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| Publications [#283035] of Steven A. Cummer
Papers Published
- Marshall, T; Stolzenburg, M; Karunarathne, S; Cummer, S; Lu, G; Betz, HD; Briggs, M; Connaughton, V; Xiong, S, Initial breakdown pulses in intracloud lightning flashes and their relation to terrestrial gamma ray flashes,
Journal of Geophysical Research Atmospheres, vol. 118 no. 19
(October, 2013),
pp. 10-925, American Geophysical Union (AGU), ISSN 0148-0227 [doi]
(last updated on 2023/06/01)
Abstract:
The initial breakdown stage of 10 intracloud lightning flashes that may have produced terrestrial gamma ray flashes (TGFs) is studied with wideband E-change, multiband B-change, and VHF lightning mapping data; these flashes fit published criteria known to be associated with TGFs. The (x, y, z, t) locations of fast initial breakdown pulses (IBPs) were determined with E-change data using a time-of-arrival (TOA) technique. Each IBP includes one or more fast-rising subpulses. Previous research has shown that a typical intracloud flash initiates just above the main negative cloud charge (MNCC), then an initial negative leader propagates upward in 1-20 ms to the bottom of the upper positive cloud charge (UPCC), thereby establishing a conducting path between the MNCC and UPCC. TOA locations indicate that IBPs are directly related to the initial negative leader. The IBPs primarily occur in short (<750 μs) bursts of two to five pulses, and each burst produces a slow, monotonic E-change. Typically, one to three IBP bursts are needed to span the vertical gap from the MNCC to the UPCC, with successive bursts separated by 1-5 ms. In the B-change data, each IBP burst has an associated ULF pulse and several LF pulses, and these are caused by the same physical events that produce the slow, monotonic E-change and fast-rising IBP subpulses, respectively. Based on similarities with known TGF-associated signals, we speculate that a relativistic electron avalanche causes each LF pulse/IBP subpulse pair; thus, each pair has the potential to cause a TGF. Key Points Initial breakdown pulses (IBPs) of IC flashes move upward as the initial leader Initial leaders develop with a few IBP bursts separated by a few milliseconds IBPs and slow E-changes are causally connected to LF and slow ULF pulses of TGFs ©2013. American Geophysical Union. All Rights Reserved.
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