On the relationship between continuing current and positive leader growth

Lapierre, Jeff; Sonnenfeld, R.; Edens, H. E.; Stock, Michael

doi:10.1002/2014jd022080

Cited by 21 publications

(40 citation statements)

References 21 publications

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“…The flash that we study occurred on 8 July 2013 at 20:28:56 UTC (Figure 10 of Lapierre et al [] and Figures and of the present study). This flash produced seven strokes along two channels to ground, as evidenced by the occurrence of two stepped leaders seen in Figure (highlighted in green before events 1 and 3).…”

Section: Analysis and Discussionsupporting

confidence: 91%

“…The NLDN data (colored triangles in a and vertical lines in b) detected a strong, +94 kA +CG 125 ms into the flash (event 2 in ). The occurrence of the +CG stroke was confirmed by the LEFA data (b, middle), whose monopolar field change following the stroke at the multiple LEFA stations (see Figure ) [ Lapierre et al , ] indicated a +CC of about 70 ms duration (gray shaded area). Typical of +CGs, the leader to ground was not detected by the LMA, due to being weakly radiating and masked by the ongoing negative breakdown in the storm.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…These short‐duration growth rate spikes do not appear to be associated with CC growth and are therefore not discussed further. Overall, these results agree with the results from Lapierre et al [] and help confirm that −CC does not affect the growth rate of the in‐cloud positive leader.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…This allows us to measure the growth rate throughout the flash (see Figure ). For more details on this analysis, see Lapierre et al [].…”

Section: Instrumentation and Methodsmentioning

confidence: 99%

“…In a previous study [ Lapierre et al , ], we showed that one cannot tell if or when −CGs produce a CC based on VHF lightning mapping observations of the positive in‐cloud breakdown. This was documented by quantitatively evaluating the growth rate of the positive breakdown versus time during several multistroke −CG flashes, as determined from detailed observations with the Langmuir 3‐D Lightning Mapping Array (LMA).…”

Section: Introductionmentioning

confidence: 99%

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Expanding on the relationship between continuing current and in‐cloud leader growth

et al. 2017

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When lightning connects to the ground, there is a large surge of current, called the return stroke, which is occasionally followed by a longer‐lasting steady current, called continuing current (CC). In a previous study of negative cloud‐to‐ground (−CG) flashes, we observed the growth rate of in‐cloud positive leaders in an attempt to identify occurrences of CC. However, there was no observed change in positive leader growth rate during CC of negative CG flashes. In this study, we use the Langmuir Electric Field Array, Lightning Mapping Array, and Flash‐Continuous Broadband Digital Interferometer data to extend the previous study to the growth of the negative leader during positive CG flashes. We have found that in contrast with previous results, negative leader growth during positive CG flashes does show increases in growth rates coincident with CC. Finally, we find that the growth rate magnitudes for positive and negative leaders are typically ∼2–4 km/10 ms and ∼25–40 km/10 ms, respectively. These contrasting results highlight the differences between positive and negative leaders and provide strong evidence as to why −CC and +CC behave differently. Negative leaders inject higher amounts of current and allow the channel to remain conductive throughout the duration of CC. Whereas for positive leaders, the channel becomes nonconductive relatively quickly. It is therefore disconnected from the channel to the ground, and, due to the positive leader's continued growth, an electric potential is built up until a K event is produced that re‐ionizes the channel.

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Section: Analysis and Discussionsupporting

confidence: 91%

Section: Analysis and Discussionmentioning

confidence: 99%

Section: Analysis and Discussionmentioning

confidence: 99%

“…This allows us to measure the growth rate throughout the flash (see Figure ). For more details on this analysis, see Lapierre et al [].…”

Section: Instrumentation and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Expanding on the relationship between continuing current and in‐cloud leader growth

et al. 2017

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Characteristics of lightning leader propagation and ground attachment

et al. 2015

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The grounding process and the associated leader behavior were analyzed by using high‐speed video record and time‐correlated electric field change for 37 natural negative cloud‐to‐ground flashes. Weak luminous grounded channel was recognized below the downward leader tip in the frame preceding the return stroke, which is inferred as upward connecting leader considering the physical process of lightning attachment, though not directly confirmed by sequential frames. For stepped leader‐first return strokes, the upward connecting leaders tend to be induced by those downward leader branches with brighter luminosity and lower channel tip above ground, and they may accomplish the attachment with great possibility. The upward connecting leaders for 2 out of 61 leader‐subsequent stroke sequences were captured in the frame prior to the return stroke, exhibiting relatively long channel lengths of 340 m and 105 m, respectively. The inducing downward subsequent leaders were of the chaotic type characterized by irregular electric field pulse train with duration of 0.2–0.3 ms. The transient drop of the high potential difference between stepped leader system and ground when the attachment occurred would macroscopically terminate the propagation of those ungrounded branches while would not effectively prevent the development of the existing space stem systems in the low‐conductivity streamer zone apart from the leader tip. When the ungrounded branches are of poor connection with the main stroke channel, their further propagation toward ground would be feasible. These two factors may contribute to the occurrence of multiple grounding within the same leader‐return stroke sequence.

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Global distribution and properties of continuing current in lightning

Bitzer

2017

JGR Atmospheres

102

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Continuing current is a process in lightning in which the current in a conducting channel can flow for much longer than in a typical lightning discharge. The phenomenon can be characterized by the continuous optical emission that accompanies the current flow. Using the Lightning Imaging Sensor (LIS), lightning with continuing current is identified on a global scale. Lightning that contains optical emission over at least five consecutive LIS frames, roughly 7–9 ms, are classified as continuing current flashes. This differs from typical lightning discharges that produce optical emission for one or two consecutive frames. Of the flashes detected by LIS, 11.2% contain continuing current. These flashes optically radiate over a larger footprint and have a longer duration than ones that do not. The spatial distribution of these flashes indicates that regions of high lightning activity may not be correlated with a high likelihood of continuing current flashes. Further, oceanic and winter lightning are shown to have a higher proportion of continuing current flashes. Finally, 25–40% of flashes identified by LIS to have continuing current have only an intracloud pulse detected by the National Lightning Detection Network (NLDN), with no cloud‐to‐ground strokes detected.

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On the relationship between continuing current and positive leader growth

Cited by 21 publications

References 21 publications

Expanding on the relationship between continuing current and in‐cloud leader growth

Expanding on the relationship between continuing current and in‐cloud leader growth

Characteristics of lightning leader propagation and ground attachment

Global distribution and properties of continuing current in lightning

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