Features of positive ground flashes observed in Kathmandu Nepal

Adhikari, Pitri Bhakta; Sharma, Shailesh; Baral, K. N.

doi:10.1016/j.jastp.2016.04.016

Cited by 17 publications

(11 citation statements)

References 16 publications

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“…The arithmetic mean (AM) and geometric mean (GM) of interstroke intervals are 122.2 and 64.4 ms when including the largest value and 103.2 and 61.4 ms when excluding the largest value. As summarized in Table 1, many other studies also reported the large range of interstroke intervals from several milliseconds to hundreds of milliseconds (Adhikari et al, 2016;Baharudin et al, 2016;Cooray & Pérez, 1994;Nag & Rakov, 2012;Qie et al, 2013). As for the mean values, the AM is easily influenced by extremely small or large values, so the GM is more appropriate to measure the average interstroke interval, and as summarized in Table 1, GM values in most studies are in the range of 50 to 100 ms.…”

Section: Interstroke Intervalsmentioning

confidence: 98%

Multiple‐Stroke Positive Cloud‐to‐Ground Lightning Observed by the FALMA in Winter Thunderstorms in Japan

Wang

Takagi

2020

JGR Atmospheres

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Multiple-stroke (MS) positive cloud-to-ground (+CG) lightning flashes are rarely reported, especially those with high-quality location information. In this study, we report 47 MS +CG flashes observed in winter thunderstorms in Japan with a 14-site fast antenna lightning mapping array (FALMA). MS +CG flashes account for 18% of +CG flashes. The mean multiplicity of all +CG flashes is 1.24, and the maximum multiplicity is 5. Interstroke intervals have a very large range from 1.0 to 1,320.6 ms with the geometric mean of 64.4 ms. In three flashes, interstroke intervals smaller than 2 ms are observed, and corresponding positive strokes are inferred to be produced by two branches of the same positive leader. Horizontal distances between sequential positive strokes range from 1.1 to 37.3 km with the geometric mean of 9.7 km. No subsequent strokes struck at the same location as a previous stroke. Distances between sequential strokes are generally much larger than distances between first strokes and lightning initiation locations. Subsequent stroke peak amplitudes are on average 0.45 of first stroke peak amplitudes. In 39 flashes (83%), the first stroke is stronger than the largest subsequent stroke in the same flash. Subsequent stroke amplitudes are weakly correlated with the time difference from the previous stroke. Origination mechanisms of positive leaders initiating first and subsequent positive strokes are discussed. It is very likely that positive leaders for most subsequent strokes originate from in-cloud negative leader channels, but origination mechanisms for positive leaders initiating first strokes are more varied.

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Section: Interstroke Intervalsmentioning

confidence: 98%

Multiple‐Stroke Positive Cloud‐to‐Ground Lightning Observed by the FALMA in Winter Thunderstorms in Japan

Wang

Takagi

2020

JGR Atmospheres

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“…In this paper, the digitizer volts are used to measure the electric field signatures. A similar electric field measuring system is described in various other experiments also [ 25 – 30 ].…”

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Comparing the Wave Characteristics of Breakdown Pulses of the Lightning Waveforms in the Himalayan Region

Adhikari

2021

The Scientific World Journal

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We have analyzed the breakdown pulse train with or without the main event in this paper. Among the selected 81 flashes, 36 flashes are starting positively, and 45 are starting negatively. Also, 58 flashes contain positive pulses, and 67 flashes contain negative pulses, whereas 44 flashes contain both positive and negative pulses. Among these 81 flashes, 22 flashes follow the main events, and the rest are isolated events. In this study, we got the main duration of PB pulses as 1.94 ms and the time interval between the breakdown pulse and return stroke as 61.49 ms. On taking each pulse train, we found the rise time to be 2.6 μs, zero-crossing time 14.95 μs, and the time interval between pulses 199.3 μs. The largest pulse amplitude ratio in the preliminary breakdown pulse to the main event return stroke was 0.43.

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“…e signals so received were recorded by the Pico-scope whose window size was 500 ms at the sampling rate of 1.25 GS/sec. e recording system was similar to what was described previously [24][25][26][27]. e zero-to-peak rise time of the antenna system for a step pulse was less than 30 ns.…”

Section: Instrumentation and Measurementmentioning

confidence: 99%

Characteristic Features of Electric Fields Radiated by Cloud Flashes in Himalayan Region

Adhikari

Sharma

2020

International Journal of Antennas and Propagation

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Electric fields radiated by cloud flashes that occurred over the rugged terrain of mountainous country Nepal were recorded, analysed, and compared with those from different geographical regions. The total duration of the flash varies from 80 to 469.5 ms. The majority of the cloud flashes were of two stages: the first stage of the majority of the flashes was found to consist of large microsecond scale bipolar pulses having negative initial polarity and the late stage consists of submicrosecond scale pulses having both positive and negative initial polarities. The average durations of the first and second stages are 11.23 and 66.79 ms, respectively, and the time gap between them is 53.57 ms. The cloud pulses led by the negative initial polarity pulses are more compactly distributed and are higher in mountainous countries as compared to those of flashes lead by positive initial polarity pulses, with the average values of interpulse interval being 211.42 and 309.79 μs, respectively.

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Features of positive ground flashes observed in Kathmandu Nepal

Cited by 17 publications

References 16 publications

Multiple‐Stroke Positive Cloud‐to‐Ground Lightning Observed by the FALMA in Winter Thunderstorms in Japan

Multiple‐Stroke Positive Cloud‐to‐Ground Lightning Observed by the FALMA in Winter Thunderstorms in Japan

Comparing the Wave Characteristics of Breakdown Pulses of the Lightning Waveforms in the Himalayan Region

Characteristic Features of Electric Fields Radiated by Cloud Flashes in Himalayan Region

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