A comparison of intracloud and cloud-to-ground lightning discharges

Abstract. Pulse trains superimposed on the initial part of the electric field change of positive ground flashes are investigated. The characteristics of these pulse trains are found to be different from those of negative ground flashes and cloud flashes. Each pulse included in a pulse train appears as a bipolar waveform with pulse width from 5 to 52 •s and a mean of 18 •s. The time intervals between successive pulses are 10 to 180 •s with a mean of 54 •s. For each bipolar pulse, the ratio of the peak amplitude of the initial polarity to the maximum overshoot amplitude ranges from 0.4 to 4.7 with a mean value of 1.3. The ratio of maximum peak amplitude of successive pulses to the amplitude of the following return-stroke peak ranges from 0.02 to 1.9 with a mean of 0.27. IntroductionThe initial breakdown process in a lightning discharge is a precursor to both ground and cloud flashes. This process has been studied from the early days of lightning research. For negative cloud-to-ground lightning, according to Beasley et al. [1982], the electric field change prior to the first return stroke in a negative cloud-to-ground flash has two portions: the first they term "preliminary variations" which has a duration of about 90 ms and the second " InstrumentationOur study is primarily concerned with the initial breakdown process in positive cloud-to-ground lightning flashes. Electric field waveforms associated with lightning discharges have been recorded at three sites in the Hokuriku district area by using, a "wideband slow antenna" having frequency ranges from 0.2 Hz to 0.5 MHz. The system used in this study is similar to the system described by Brook et al.

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“…As for preliminary breakdown pulses preceding the negative ground flash, Kitagawa and Brook [1960] 35 '''1''''1 .... I ....…”

Section: Discussion and Summarymentioning

confidence: 99%

Electric fields of initial breakdown in positive ground flash

Ushio¹,

Kawasaki²,

Matsuura³

et al. 1998

J. Geophys. Res.

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“…The mechanism whereby first return stroke is preceded by such long duration electric field change has not been completely understood. Clarence and Malan (1957) attributed it to processes that initiate stepped leader, while Kitagawa and Brook (1960) and Thomson (1980) insisted that it should be regarded as independent intracloud processes. To some extent we agree to the latter.…”

Section: Discussionmentioning

confidence: 99%

Characteristics of Cloud-to-Ground Lightning in Chinese Inland Plateau.

Qie

Wang

et al. 2002

Journal of the Meteorological Society of Japan

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Characteristics of cloud-to-ground (CG) lightning flashes in the Chinese inland plateau have been analyzed by using the data obtained from a broadband slow antenna system, with a time resolution of 1 microsecond in 1996, and a CG lightning location network from 1997 to 1998. It has been found that lightning discharges in a plateau summer thunderstorm usually present some special characteristics compared with the typical summer thunderstorm. On the average, positive CG flashes comprised 16% of total CG flashes in the Chinese inland plateau. After comparison with radar echo, it is found that some weak thunderstorms are conducive to positive CG flashes. The first return strokes are usually preceded by a long duration preliminary breakdown process which is characterized by discrete bipolar pulses for both positive and negative CG flashes. The mean duration of electric field change prior to first return stroke is about 126.1 ms, in which 23% exceeds 200 ms for negative CG flashes, and the corresponding value is 165.1 ms for positive CG flashes. The mean interval between 152 successive analyzed pulses is 211:0 G 148:0 ms, and the total duration of the pulses is 32:0 G 20:0 ms for negative CG flashes, while the mean time interval between the 50 analyzed pulses is 165:0 G 120:0 ms and the total duration of pulses is 27:0 G 19:0 ms for positive CG flashes. Other discharge features, such as interstroke intervals, amplitude distribution of the subsequent return strokes and etc., are also analyzed in the paper.

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“…They used a capacitive antenna originally developed by M. Brook at Langmuir for studying fast transients in the vertical electric field ("fast E-field changes"), i.e., sferics in the VLF/LF spectrum (Kitagawa and Brook, 1960). Some of the NBE sferics were followed by a distinctive pair of secondary echoes, delayed by as much as a few-hundred microsec from the initial ground-wave signal.…”

Section: A R Jacobson and T E L Light: Revisiting "Narrow Bipolamentioning

confidence: 99%

Revisiting "Narrow Bipolar Event" intracloud lightning using the FORTE satellite

Jacobson

Light

2012

Ann. Geophys.

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Abstract. The lightning stroke called a "Narrow Bipolar Event", or NBE, is an intracloud discharge responsible for significant charge redistribution. The NBE occurs within 10-20 µs, and some associated process emits irregular bursts of intense radio noise, fading at shorter timescales, sporadically during the charge transfer. In previous reports, the NBE has been inferred to be quite different from other forms of lightning strokes, in two ways: First, the NBE has been inferred to be relatively dark (non-luminous) compared to other lightning strokes. Second, the NBE has been inferred to be isolated within the storm, usually not participating in flashes, but when it is in a flash, the NBE has been inferred to be the flash initiator. These two inferences have sufficiently stark implications for NBE physics that they should be subjected to further independent test, with improved statistics. We attempt such a test with both optical and radio data from the FORTE satellite, and with lightning-stroke data from the Los Alamos Sferic Array.We show rigorously that by the metric of triggering the PDD optical photometer aboard the FORTE satellite, NBE discharges are indeed less luminous than ordinary lightning. Referred to an effective isotropic emitter at the cloud top, NBE light output is inferred to be less than ∼3 × 10 8 W.To address isolation of NBEs, we first expand the pool of geolocated intracloud radio recordings, by borrowing geolocations from either the same flash's or the same storm's other recordings. In this manner we generate a pool of ∼2 × 10 5 unique and independent FORTE intracloud radio recordings, whose slant range from the satellite can be inferred. We then use this slant range to calculate the Effective Radiated Power (ERP) at the radio source, in the passband 26-49 MHz. Stratifying the radio recordings by ERP into eight bins, from a lowest bin (<5 kW) to a highest bin (>140 kW), we document a trend for the radio recordings to become more isolated in time as the ERP increases. The highest ERP bin corresponds to the intracloud emissions associated with NBEs.At the highest ERP, the only significant probability of temporal neighbors is during times following the high-ERP events. In other words, when participating in a flash, the high-ERP emissions occur at the apparent flash initiation.

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A comparison of intracloud and cloud-to-ground lightning discharges

Cited by 216 publications

References 12 publications

Electric fields of initial breakdown in positive ground flash

Electric fields of initial breakdown in positive ground flash

Characteristics of Cloud-to-Ground Lightning in Chinese Inland Plateau.

Revisiting "Narrow Bipolar Event" intracloud lightning using the FORTE satellite

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A comparison of intracloud and cloud-to-ground lightning discharges

Cited by 216 publications

References 12 publications

Electric fields of initial breakdown in positive ground flash

Electric fields of initial breakdown in positive ground flash

Characteristics of Cloud-to-Ground Lightning in Chinese Inland Plateau.

Revisiting &quot;Narrow Bipolar Event&quot; intracloud lightning using the FORTE satellite

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Revisiting "Narrow Bipolar Event" intracloud lightning using the FORTE satellite