What occurs in K process of cloud flashes?

Akita, Manabu; Nakamura, Yoshitaka; Yoshida, Shigeaki; Morimoto, Takeshi; Ushio, Tomoo; Kawasaki, Zen; Wang, Daohong

doi:10.1029/2009jd012016

Cited by 51 publications

(48 citation statements)

References 19 publications

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“…Lightning sources of these impulsive emissions can be located via measurements at multiple ground‐based receivers using the “time‐of‐arrival” technique [ Proctor , ], such as the Lightning Mapping Array (LMA) developed by New Mexico Tech [ Rison et al ., 1999; Thomas et al ., ]. Positive leaders through negatively charged cloud regions are less impulsive, while their trails can be resolved by detecting associated retrograde negative breakdown (so‐called “recoil leaders” or K processes) when they encounter localized negative charge concentrations [ Thomas et al ., ; Akita et al ., ]. Therefore, the LMA‐resolved lightning structure provides an alternative way to construct the gross charge structure of thunderclouds in addition to balloon soundings of electric field profile [ Winn et al ., ; Stolzenburg et al ., ; Coleman et al ., ; Carey et al ., ; Rust et al ., ; Bruning et al ., ].…”

Section: Instrumentation Network and Methodsmentioning

confidence: 99%

Coordinated observations of sprites and in‐cloud lightning flash structure

Cummer

et al. 2013

JGR Atmospheres

159

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[1] The temporal and spatial development of sprite-producing lightning flashes is examined with coordinated observations over an asymmetric mesoscale convective system (MCS) on 29 June 2011 near the Oklahoma Lightning Mapping Array (LMA). Sprites produced by a total of 26 lightning flashes were observed simultaneously on video from Bennett, Colorado and Hawley, Texas, enabling a triangulation of sprites in comparison with temporal development of parent lightning (in particular, negatively charged stepped leaders) in three-dimensional space. In general, prompt sprites produced within 20 ms after the causative stroke are less horizontally displaced (typically <30 km) from the ground stroke than delayed sprites, which usually occur over 40 ms after the stroke with significant lateral offsets (>30 km). However, both prompt and delayed sprites are usually centered within 30 km of the geometric center of relevant LMA sources (with affinity to negative stepped leaders) during the prior 100 ms interval. Multiple sprites appearing as dancing/jumping events associated with a single lightning flash could be produced either by distinct strokes of the flash, by a single stroke through a series of current surges superposed on an intense continuing current, or by both. Our observations imply that sprites elongated in one direction are sometimes linked to in-cloud leader structure with the same elongation, and sprites that were more symmetric were produced above the progression of multiple negative leaders. This suggests that the large-scale structure of sprites could be affected by the in-cloud geometry of positive charge removal. Based on an expanded dataset of 39 sprite-parent flashes by including more sprites recorded by one single camera over the same MCS, the altitude (above mean sea level, MSL) of positively charged cloud region tapped by sprite-producing strokes declined gradually from~10 km MSL (À35 C) to around 6 km MSL (À10 C) as the MCS evolved through the mature stage. On average, the positive charge removal by causative strokes of sprites observed on 29 June is centered at 3.6 km above the freezing level or at 7.9 km above ground level.

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Section: Instrumentation Network and Methodsmentioning

confidence: 99%

Coordinated observations of sprites and in‐cloud lightning flash structure

Cummer

et al. 2013

JGR Atmospheres

159

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“…After leaders stop propagating, there are repeated jumps of the electric field at the ground (and aloft), called K changes [ Ogawa and Brook , 1964], which are produced by propagating discharges similar to dart leaders in that they carry negative charge along a channel previously ionized by a negative leader in the same direction as the negative leader [ Ogawa and Brook , 1964; Shao et al , 1995; Mazur , 2002; Akita et al , 2010]. The discharges that produce K changes have been have given many names.…”

Section: Introductionmentioning

confidence: 99%

Lightning leader stepping, K changes, and other observations near an intracloud flash

et al. 2011

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[1] An intracloud lightning flash in central New Mexico began with the initiation of a negative stepped leader at an altitude of 8.2 km above sea level. As this leader propagated eastward and upward, at 9.1 km above sea level it passed about 200 m to the north of a balloon-borne, electric field-change instrument (Esonde). After the first leader stopped, a second negative stepped leader began near the point of origin of the first leader, but it propagated away from the Esonde. From the changes in the electric vectors and the locations of impulsive radio frequency sources detected by a lightning-mapping array (LMA), we conclude the following: (1) The first negative stepped leader was not preceded by any significant charge rearrangement due to positive leaders. (2) Each step of the first negative leader had both a forward-going wave and a step recoil wave that propagated simultaneously backwards away from the leader tip along the existing channel. The presence of a step recoil wave during each step leads to an explanation for the existence of stepping. (3) After the first (nearby) leader stopped, step recoil waves from the second (distant) leader may have found their way onto the channel formed by the first leader. (4) After the second leader stopped, waves carrying negative charge propagated along the channel of the first leader, producing strong K changes in the electric field at the Esonde and providing a good record of the wavefront shapes.

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“…A summary of research on pulses and currents in lightning flashes can be found in the book by Rakov and Uman [2003, chapters 4 and 7]. For more recent results and reviews on triggered flashes and flashes to towers see the articles by Rakov et al [2003], Miki et al [2005], Campos et al [2007], Flache et al [2008], Campos et al [2009], Akita et al [2010], and Qie et al [2011].…”

Section: Introductionmentioning

confidence: 99%

Luminous pulses during triggered lightning

et al. 2012

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[1] A triggered lightning flash that transferred negative charge to ground in central New Mexico produced more than three levels of branching above the main channel to ground in a 1 km vertical field of view. A high-speed video recording shows that the main channel had about 50 brief luminous pulses, many of which were superimposed on a slowly changing persistent luminosity. In contrast, superposition was rare in the uppermost visible branches because luminous pulses first appeared on preexisting dark channels before merging into a luminous channel. This observation suggests that luminous pulses in triggered and natural lightning originate only on dark branches and that the complexity of the main channel to ground is the result of multiple mergers of dark branches with pulses into luminous branches without pulses. This suggestion is contrary to an earlier conclusion that there are two kinds of luminous pulses. We also observe behavior characteristic of electromagnetic waves on transmission lines: when a downward propagating luminous pulse reaches a junction with another initially dark branch, it travels both upward and downward along that branch. Upon reaching the ground the downward propagating wave produces a bright reflection which also splits at the junctions, producing luminosity for a short distance upward in one direction while propagating much farther upward along the path charged by the downward propagating wave. However, when a downward moving luminous pulse reaches a junction with an initially luminous branch, splitting is not evident, probably due to the greater conductivity of the luminous channel.

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What occurs in K process of cloud flashes?

Cited by 51 publications

References 19 publications

Coordinated observations of sprites and in‐cloud lightning flash structure

Coordinated observations of sprites and in‐cloud lightning flash structure

Lightning leader stepping, K changes, and other observations near an intracloud flash

Luminous pulses during triggered lightning

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