DOI: 10.1002/jgrd.50512
论文题名: Competing and cutoff leaders before "upward illumination"-type lightning ground strokes
作者: Stolzenburg M. ; Marshall T.C. ; Karunarathne S. ; Karunarathna N. ; Warner T.A. ; Orville R.E.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 13 起始页码: 7182
结束页码: 7198
语种: 英语
英文关键词: high-speed video
; interstroke interval
; return stroke
; stepped leader
Scopus关键词: Lightning protection
; Video recording
; Frames per seconds
; Ground connections
; High-speed video
; interstroke interval
; Negative lightning
; Physical mechanism
; Return stroke
; Stepped leader
; High speed cameras
; data set
; lightning
; luminescence
; visible spectrum
英文摘要: High-speed video data provide evidence to examine a hypothesis regarding the physical mechanism resulting in the very weak "upward illumination" (UI) strokes occurring within a few milliseconds after a normal return stroke (RS) of a negative lightning flash. These short-duration (visible < 1 ms) strokes form a new ground connection, without apparent connection to the main RS, over their relatively short (< 3 km) visible upward return path. In a data set of 170 video flashes acquired in 2011 at 50,000 frames per second, there are 20 clear UI examples in 18 flashes at 2.5-32.3 km range from the camera. Average separation values are 1.25 ms and 1.9 km between ground connections of the UI stroke and main RS. In 15 cases, the data show a distinct stepped leader or branch to the UI which develops concurrently with the stepped leader to the main RS. The estimated altitude of the descending UI leader tip just before the main RS occurs ranges from 50 to 610 m, and in seven cases, stepping is visible in the UI leader after the main RS. In most examples, the RS and UI appear as separate channels for their entire visible portion, but in five cases, there is an obvious junction indicating the UI leader is a cutoff branch from the main leader. A generalized schematic of the seven main luminosity stages in a typical UI is described, accompanied by examples of each stage, to support the existence of competing and cutoff leader branches. Key Points High-speed video data show evidence of cut-off gaps in stepped leaders Stepping is visible at the lower end of cut-off leaders after the return stroke Competing, disconnected leader branches result in short UI-type strokes ©2013. American Geophysical Union. All Rights Reserved. 资助项目: AGS-1016004
; AGS-1110030
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63591
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Department of Physics and Astronomy, University of Mississippi, University, MS 38677-1848, United States; Department of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, SD, United States; Department of Atmospheric Sciences, Texas AandM University, College Station, TX, United States
Recommended Citation:
Stolzenburg M.,Marshall T.C.,Karunarathne S.,et al. Competing and cutoff leaders before "upward illumination"-type lightning ground strokes[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(13)