Occurrence of narrow bipolar pulses between negative return strokes in tropical thunderstorms

Mohd Esa, Mona Riza and Ahmad, Mohd Riduan and Cooray, Vernon (2014) Occurrence of narrow bipolar pulses between negative return strokes in tropical thunderstorms. In: ICLP, 13-17 October 2014, Shanghai, China. (In Press)

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This paper reports a recent observation of Narrow Bipolar Pulses (NBPs) occurrence between return strokes (RSs) of negative cloud-to-ground (CG) flashes in tropical thunderstorms. Similar observation by Nag et al. (2010) has been reported from Florida thunderstorms. Electric field change measurement has been conducted in Southern Malaysia (latitude 1°34ʹ′12.00ʺ″N, longitude 103°38ʹ′42.00ʺ″E) during Northeastern monsoon season between November and December 2012. From the total 173 recorded NBPs, the majority (105 pulses or 60.7%) appeared to occur as an isolated NBP event with 81 single NBPs and 24 multiple NBPs. The remaining 39.3% of NBPs have been observed to occur as part of CG and IC flashes. We observed the occurrence of 22 single NBPs and 1 pair of positive NBP (+NBP) between the RSs. We believe this is the first time the occurrence of multiple NBP between RSs is reported since Nag et al. (2010) found them only in the case of isolated NBPs with 3 pairs of +NBPs; about 4% from the total examined NBPs. Out of 22 single NBPs between RSs, only 9 (4 +NBPs and 5 –NBPs) can be located within horizontal distance ranging from 20-45 km. Fig. 1 shows an example of electric field change record of the occurrence of single +NBP between RS2 and RS3. Fig. 2 shows the location of +NBP, RS1 and RS3 at 36 km, 42 km and 36 km from the observation station (OS), respectively. The horizontal distance between RS1 and +NBP is 6 km and the following RS3 has occurred at 4 km away from the +NBP location. On the other hand, the pair of +NBP is located at horizontal distances of 72 km (+NBP1) and 74 km (+NBP2) from the OS as shown in Fig. 3. The first NBP (+NBP1) is observed to occur between RS1 (70 km from OS) and RS2 while the second NBP (+NBP2) is observed to occur between RS3 (73 km from OS) and RS4 as shown in Fig. 4.

Item Type: Conference or Workshop Item (Poster)
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Electronics and Computer Engineering > Department of Computer Engineering
Depositing User: En. Mohd Riduan Ahmad
Date Deposited: 19 Jun 2014 03:05
Last Modified: 28 May 2015 04:26
URI: http://eprints.utem.edu.my/id/eprint/12638
Statistic Details: View Download Statistic

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