| Autor: |
Rahman, Puteri Nur Suhaila Ab., Baharudin, Zikri Abadi |
| Předmět: |
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| Zdroj: |
International Journal of Simulation: Systems, Science & Technology; 2016, Vol. 17 Issue 41, p1-6, 6p |
| Abstrakt: |
The Preliminary Breakdown Pulses (PBP) train preceding the first return stroke either in negative or positive cloud-toground flash consistently found to be a typical profile of lightning ground flashes. This analysis is important as a scientific value for electromagnetic compatibility community, lightning protection and meteorology science for designing a proper lightning detection system. This study greatly become important in lightning study in order to understand the initiation process of lightning ground flashes. Mostly, the investigators reported that the polarities of bipolar train pulses are identical to that of first return stroke. However, it is very rare if the polarity of bipolar PBP train pulses become non identical compared to negative return stroke pulse. The problematic issue of non identical of PBP train polarity compared to the first return stroke may have tendency to cause misleading of lightning ground flashes type (positive/negative) especially for the most highest amplitude of PBP train pulse that comparable or higher than the first return stoke amplitude. The problem above motivated our team to explore the criteria in PBP train which were not same polarity as that of negative return stroke. Therefore, the electric fields generated by lightning negative ground flashes in Malaysia were measured with nanosecond resolution using the combination of flat plat antenna, fast electric field buffer and recorder (Yokogawa 1000 and HDO 4240 LeCroy). The numbers of 721 of negative ground flashes were analyzed and 43 samples of negative ground flashes were found to have PBP train polarities which were not identical to that of negative first return stroke. It means that the amount of uncommon PBP from the total of the sample is considered very small (6%). However some thunderstorm event we found to have significant amount of uncommon PBP which suggested that this profile may depend on the type of thunderstorm and season. Furthermore, uniquely the majority of stroke number of uncommon PBP is single stroke. It is suggested that a large number of data need to be analyzed in future in order to have more comprehensive information. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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