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Title:Observations of the origin of downward terrestrial gamma-ray flashes
Authors:ID Belz, J. W. (Author)
ID Krehbiel, P. R. (Author)
ID Remington, J. (Author)
ID Stanley, M. A. (Author)
ID Abbasi, R. U. (Author)
ID LeVon, R. (Author)
ID Rison, W. (Author)
ID Rodeheffer, D. (Author)
ID Abu-Zayyad, T. (Author)
ID Lundquist, Jon Paul (Author)
Work type:Unknown
Typology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
Abstract:In this paper we report the first close, high‐resolution observations of downward‐directed terrestrial gamma‐ray flashes (TGFs) detected by the large‐area Telescope Array cosmic ray observatory, obtained in conjunction with broadband VHF interferometer and fast electric field change measurements of the parent discharge. The results show that the TGFs occur during strong initial breakdown pulses (IBPs) in the first few milliseconds of negative cloud‐to‐ground and low‐altitude intracloud flashes and that the IBPs are produced by a newly identified streamer‐based discharge process called fast negative breakdown. The observations indicate the relativistic runaway electron avalanches (RREAs) responsible for producing the TGFs are initiated by embedded spark‐like transient conducting events (TCEs) within the fast streamer system and potentially also by individual fast streamers themselves. The TCEs are inferred to be the cause of impulsive sub‐pulses that are characteristic features of classic IBP sferics. Additional development of the avalanches would be facilitated by the enhanced electric field ahead of the advancing front of the fast negative breakdown. In addition to showing the nature of IBPs and their enigmatic sub‐pulses, the observations also provide a possible explanation for the unsolved question of how the streamer to leader transition occurs during the initial negative breakdown, namely, as a result of strong currents flowing in the final stage of successive IBPs, extending backward through both the IBP itself and the negative streamer breakdown preceding the IBP.
Keywords:terrestrial gamma-ray flashes, lightning, fast breakdown, initial breakdown pulse, atmospheric electricity, transient conducting events
Year of publishing:2020
Number of pages:str. 1-36
Numbering:Vol. 125, no. 23
PID:20.500.12556/RUNG-6245 New window
COBISS.SI-ID:50284291 New window
ISSN on article:2169-8996
DOI:10.1029/2019JD031940 New window
Publication date in RUNG:04.02.2021
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Record is a part of a journal

Title:Journal of geophysical research
Shortened title:J. geophys. res., Atmos.
Publisher:John Wiley & Sons
COBISS.SI-ID:310441 New window