Characterization of initial current pulses in negative rocket‐triggered lightning with sensitive magnetic sensor

Lu, Gaopeng; Zhang, Hongbo; Jiang, Rubin; Fan, Yanfeng; Qie, Xiushu; Liu, Mingyuan; Sun, Zhongchang; Wang, Zhichao; Tian, Ye; Liu, Kun

doi:10.1002/2016rs005945

Cited by 23 publications

(53 citation statements)

References 41 publications

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“…The current pulse is unipolar during the initial stage of Tr_201705, which is similar to the measurement of Jiang et al (2013). The radiation from the precursor current pulses is readily observed in the measurements of ΔE and B-field, both having relatively high signal-to-noise ratio to detect weak current pulses with magnitude as low as a few hundred milliamperes (Lu et al, 2016). The magnetic .…”

Section: Measurement and Datasupporting

confidence: 54%

“…As shown in Figure a, in the first 300‐μs time interval dominated by impulsive pulses, the half‐peak width of impulsive magnetic pulses is as short as 2 μs and typically less than 3 μs; for the subsequent time interval of about 600 μs dominated by ripple pulses (Figure b) with reduced amplitude and longer timescale (typically more than 5 μs), the half‐peak width can only be roughly estimated because of the partial overlapping of each other. The statistical analysis on the recurrence rate and interpulse interval of impulsive pulses and ripple pulses indicate that they involve the similar formation mechanism (Lu et al, ). However, the ripple pulses with smaller amplitude following the impulsive pulses are produced due to the low‐pass filtering effect of the prolonging leader with high impedance when the current pulses initiate at the tip of upward‐propagating leader and propagate downward along the leader channel (Fan et al, ).…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…The current pulse is unipolar during the initial stage of Tr_201705, which is similar to the measurement of Jiang et al (). The radiation from the precursor current pulses is readily observed in the measurements of Δ E and B ‐field, both having relatively high signal‐to‐noise ratio to detect weak current pulses with magnitude as low as a few hundred milliamperes (Lu et al, ). The magnetic pulses of the precursor measured at close distance are typically unipolar, and the sequence of magnetic pulses following the inception of a sustained upward positive leader contains 11 impulsive pulses and a longer sequence of ripple pulses lasting longer than 600 μs.…”

Section: Measurement and Datamentioning

confidence: 99%

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Underground Measurement of Magnetic Field Pulses During the Early Stage of Rocket‐Triggered Lightning

Fan

et al. 2019

JGR Atmospheres

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We examined the underground magnetic field near the lightning channel with low‐frequency magnetic sensor based on SHAndong Triggering Lightning Experiment (SHATLE). Two sensors were deployed, one at 1‐m height above ground and another one at 2‐m depth underground at a distance of 78 m from the lightning channel, and the magnetic pulses during the initial stage of triggered lightning were recorded. The experimental results show that the microsecond‐scale magnetic pulses radiated by the upward lightning leader can be detected in the subsurface space and the magnetic signal is modified by the soil medium. Specifically, the amplitude at the depth of 2 m is attenuated typically more than 55%, and the attenuation decreases as the timescale of the magnetic pulse increases; meanwhile, the peak time of the underground magnetic pulse is delayed by about 0.6 μs, and the half‐peak width of the magnetic pulse is increased by 0.2–0.8 μs (namely, by 20% to 32%). The results of Fourier analysis indicate that the component with relatively high frequency is subject to more attenuation than is the component with relatively low frequency. In addition, the simulation of magnetic field with the channel‐base current by using the transmission line model is consistent with the measurement, indicating that the modification on the waveform characteristics of the lightning pulse measured underground could provide valuable information for retrieving the electromagnetic parameters of soil.

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Section: Measurement and Datasupporting

confidence: 54%

Section: Analysis and Resultsmentioning

confidence: 99%

Section: Measurement and Datamentioning

confidence: 99%

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Underground Measurement of Magnetic Field Pulses During the Early Stage of Rocket‐Triggered Lightning

Fan

et al. 2019

JGR Atmospheres

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“…For example, in quite humid air, it propagates with "reillumination" or "restrike," during which the leader current rises dramatically (Les Renardières Group, 1974). In the rocket-triggered lightning, the initial upward positive leader develops with a sequence of current pulses varying over a broad range (Lu et al, 2016). Such phenomenon is poorly understood, and the discussion is beyond the scope of this paper.…”

Section: On the Application Scope Of The Experimental Datamentioning

confidence: 99%

On the Velocity‐Current Relation of Positive Leader Discharges

Zhao¹,

Liu²,

Wang³

et al. 2019

Geophysical Research Letters

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The velocity‐current relation of positive leader discharges is of great importance in the research of lightning physics. However, the measured data in a wide range of current up to several hundred amperes are not available so far. To fill the gap, experiments on positive leader discharges in long air gaps under lightning impulses were carried out on the test site at an altitude of 2.1 km. The velocity and current of positive leaders were measured with the synchronized discharge current and high‐speed video frames. An empirical formula for the velocity‐current relation of positive leaders is given with the leader current up to 500 A. The measurements are also compared with the numerical simulations, and it is suggested that the initial tip radius of a propagating leader grows as the leader current increases.

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“…Lu et al () examined the magnetic field ( B field) signals at close range by using the low‐frequency magnetic sensor during the SHandong Triggering Lightning Experiment (SHATLE) campaign of 2014. Benefitting from the high sensitivity of the sensor, the B field signals during the very initial stage of triggered lightning were clearly observed, even during the weak discharge processes whose current waveform could not be well discerned in the measurement (e.g., Lu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Electromagnetic Signals During the Initial Stage of Negative Rocket‐Triggered Lightning

Fan

Jiang

et al. 2018

JGR Atmospheres

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With the measurements in SHandong Triggering Lightning Experiment and GuangdongComprehensive Observation Experiment on Lightning Discharge in China, we examine the electromagnetic signals associated with the upward positive leaders during the initial stage of negative triggered lightning. The magnetic field (B field) signals measured at close range (<100 m) for both sites can be divided into two categories (i.e., impulsive and ripple pulses) according to the discernibility of separation between individual pulses. The impulsive pulses are well simulated by using the transmission line model, which suggests that these pulses are generated by leader current pulses propagating downward along the steel wire. Because the length of extended leader channel ahead of the wire is not negligible during the stage of ripple pulses, the waveform of impulsive current pulses is changed after traveling through the high impedance leader channel. Taking the filtered current pulse as the input variable, the waveform of ripple pulse can be simulated properly, which indicates that ripple pulses are caused by the attenuation of impulsive current along prolonging leader channel. In addition, the paper analyzes the fast electric field (E field) changes measured at 60-m range from the launching site during the initial stage by using the transmission line model and shows that the polarity of E field change at a given range is determined by the inception height of upward leader, namely the surface E field change caused by the individual charge transfer of initial upward leader also involves the problem of reverse distance as present for a vertical dipole. Plain Language SummaryLightning can occur at a predictable time and place by using the technique of rocket-triggered lightning, which launches a small rocket trailing a grounded steel wire toward the charged thundercloud overhead. Therefore, the technique facilitates the research of lightning discharges and their electromagnetic effects. At the beginning of triggered lightning, a sustained train of current pulses can be measured at the base of discharge path, and the synchronous electromagnetic field signals can also be recorded by the electric and magnetic sensors deployed around the rocket launching site. The paper focuses on the characteristics of electromagnetic signals measured at close range (<100 m) during the SHandong Triggering Lightning Experiment and Guangdong Comprehensive Observation Experiment on Lightning Discharge (two experimental sites of triggered lightning in China) campaign. The main contributions of this article include two aspects: first, we clarify the relationship between the electromagnetic signals and current pulses during the initial stage of triggered lightning; second, we demonstrate the influences of the triggering height on the polarity of electric field waveform.

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Characterization of initial current pulses in negative rocket‐triggered lightning with sensitive magnetic sensor

Cited by 23 publications

References 41 publications

Underground Measurement of Magnetic Field Pulses During the Early Stage of Rocket‐Triggered Lightning

Underground Measurement of Magnetic Field Pulses During the Early Stage of Rocket‐Triggered Lightning

On the Velocity‐Current Relation of Positive Leader Discharges

Characteristics of Electromagnetic Signals During the Initial Stage of Negative Rocket‐Triggered Lightning

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