Statistical Analysis on Preliminary Breakdown Pulses of Positive Cloud-to-Ground Lightning in Malaysia (original) (raw)
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Negative cloud-to-ground lightning flashes in Malaysia
Journal of Atmospheric and Solar-Terrestrial Physics, 2014
The characteristics of the negative cloud-to-ground lightning flashes in Malaysia are studied by analyzing the electric fields generated by the whole flash in nanosecond resolution. A total of 405 strokes obtained from 100 successive negative cloud-to-ground lightning flashes were analyzed, which were recorded from seven convective thunderstorms during the southwest monsoon period, i.e. from April to June 2009. It was found that the total number of interstroke intervals has an arithmetic mean value of 86 ms, a geometric mean value of 67 ms and does not depend on the return stroke order. Of the 100 negative ground flashes, 38 flashes (38%) have at least one subsequent return-stroke (SRS) whose electric field peak was greater than that of the first return-stroke (RS). Furthermore, 58 (19%) out of 305 SRS have electric field peak larger than those of the first RS. The arithmetic and geometric mean ratio between the peak electric field of the SRS and the peak electric field of the first RS are 0.7 and 0.6, respectively. The percentage of single-stroke flashes was 16% while the mean number of strokes per flash and maximum number of stroke per flash were 4 and 14, respectively.
Comparison of Captured Lightning Waveforms in Malaysia with Theoretical Models
The cloud-to-ground lightning contains one or more sporadic discharges. This process includes a combination of pre-starting sections before the return strokes (RSs). The discharge trains are investigated by capturing the electric field pulses known as breakdown pulses which precede the first return stroke. In a lightning flash, the preliminary breakdown pulses (PBPs) usually happen before the stepped leaders. The characteristics of the lightning breakdown processes are not entirely known yet. The BIL model has been used as the simplest preliminary breakdown pulse analyzer in previous studies. The BIL model is entirely successful in depicting incipient processes of the cloud-to-ground lightning. The BIL model is practical as a general depiction but the details of the breakdown process differ from study to study. In this paper, the preliminary breakdown pulse (PBP) train is analyzed in the cloud-to-ground (CG) lightning waveforms captured in Malaysia using a broadband antenna.
Journal of Atmospheric and Solar-Terrestrial Physics, 2012
This is the new study of the electric field changes generated by the preliminary 10 breakdown for positive cloud-to-ground flashes which concerning on the association of 11 slow field changes in preliminary breakdown process. In this study, a 107 positive cloud-12 to-ground lightning flashes recorded from the total of 14 thunderstorms generated by the 13 whole flash were examined. The electric fields were measured with nanosecond 14 resolution by using the slow electric field, fast electric field and narrowband radiation 15 field at 3 and 30 MHz signals simultaneously. Our result shows that there is a pre-starting 16 time, i.e. the duration between the first preliminary breakdown pulse and slow field 17 changes starting point, which is found to be after the first preliminary breakdown pulse.
Unusually long duration lightning electric field return strokes in Malaysia
2014 International Conference on Lightning Protection (ICLP), 2014
This paper presents the characteristics of lightning generated vertical electric field waveforms recorded in Malaysia. The focus of the study was the waveforms with unusually long zero crossing times. A total of 207 lightning ground flash records were analyzed out of which nine flashes contained the return stokes that have long durations of zero crossing. In contrast to the majority of return strokes that have zero crossing times in the order of 40-70 I1s, these unusual return stroke waveforms are characterized by zero crossing times between 0.66 ms to 7.96 ms.