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

Zhou, Mi; Wang, D.; Wang, J.; Takagi, Nobuyuki; Gamerota, W. R.; Uman, M. A.; Jordan, D. M.; Pilkey, J. T.; Ngin, T.

doi:10.1002/2014jd022367

Cited by 37 publications

(32 citation statements)

References 26 publications

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“…In Figure , ℓ R also appears to fit a quadratic in I p slightly better than ℓ o fits a quadratic, and similar trends been reported by Zhou et al . [] during the “initial rising stage” of a RS, i.e., during the fast rise to peak (for many of the same events) and by Carvalho et al . [] for the bottom of the channel in RTL.…”

Section: Discussionmentioning

confidence: 99%

Optical power and energy radiated by return strokes in rocket‐triggered lightning

Quick

Krider

2017

JGR Atmospheres

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The broadband optical radiation covering the visible and near‐infrared (VNIR) spectral regions (0.4–1.0 μm) has been measured from 70 negative return strokes (RS) in rocket‐triggered lightning; 17 events were recorded in 2011, and 53 were recorded in 2012. The radiometers were calibrated, and all measurements were time‐correlated with currents measured at the channel base. The risetime and peak of an irradiance waveform are determined primarily by the RS current and by the geometrical growth and total length of channel that is in the field of view of the sensor. Following an initial peak, the irradiance decays faster than the current until there is a plateau or secondary maximum 20 to 40 μs (median of 22 μs) after the peak current, a time when the current itself is steadily decreasing. Estimates of the space‐ and time‐average optical power per unit length (ℓo) that is emitted at the source during onset of RS have been computed using the measured slopes of 70 irradiance waveforms together with an assumption that the initial speed of propagation is 1.2 × 108 m/s. The values range from 0.25 to 9.5 MW/m, with a mean and standard deviation of 2.4 ± 1.7 MW/m, and they are in good agreement with prior estimates of ℓo that were made by Quick and Krider (2013) for the subsequent return strokes in natural lightning that reilluminate a preexisting channel. The values of ℓo also agree with numerical estimates of the VNIR power per unit length that were computed by Paxton et al. (1986). Estimates of the peak optical power per unit length (ℓR) that is radiated at the source have been derived from the peaks of 53 irradiance waveforms, and the values range from 0.4 to 11 MW/m with a mean and standard deviation of 4.2 ± 2.5 MW/m. Both ℓo and ℓR are approximately proportional to the square of the peak current at the channel base. Estimates of the total optical energy per unit length, Jo, that is radiated in the VNIR have been computed by integrating the irradiance waveforms over 2 ms. The values of Jo have a mean and standard deviation of 150 ± 140 J/m, and they are proportional to the total charge that is transported to ground in that interval.

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Section: Discussionmentioning

confidence: 99%

Optical power and energy radiated by return strokes in rocket‐triggered lightning

Quick

Krider

2017

JGR Atmospheres

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“…Zhou et al [] reported that M‐component and initial continuous current (ICC) pulses in triggered lightning having risetimes in the range of 10 µs to 100 µs for both current and luminosity at the ground exhibited a current‐to‐luminosity delay on the order of the current and luminosity risetimes. Thus, from Carvalho et al [] and Zhou et al [], it would appear that the observed delay between current and luminosity at the ground increases with both increasing current risetime and increasing luminosity risetime.…”

Section: Introductionmentioning

confidence: 99%

Lightning current and luminosity at and above channel bottom for return strokes and M‐components

Carvalho

Uman

Jordan

et al. 2015

J. Geophys. Res. Atmos.

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We measured current and luminosity at the channel bottom of 12 triggered lightning discharges including 44 return strokes, 23 M‐components, and 1 initial continuous current pulse. Combined current and luminosity data for impulse currents span a 10–90% risetime range from 0.15 to 192 µs. Current risetime and luminosity risetime at the channel bottom are roughly linearly correlated (τr,I = 0.71τr,L1.08). We observed a time delay between current and the resultant luminosity at the channel bottom, both measured at 20% of peak amplitude, that is approximately linearly related to both the luminosity 10–90% risetime (Δt20,b = 0.24τr,L1.12) and the current 10–90% risetime (Δt20,b = 0.35τr,I1.03). At the channel bottom, the peak current is roughly proportional to the square root of the peak luminosity (IP = 21.89LP0.57) over the full range of current and luminosity risetimes. For two return strokes we provide measurements of stroke luminosity vs. time for 11 increasing heights to 115 m altitude. We assume that measurements above the channel bottom behave similarly to those at the bottom and find that (1) one return stroke current peak decayed at 115 m to about 47% of its peak value at channel bottom, while the luminosity peak at 115 m decayed to about 20%, and for the second stroke 38% and 12%, respectively; and (2) measured upward return stroke luminosity speeds of the two strokes of 1.10 × 108 and 9.7 × 107 ms−1 correspond to current speeds about 30% faster. These results represent the first determination of return stroke current speed and current peak value above ground derived from measured return stroke luminosity data.

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“…And also the longer the channel segment viewed by the sensor, the wider the light waveform it detected. These results can well explain those observed light waveforms of return strokes in literature [ Wang et al ., ; Zhou et al ., ].…”

Section: Modeling Resultsmentioning

confidence: 99%

“…[] and Zhou et al . [] compared the current and optical signal with a high speed detection system for triggered lightning discharges. They found that the rising front of the current is always faster than that of the optical signal, which are well consistent with our simulation results.…”

Section: Modeling Resultsmentioning

confidence: 99%

A leader‐return‐stroke consistent macroscopic model for calculations of return stroke current and its optical and electromagnetic emissions

Cai

Chen

et al. 2017

JGR Atmospheres

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A downward lightning flash usually starts with a downward leader and an upward connecting leader followed by an upward return stroke. It is the preceding leader that governs the following return stroke property. Besides, the return stroke property evolves with height and time. These two aspects, however, are not well addressed in most existing return stroke models. In this paper, we present a leader‐return stroke consistent model based on the time domain electric field integral equation, which is a growth and modification of Kumar's macroscopic model. The model is further extended to simulate the optical and electromagnetic emissions of a return stroke by introducing a set of equations relating the return stroke current and conductance to the optical and electromagnetic emissions. With a presumed leader initiation potential, the model can then simulate the temporal and spatial evolution of the current, charge transfer, channel size, and conductance of the return stroke, furthermore the optical and electromagnetic emissions. The model is tested with different leader initiation potentials ranging from −10 to −140 MV, resulting in different return stroke current peaks ranging from 2.6 to 209 kA with different return stroke speed peaks ranging from 0.2 to 0.8 speed of light and different optical power peaks ranging from 4.76 to 248 MW/m. The larger of the leader initiation potential, the larger of the return stroke current and speed. Both the return stroke current and speed attenuate exponentially as it propagates upward. All these results are qualitatively consistent with those reported in the literature.

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

Cited by 37 publications

References 26 publications

Optical power and energy radiated by return strokes in rocket‐triggered lightning

Optical power and energy radiated by return strokes in rocket‐triggered lightning

Lightning current and luminosity at and above channel bottom for return strokes and M‐components

A leader‐return‐stroke consistent macroscopic model for calculations of return stroke current and its optical and electromagnetic emissions

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