Estimating lightning channel characteristics of positive narrow bipolar events using intrachannel current reflection signatures
Estimating lightning channel characteristics of positive narrow bipolar events using intrachannel current reflection signatures
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DOI：
10.1029/2007jd008471
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发表时间：
2007-07
影响因子：
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通讯作者：
T. Hamlin;T. E. Light;X. Shao;K. Eack;J. Harlin
中科院分区：
文献类型：
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作者：
T. Hamlin;T. E. Light;X. Shao;K. Eack;J. Harlin
[1]对LosAlamos Sferic阵列(LASA)定位的133个正的窄双极闪电事件进行了研究。之所以选择这些事件，是因为它们的快速电场变化(EFC)记录显示在第一个正峰之后有第二个正峰，这与沿传输线反射阻抗不连续的传播电流脉冲的预期一致。在假设传播速度的情况下，场变化记录中的第一和第二(反射)峰之间的时间差提供了用于估计放电通道长度的直接技术。如果假设信号幅度随时间呈指数衰减，并且反射系数接近于1，则峰值之间的时间差及其幅度的比率得到时间衰减率常数的估计。统计结果表明，S事件的平均峰峰值时间为6.7μ，平均幅度比估计为6.1，幅度衰减率常数为4.0μS。受光速的限制，本研究中典型的正向窄双极事件的通道长度上限约为2公里。
[1] A set of 133 positive narrow bipolar lightning events located by the Los Alamos Sferic Array (LASA) is examined. The events were selected because their fast electric field change (EFC) records show a secondary positive peak, following the primary positive peak, which is consistent with what would be expected for a propagating current pulse reflecting off an impedance discontinuity along a transmission line. With an assumed propagation speed, the time difference between the primary and secondary (reflected) peak in the field change record offers a direct technique for estimating the length of the discharge channel. If the signal amplitude is assumed to decay exponentially with time and that the reflection coefficient is near unity, the time difference between peaks and the ratio of their amplitudes yields an estimate of the temporal decay rate constant. Statistics on the 133 located events examined show an average peak-to-reflected-peak time of 6.7 μs, a mean amplitude ratio estimate of 6.1, and an amplitude decay rate constant of 4.0 μs. Bound by the speed of light, the upper limit on channel length for the typical positive narrow bipolar event (NBE) in this study is shown to be approximately 2 km.