桂林雷暴时空分布特征分析

根据1957-2010年桂林所辖13个站点的逐日地面雷暴观测资料,对近50年桂林地区初雷日、终雷日,以及雷暴的年、季、月、日、时变化特征,雷暴的空间分布等进行气候统计分析。结果表明,桂林市年平均雷暴日数为59.4d,属高雷区;全市南部县年雷暴日比北部县多,北部地区初雷日最早都在1月7日,南部都是1月4日,初雷日最晚为4月11日,各地最晚终雷日基本都在12月30日;每月均有发生雷暴的可能,6月为高峰月,最少的是12月;一天中雷暴出现的时间变化也呈现单峰型特点,主峰区在14：00-17：00,深夜和凌晨是雷暴活动的低谷;由于气候变化等原因,20世纪80年代中期以后雷暴日总体呈逐渐下降趋势。

Spatial and Temporal Distribution Characteristics of Thunderstorm in Guilin

Based on the observed information from 1957 to 2000 about daily thunderstorm in thirteen sites in Guilin,statistical analysis was conducted on the first thunder day and the last thunder day in a year,and spatial and temporal（year,season,month,day and hour） distribution characteristics.The results indicated that Guilin was a high thunderstorm region and the annual thunderstorm day was 59.4 d.In Guilin,counties in the south experienced more thunders than those in the north.The earliest first thunder day is usually on January 7th in the north,but on January 4th in the south.The latest first thunder day is April 11th and the latest last thunder day in most regions is December 30th.Thunderstorm might happen in every month,with most chance in June and least in December.Temporal change of thunderstorm for a day was in single-peak type,peak period was from 14：00 to 17：00 and trough period was late at night and in the small hours.Because of climate change,thunderstorm day is declining after middle of the 1980s.