A closer examination of terrestrial gamma‐ray flash‐related lightning processes
A closer examination of terrestrial gamma‐ray flash‐related lightning processes
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DOI：
10.1029/2009ja014835
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发表时间：
2010-06
影响因子：
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通讯作者：
X. Shao;T. Hamlin;David M. Smith
中科院分区：
文献类型：
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作者：
X. Shao;T. Hamlin;David M. Smith
[1] 本文详细比较了 RHESSI 卫星探测到的地面伽马射线闪光 (TGF) 与洛斯阿拉莫斯 Sferic 阵列 (LASA) 观测到的闪电过程。结果发现，所有 RHESI 检测到的 TGF 都与在云中向上传输电子的正常云内闪光有关。详细的时间比较表明，TGFs 更可能与小而不是大的闪电脉冲有关，当脉冲标准化为 100 km 的观测距离时，大部分在 10−1−100 V/m 的水平。如果假设放电是阶梯式引导过程中的各个步骤，则相应的峰值电流估计为 3-19 kA，其中大多数低于 10 kA。如果认为放电与电流传播速度为 c 的失控击穿过程直接相关，则峰值电流将为 0.4–3.2 kA。对 LASA 站附近事件的分析表明，TGF 最有可能在 IC 闪光的最初几毫秒内发生，同时放电从云中的负电荷区域垂直向上发展到正电荷区域。与TGF相关的闪电脉冲沿向上发展的高度估计在10.5-14.1公里范围内。在一次 TGF 后 2.9 ms 发现了峰值电流为 80 kA、高度为 16.1 km 的强 NBE，并且被认为与 TGF 没有直接关系，但可能是由 TGF 相关放电过程预先调节的。
[1] This paper presents detailed comparisons between terrestrial gamma-ray flashes (TGFs) detected by the RHESSI satellite and the lightning processes observed by the Los Alamos Sferic Array (LASA). It was found that all RHESSI-detected TGFs were related to normal intracloud flashes that transported electrons upward in the cloud. Detailed temporal comparisons suggest that TGFs are more likely related to small, rather than large, lightning pulses, mostly at the level of 10−1−100 V/m when the pulses are normalized to an observation distance of 100 km. The corresponding peak current was estimated to be 3–19 kA with most of them below 10 kA, if the discharges were assumed to be individual steps in a stepped-leader process. If the discharges were considered to be directly associated with runaway breakdown processes with a current propagation speed of c, the peak current would be 0.4–3.2 kA. Analysis of events that were close to the LASA stations showed that TGFs were most likely to occur during the initial milliseconds of IC flashes while the discharge developed vertically upward from the negative to the positive charge regions in the cloud. The heights of the TGF-related lightning pulses were estimated to be in the range of 10.5–14.1 km along the upward development. An intense NBE with a peak current of 80 kA and a height of 16.1 km was found 2.9 ms after one TGF, and is believed to not be directly associated with the TGF but may be preconditioned by the TGF-related discharge process.