合肥地区地闪特征

祝宝友;陶善昌;刘亦风

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高原气象 ›› 2002, Vol. 21 ›› Issue (3) : 296-302.
论文

合肥地区地闪特征

  • 祝宝友;陶善昌;刘亦风
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Characteristics of Ground Flashes in Hefei Region

  • ZHU Bao-you;TAO Shan-chang;LIU Yi-feng
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摘要

根据观测资料,分析了利用闪电辐射场信号大容量采集系统观测到的合肥地区地闪回击特征。结果表明,每次地闪回击数频率分布并不表现为简单的指数衰减特征,回击数在5次以下的各回击数出现频率几乎相当,单次回击地闪的比重只有约15%。平均地闪回击数为4.2次,观测到的最大回击数为16次。地闪回击归一化电场强度近似服从对数正态分布。169例首次回击平均电场强度为9.3 V·m-1(归一化到100 km,下同),485例继后回击的平均电场强度只有4.5 V·m-1。480例继后回击与首次回击场强之比平均为0.6,有18%地闪过程至少有一次比首次回击强的继后回击。相邻两次回击间隔时间呈现对数正态分布特征。观测到的最短回击间隔为1.6 ms,约30%的回击间隔>100 ms,在40~100 ms之间的回击间隔比重约为50%。回击间隔时间与间隔前后回击相对强弱之间存在系统性的变化趋势,当两次回击间隔在40 ms以下时总是以‘前强后弱’的回击组合占主导地位,相反,当回击间隔时间增加到>100 ms时,约55%的回击间隔表现为‘前弱后强’的回击组合。

Abstract

Characteristics of return strokes in Hefei Area measured by a VLF/VHF radiation recording system is presented.The number of strokes per flash does not show a exponential decay distribution.However,flashes whose stroke number are below 5 to occur almost equally to each other and single stroke flashes account for about 15% of total flashes.The average number of strokes per flash is 4.2 and the maximum number ever measured is 16.Normalized(to 100 km) strength of return strokes distributes log normally.For 169 first return strokes the geometric mean of initial electric field peak normalized to 100 km is 9.3 V·m-1,the same value for 485 subsequent strokes is 4.5 V·m-1 and the most probable range is between 2 and 4 V·m-1.On a statistical base the subsequent stroke is weaker than the first stroke,while it is interesting to note that about 18% of ground flashes have at least one subsequent stroke whose initial peak is greater than the peak of the first stroke.The interstroke interval distributes log normally with the minimum value of about 1.6 ms.About 30% intervals are larger than 100 ms and intervals between 40 ms and 100 ms account for about 50%.The ratio of the field peak of two successive return strokes varies systematically with the time interval between them:Intervals less than 40 ms are dominated by the fact that the larger stroke occurs first,while about 55% of intervals more than 100 ms are featured by the preceding return stroke being weaker than the successive one.

关键词

地闪过程 / 回击峰值场强 / 回击次数 / 回击间隔时间

Key words

Lightning discharge / Initial field peak / Number of strokes pe

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导出引用
祝宝友;陶善昌;刘亦风. 合肥地区地闪特征. 高原气象. 2002, 21(3): 296-302
祝宝友;陶善昌;刘亦风. Characteristics of Ground Flashes in Hefei Region. Plateau Meteorology. 2002, 21(3): 296-302

参考文献

基金

国家自然科学基金项目(49775252);中国科学院知识创新项目(KZCX2-201)共同资助
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