广西雷暴活动特点分析

根据气象台站的雷电观测记录，分析广西境内雷电活动的基本特点，认为广西是我国雷暴最多的地区之一，与中南半岛多雷区相连，是以马来半岛、澳洲北部为中心的雷暴高发区的向北延伸。2月份，伴随着副热带西风急流的南压，初雷自北向南开始；终雷出现在10月中下旬，与副热带高压脊线的南撤、东南季风撤出大陆的日期相一致。ITCZ的影响是广西成为多雷区的主要原因。平均雷暴日数的峰值就出现在ITCZ影响广西最多的8月份。地形对雷电活动有明显影响，广西地形的弧形山结构明显地改变着雷暴活动的空间分布。十万大山的抬升、来自南海、琼州海峡和北方的气流不同形式的辐合以及海岸线走向产生的“壁角效应”共同作用使东兴的雷暴日数和雨量一样居全区之冠。季风资料分析表明，南海强夏季风年广西的雷电活动比弱夏季风年频繁。

AN ANALYSIS OF THE CHARACTERISTICS OF THUNDERSTORM ACTIVITY IN GUANGXI

The basic features of thunder activity is presented by analyzing observational data. It is pointed out that Guangxi is an area where thunders occur frequently, which is linked to the Indo-China Peninsula, the northern extent of the Malay Peninsula-North Australia high frequency thunderstorm region. In February, the first thunderstorm occurs from south to north with subtropical high southward moving. The last thunderstorm occurs at late October, which coincides with the southward moving of subtropical high ridge and withdrawing of southeast monsoon from the continent. The main factor affecting thunderstorm in Guangxi is ITCZ, and the peak value of average thunderstorm days are in August when ITCZ affects Guangxi the most. Topography plays a significant role in thunderstorm activity as well. The arc mountain structures affect evidently the spatial distribution of thunderstorm activity. The lifting effect of the Shiwan Mountains on the air flows, the convergence of the flows from the South China Sea and the Qiongzhou strait, and those from north, and the corner effect caused by cost trend make Dongxing the most thunder days and precipitation in Guangxi Province. The thunderstorm activity frequency is higher in strong monsoon year than in weak year.