青海高原2008-2016年云地闪特征分析

Characteristics analysis of the cloud-to-ground lightning in Qinghai Province during 2008-2016

利用2008-2016年青海省云地闪监测网资料,分析了云地闪特征。结果表明:2008-2016年青海高原云地闪次数呈现逐年增加的趋势;各年正云地闪比例在10.1%~19.8%之间,平均正云地闪比例为15.0%,且春季和秋季明显高于夏季;总云地闪平均电流强度为30.3 kA,正云地闪平均电流强度为50.1 kA,负云地闪平均电流强度为27.2 kA;负云地闪月平均峰值电流呈现双峰双谷的分布特征,正云地闪月平均峰值电流呈现单峰单谷的特征;正负云地闪电流强度频次分布均呈现正态分布的特征;云地闪电流强度幅值频次累积概率分布服从IEEE Std 1243-1997推荐的雷电流累积概率分布模型;云地闪平均陡度为7.3 kA·us^(-1),正云地闪平均陡度为7.8 kA·us^(-1),负云地闪平均陡度为7.2kA·us^(-1);云地闪在夏季(6-8月)发生较为频繁,占总闪电的81.0%,其次是秋季(9-11月),占总闪电的13.5%,夏季和秋季云地闪电占全年闪电的94.5%;云地闪的日变化呈现单峰单谷的特征;总云地闪年均最大密度达10.4次·km^(-2)·a^(-1),正云地闪年均最大密度达2.1次·km^(-2)·a^(-1),负云地闪年均最大密度达10.3次·km^(-2)·a^(-1),总云地闪和负云地闪的密度高值区在西宁、大通和湟中一带,正云地闪的密度高值区在玛沁和同德一带。

To recognize the characteristics of lightning in Qinghai Province based on the cloud-to-ground lightning data collected from 2008 to 2016,the characteristics of cloud-to-ground lightning were analyzed by statistical approach in this article. It was revealed that there was an increase trend from 2008 to 2016 in Qinghai Plateau,the annual positive lightning ratio had been in between 10. 1% and 19. 8% with an average of 15%,and the percentage in spring and autumn had been higher than that in summer observably. The annual average total cloud-to-ground lightning intensity was 30. 3 kA,including the average of positive lightning intensity of 50. 1 kA and the average of negative lightning intensity of 27. 2 kA. The gradient of cloud-to-ground lightning was 7. 3 kA ·us^-1 in average,and 7. 8 kA ·us^-1 for positive lightning and 7. 2 kA ·us^-1 for negative lightning. The cloud-to-ground lighting frequency during summer（June-August） had been very frequent,accounting for 81%,followed by that in autumn（September-November）,accounting for 13. 5%. Daily variation of cloud-to-ground lightning had showed a single peak and single valley. The annual mean maximum cloud-to-lighting density was 10. 4 times per square kilometer per year with an annual maximum positive cloud-to-lighting density of 2. 1 times per square kilometer per year and an annual maximum negative cloud-to-lighting density of 2. 1 times per square kilometer per year. Spatially,the high-value center of total cloud-to-lightning and negative cloud-to-lightning were in Xining,Datong and Huangzhong,while the high-value center of positive cloud-to-lightning was in Maqin and Tongde.