A high speed optical imaging system for studying lightning attachment process

Wang, Daohong; Watanabe, Teiji; Takagi, Nobuyuki

doi:10.1109/apl.2011.6111050

Cited by 23 publications

(22 citation statements)

References 8 publications

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“…For this study, only data from LAPOS2 and LAPOS3 are used. As reported previously by Wang et al [, ], LAPOS employs a type of photodiode‐fiber optics array system with LAPOS2 having a sampling rate of 10 MS/s and LAPOS3 having a sampling rate of either 10 MS/s or 100 MS/s for different lightning channel sections. For this study, LAPOS 2 and LAPOS 3 were installed in a so‐called optical building about 200 m away from the rocket launcher used for triggering lightning from natural thunderstorms using the rocket and wire technique.…”

Section: Methodsmentioning

confidence: 99%

Luminosity progression in dart‐stepped leader step formation

et al. 2016

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Using a high‐speed optical imaging system, we have observed the step formation bright pulse discharges occurring at the tip of dart‐stepped leaders of rocket triggered lightning with a time resolution of 0.1 µs and a spatial resolution of about 1.4 m. Each of the step formation pulse discharges appeared to initiate at a location immediately below the bottom of its previous pulse discharge and to propagate in bidirectional (upward and downward) waves with a speed on the order of 107 m/s. The downward waves of the pulse discharges tended to slow down significantly after they propagated a distance of about 2 m. Based on the results observed in this study and those published in literatures, we propose a conceptual view of leader step formation.

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Section: Methodsmentioning

confidence: 99%

Luminosity progression in dart‐stepped leader step formation

et al. 2016

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“…As reported previously by Wang et al . [, , ], LAPOS employs a type of photodiode‐fiber optics array system specifically designed for observing the lightning attachment process. One major advantage of the system is that it has a wide horizontal view, about 5–10 times larger than its vertical view.…”

Section: Observations and Datamentioning

confidence: 99%

Lightning attachment processes of three natural lightning discharges

Wang

Takagi

Gamerota

et al. 2015

J. Geophys. Res. Atmos.

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Using a high-speed optical imaging system specifically designed for observing the lightning attachment process, we have documented the attachment process for six strokes in three natural lightning flashes. All strokes initiate at a height above ground and propagate bidirectionally from that height, similar to the return strokes of artificially initiated (triggered) lightning previously reported by Wang et al. (2013Wang et al. ( , 2014. Though the data are quite limited, these natural return strokes suggest a correlation between larger peak current and greater initiation height. Initiation heights determined here span 12-60 m with a typical uncertainty of less than 10 m. The initial upward return stroke luminosity speeds range from (0.8 ± 0.2) to (2.0 ± 0.4) × 10 8 m/s. Two first return strokes downward luminosity speeds are assessed as (1.6 ± 0.3) × 10 7 m/s and (1.4 ± 0.3) × 10 8 m/s. One of the first return strokes appeared to be initiated with a stepping pulse discharge of its leader as an inseparable part of the return stroke.

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“…The photodiodes used for the sensitive channels are C5460 avalanche photodiode modules and for the insensitive channels are S3399 PIN photodiodes, both coupled with amplifiers made by Hamamatsu Photonics. Both sensitive and insensitive photodiode systems have similar spectral response centered at 800 nm [ Wang et al ., ]. S3 has an upper frequency response of 10 MHz limited by the C5460 module, and S4 has an upper frequency response of 20 MHz limited by the oscilloscope digitizer input [ Wang et al ., ].…”

Section: Experiments and Data Overviewmentioning

confidence: 99%

Correlation between the channel‐bottom light intensity and channel‐base current of a rocket‐triggered lightning flash

Zhou

Wang

et al. 2014

JGR Atmospheres

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The correlations between channel-bottom light intensity and channel-base current of all discharge processes of a rocket-and-wire-triggered lightning flash, including initial continuous current (ICC) pulses, ICC pulse background continuing current (IBCC), return strokes, M components, and M component background continuing currents (MBCC), have been investigated. A rough linear correlation has been found between the current squared and the light intensity for ICC pulses (including peaks of different ICC pulses), IBCC, the initial rising stage (IRS) of return strokes (including current peaks of different strokes), and MBCC. The slopes of the correlation regression lines for the current squared versus light intensity of ICC pulses and IBCC are similar, but they are about 2-3 times smaller than the slopes of MBCC and 5-7 times smaller than the slopes of the IRS of return strokes. In contrast, a rough linear correlation has been found between the current and the light intensity for the later slow decay stage of return strokes and for the M components. The slopes of the correlation regression lines of the current versus the light intensity for these latter two processes are found to be similar. No simple correlation has been found between the current and the light intensity for the initial fast decay stage (IFDS) of return strokes. The duration of the IFDS of return strokes generally lasts from several microseconds to several tens of microseconds and is more or less directly proportional to the corresponding peak return stroke current squared. A time delay ranging from 12 μs to 300 μs has been found between the current and the light intensity of all ICC pulses and M components. The time delay decreases as the corresponding peak current increases.

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A high speed optical imaging system for studying lightning attachment process

Cited by 23 publications

References 8 publications

Luminosity progression in dart‐stepped leader step formation

Luminosity progression in dart‐stepped leader step formation

Lightning attachment processes of three natural lightning discharges

Correlation between the channel‐bottom light intensity and channel‐base current of a rocket‐triggered lightning flash

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