Properties of the unusually short pulse sequences occurring prior to the first strokes of negative cloud‐to‐ground lightning flashes
Properties of the unusually short pulse sequences occurring prior to the first strokes of negative cloud‐to‐ground lightning flashes
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第一次负云对地闪电之前发生的异常短脉冲序列的特性
DOI：
10.1002/2014gl060913
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发表时间：
2014
影响因子：
5.2
通讯作者：
L. Uhlir
中科院分区：
文献类型：
--
作者：
I. Kolmašová;O. Santolík;T. Farges;W. Rison;R. Lan;L. Uhlir
我们分析了在负云地闪电第一次回击之前发生的脉冲序列的宽带磁场和电场测量。我们的观测发生在距离雷暴几十公里的地方，但我们也报告了第一次同时观测到400公里外的初步击穿脉冲。它们的振幅达到相应回击峰值的50%，并且在序列期间通常降低约40%。相邻脉冲之间的典型时间间隔为几十微秒。我们观察到一个异常短的持续时间的中风前活动（1-7毫秒）首次报告在夏季雷暴，与低高度的启动（3 - 4公里）。一个非常快的传播速度（~106米/秒）可能保持整个预行程的过程。一个可能的解释可以基于一个假设，即在观测到的雷暴云中存在异常强的负电荷源。
We analyze broadband magnetic and electric field measurements of pulse sequences occurring prior to first return strokes of negative cloud‐to‐ground lightning flashes. Our observations take place a few tens of kilometers from the thunderstorm but we also report the first simultaneous observations of preliminary breakdown pulses from a distance of 400 km. Their amplitudes reach up to 50% of the corresponding return stroke peak and typically decrease by ~40% during the sequences. A typical time interval between neighboring pulses was several tens of microseconds. We observe an unusually short duration of the prestroke activity (1–7 ms) reported for the first time during a summer thunderstorm, with a low height of initiation (3‐4 km). A very fast propagation speed (~106 m/s) is probably maintained for the entire prestroke process. A possible explanation can be based on a hypothesis of unusually strong negative charge sources in the observed thundercloud.