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A Comparison on the E‐Change Pulses Occurring in the Bi‐Level Polarity‐Opposite Charge Regions of the Intracloud Lightning Flashes
Author(s) -
Shi Dongdong,
Wang Daohong,
Wu Ting,
Takagi Nobuyuki
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd032996
Subject(s) - pulse (music) , amplitude , flash (photography) , lightning (connector) , physics , train , pulse amplitude modulation , channel (broadcasting) , optics , telecommunications , computer science , geography , power (physics) , cartography , quantum mechanics , detector
We have compared the E‐change pulses occurring in the upper positive charge region (UPCR) and the middle negative charge region (MNCR) of 41 normal intracloud (IC) flashes. E‐change pulses can be roughly grouped into isolated pulses and pulse trains with both positive and negative polarities. Although isolated pulses occurred about equally in UPCR and MNCR, there were much more pulse trains in MNCR than UPCR. Overall, the average amplitude, rise time, half‐peak width, and fall time of isolated pulses (pulse trains) are 56% larger (115% larger), 31% faster (43% slower), 25% narrower (46% wider), and 26% shorter (62% longer) in UPCR than in MNCR. Interestingly, in the same charge region, positive and negative pulses share similar characteristics. Based on a typical well‐structured IC, it was found that the majority of isolated pulses in both UPCR and MNCR occurred at or close to the leader tips. In contrast, about 30% UPCR pulse trains occurred at or close to the tip, while the remaining 70% pulse trains occurred in the leader channel retracing along the leader channel away from the flash origin; for MNCR pulse trains, about 60% occurred close to the tip, and 40% occurred in the channel with a backward extension to the flash origin. Based on these characteristics, we have discussed the physical nature of various types of pulses and pointed out that a leader is likely to progress with a fluctuating behavior when it is neutralizing space charge distributed in a region with sufficient thickness and width.