基于LLS的雷电流波头陡度时间和概率分布特征

Temporal and Probability Distribution Characteristics of Wave Front Gradient for Lightning Current Based on LLS

为研究雷电流波头陡度分布特征,以满足雷电防护工程设计、雷击事故分析等雷电灾害防御工作需要,根据湖北省2007-2013年雷电定位系统（Lightning Location System,LLS）监测的雷电流波头陡度资料,采用数理统计方法,对雷电流波头陡度的年、季、月、日变化及累积概率和概率密度分布进行了统计分析。结果表明,正闪、负闪和总闪电的年平均陡度分别为12.0、11.0和11.1 k A/μs;雷电流波头陡度夏季最大,冬季最小,秋季比春季大。1年中,正闪和负闪电波头陡度最大值分别出现在7月和6月,最小值均出现在12月。日中,正闪电陡度最小值与负闪电陡度最大值均出现在6-8时,正闪电陡度最大值和负闪电陡度最小值分别出现在23-0时和13-14时。95%的正闪和负闪电的波头陡度分别不大于31.4和21.1 k A/μs,正闪与负闪电波头陡度累积概率差异明显,负闪电波头陡度累积概率分布比正闪电更集中。雷电流波头陡度主要分布在2-20 k A/μs,正闪和负闪电陡度概率密度最大值出现在8 k A/μs左右。采用最小二乘法进行回归拟合,正闪、负闪和总闪电波头陡度累积概率实测曲线与拟合曲线基本一致,相关系数均在0.999 5以上。

In order to study distribution of gradient for lightning current wave front,to meet with demands of lightning protection engineering design,lightning stroke accident analysis and the lightning disaster prevention,the authors utilize the gradient of lightning current wave front data collected by the LLS（ lightning location system） from 2007 to 2013 to analyze its annual variation,seasonal variation,monthly variation and daily variation,and work out its cumulative probability and cumulative probability density by mathematical statistics method. The results show that the average gradient of wave front for positive lightning,negative lightning and the total number of lightning are 12. 0 k A / μs,11. 0k A / μs and 11. 1 k A / μs,respectively. In a year,the gradient of wave front is the greatest in summer,the smallest in winter,and it is greater in autumn than in spring. The greatest gradient of wave front for positive lightning and negative lightning appear in July and June,and the smallest gradient for both kind of lightning occur in September. In a day,the smallest wave front gradient for positive lightning and the greatest gradient for negative lightning occur at 6am to 8am.What＇s more,the greatest gradient for positive lightning and the smallest gradient for negative lightning occur at 23 pm to24pm and 13 pm to 14 pm. 95% of wave front gradient for positive lightning and negative lightning are less than 31. 4k A / μs and 21. 1 k A / μs. The cumulative probability for wave front of positive lightning has sharp distinction with the negative one,that is,the cumulative probability of negative one is more concentrated than the positive one. The wavefront gradient of lightning current are mainly distributed at 2-20 k A / μs,the maximal cumulative probability densities for positive lightning,negative lightning occur about 8k A / μs. By using least-square regression fitting method,the fitted curve of cumulative probability of wave front gradient for positive lightning,negative lightning and the total number of lightning are basically consistent with the measured one,and the correlation coefficient is larger than 0. 999 5.