武汉地区云地闪电特征及防护效率研究

采用武汉地区2006年3月至2009年2月云地闪电资料,统计分析了武汉地区云地闪电特征及其直击雷防护效率,为该地区的雷电防护工程设计和雷击风险评估提供参考依据。统计分析表明,武汉地区年平均云地闪电次数为45693次;负闪电占闪电总数的96.0%,平均负闪电强度为32.6 kA;正闪电占闪电总数的4.0%,平均正闪电强度为38.3 kA。4-8月闪电占全年闪电总数的96.9%,其中7-8月闪电占全年闪电总数的70.8%,9月至次年3月闪电仅占全年闪电总数的3.1%。正、负闪电强度主要集中在10-50 kA,平均陡度为12 kA/μs左右。通过统计分析,拟合出适合武汉地区大于某一雷电流幅值累计概率方程。武汉市新洲区西南部与黄陂区东南部交接地区和江夏区东部地区是闪电高密度中心,年平均闪电次数在8.5次/km~2以上。武汉地区建筑物直击雷保护范围按照1、2、3类防雷类别设计时,其绕击率分别为1.3%、3.3%和11.5%,反击率分别为0.1%、0.2%、1.6%。

Lightning Characteristics and Protective Efficiency in Wuhan Area

The lightning characteristics and protective efficiency in the Wuhan area are analyzed statistically,based on the cloud-ground lightning data from March 2006 to February 2009.The results indicate：the annual mean number of cloud-ground lightning flashes in the Wuhan area is 45693;the negative lightning accounts for 96.0%of the total and the average negative lightning intensity is 32.6 kA; the positive lightning accounts for 4.0%of the total and the average positive lightning intensity is 38.3 kA.The number of lightning flashes from April to August accounts for 96.9%of the annual total,and that from July to August accounts for 70.8%,that from September to March of next year for 3.1%.The positive and negative lightning intensites are mostly within the range of 10 kA to 50 kA,and the average steepness is about 12 kA/jus.The accumulation probability equation for the lightning current bigger than certain amplitude is formulated by several statistical methods.The border areas of the southwestern Xinzhou and southeastern Huangpi and the eastern Jiangxia are high-density lightning centers,where the annual mean lightning number of lightning flushes is above 8.5 /km~2.According to the three-grade lightning protection category,the shielding failure rate is 1.3%,3.3%and 11.5%,and the counter-attack rate is 0.1%、0.2%、1.6%,respectively.The results can be used as references in lightning protection engineering design and lightning risk assessment.