对流形成雷暴；Ⅲ型表现为华南和江南地区雷暴活跃特征呈南北反位相异常，其分界线在26 °N附近。其环流特征表现为较强的干冷空气南下与南方暖湿空气在南岭山区对峙形成异常的垂直环流圈。在其上升支，低层干冷空气被卷入中高层使得中高层暖湿空气凝结释放潜热形成对流，造成华南地区多雷暴发生，而江南地区处于垂直环流的下沉支，整层湿度偏干，造成江南地区雷暴相对偏少。 

ANALYSIS ON THE CLIMATOLOGICAL CHARACTERISTICS OF THUNDERSTORMS IN THE SOUTH AND SOUTHEAST OF CHINA IN SPRING

Based on data of 274 meteorological observation stations, national lightning location and ERA-Interim global reanalysis from 1981 to 2017, the methods of EOF and regression are used to analyze the spring thunderstorm day in the south and southeast of China. The results are shown as follows: (1) Eastern Guangxi to western Guangdong is a main, active area of thunderstorm in the south and southeastern China; The peak period of thunderstorm activity is around 18:00 and 04:00, and most thunderstorms last for no more than 3 hours; in the mountainous areas, the thunderstorms are mainly from evening to night, while, in the plains, they are mainly during the daytime, and the peaks happen around 17:00 and around 06:00. (2) The thunderstorm activity has a short period of 3~5 years and a long period of 16 years in the south and southeast of China. (3) The cumulative variance contribution of the first three principal components of the thunderstorm days anomalous EOF analysis reached 72.3%. According to the variance contribution, Type I shows a uniform change pattern of the thunderstorm activity in the south and southeast of China, and a deep southwest vortex trough, wet and dry water vapor stratification and cold and warm temperature stratification provide sufficient power, water vapor and potential instability for large-scale thunderstorms that happened in the southeast and south of China. This is the main model of thunderstorm activity in these areas. Type Ⅱ shows a positive anomaly thunderstorm activity zone from the south of China to Jiangxi and then to the south of Zhejiang, and two negative anomaly zones on its both sides, with a whole column of cold and wet atmosphere, and the dynamic uplift of the southwest trough is beneficial to the condensation of water vapor to trigger convection. Type Ⅲ shows that thunderstorms activity is north-south anti-phase anomalies in the south and southeast of China, and the boundary line is around 26 °N, with a northern strong dry cold air encountering a southern warm and humid air to form an anomalous vertical circulation circle over the Nanling Mountains area. In its ascending branch, low-level dry and cold air is entrained in the middle and upper levels, causing the mid- and high-level rising warm and humid air to condense and release latent heat to cause convection in the south of China, while in its sinking branch of the vertical circulation, the whole layer atmosphere over the south of the Yangtze River is dry, and thunderstorms are relatively little.