气候变化领域集成服务门户(CCPortal): On the Transition From Initial Leader to Stepped Leader in Negative Cloud-to-Ground Lightning

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DOI	10.1029/2019JD031765
	On the Transition From Initial Leader to Stepped Leader in Negative Cloud-to-Ground Lightning
	Stolzenburg M.; Marshall T.C.; Karunarathne S.
发表日期	2020
ISSN	2169897X
卷号	125 期号:4
英文摘要	High-speed video and electric field change data are used to describe the first 5 ms of a negative cloud-to-ground flash. These observations reveal an evolution in character of the luminosity and electric field change pulses as two branches of the leader separately transition from initial leader to propagating as a negative stepped leader (SL). For the first time reported, there is evidence of weak luminosity coincident with the initiating event, a weak bipolar pulse 60 μs prior to the first initial breakdown (IB) pulse. During the IB stage, the initial leader advances intermittently at intervals of 100–280 μs, in separate light bursts that are bright for a few 20-μs frames and are time coincident with IB pulses. In the intervals between IB pulses, the initial leader is dim or invisible during the earliest 1.8 ms. Within 2 ms, the leader propagation begins transitioning to an early SL phase, in which the leader tip advances at more regular intervals of 40–80 μs during relatively dim and brief steps which are coincident with SL pulses having short duration, small amplitude, and typically unipolar waveform. These data indicate that when the entire initial leader length behind the lower end begins to remain illuminated between bursts, the propagation mode changes from IB bursts to SL steps, and the IB stage ends. The results support a hypothesis that the early initial leader development occurs in the absence of a continuously hot channel, thus the initial leader propagation is physically unlike the self-propagating SL advance. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	high-speed video; initial breakdown; initial leader; lightning initiation; stepped leader
语种	英语
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186167
作者单位	Department of Physics and Astronomy, University of MississippiMS, United States; Department of Physics, Baptist College of Health Sciences, Memphis, TN, United States
推荐引用方式 GB/T 7714	Stolzenburg M.,Marshall T.C.,Karunarathne S.. On the Transition From Initial Leader to Stepped Leader in Negative Cloud-to-Ground Lightning[J],2020,125(4).
APA	Stolzenburg M.,Marshall T.C.,&Karunarathne S..(2020).On the Transition From Initial Leader to Stepped Leader in Negative Cloud-to-Ground Lightning.Journal of Geophysical Research: Atmospheres,125(4).
MLA	Stolzenburg M.,et al."On the Transition From Initial Leader to Stepped Leader in Negative Cloud-to-Ground Lightning".Journal of Geophysical Research: Atmospheres 125.4(2020).