| 1. |
- Sabri, Muhammad Haziq Mohamad, et al.
(författare)
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Environmental Analysis of Quasi-Static Electric Field Changes of Tropical Lightning Flashes
- 2019
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Ingår i: Ekoloji. - 1300-1361. ; 28:107, s. 373-378
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Tidskriftsartikel (refereegranskat)abstract
- The environmental conditions leading to the bouncing-wave discharge and the subsequent electron beam remain to be investigated in more detailed future studies. The analysis of quasi-static initial electric field changes (IECs) were found at the beginning of all 24 lightning flashes detected within reversal distance (22 Negative Cloud-to-Ground (–CG) and 2 normal Intra-Cloud (IC) flashes) in a tropical storm on June 15th, 2017 close to our station in Malacca, Malaysia (2.314077° N, 102.318282° E). The IECs durations averaged 4.28 ms for –CG flashes (range 1.48 to 9.45 ms) and averaged 11.30 ms for normal ICs flashes (range 7.24 to 15.35 ms). In comparison to Florida storms, the duration of IECs for –CG and IC flashes were 0.18 ms (range 0.08 to 0.33 ms) and 1.53 ms (range 0.18 to 5.70 ms), respectively. Moreover, the magnitudes of E-change for tropical thunderstorm were 0.13 V/m (range 0.03 to 0.44 V/m) for –CG flashes and -0.20 V/m (range -0.13 to -0.27 V/m) for IC flashes. The E-change magnitudes of tropical flashes are significantly larger than Florida flashes.
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| 2. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Chaotic Pulse Train in Cloud-to-Ground and Cloud Flashes of Tropical Thunderstorms
- 2014
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Konferensbidrag (refereegranskat)abstract
- In this paper, we report for the first time the observation of chaotic pulse train (CPT) preceding natural subsequent negative return strokes and also CPT occurrence in IC flashes from tropical thunderstorms in South Malaysia. In CG flashes, all CPTs were occurred in between return strokes with 41.1% have occurred between the first and second return strokes. The maximum number of CPT in one sequence is 3, which can be observed between the first and third return strokes only. In IC flashes, all CPTs were observed to occur in between IC flash pulses.
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| 3. |
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| 4. |
- Sabri, Muhammad Haziq Mohammad, et al.
(författare)
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Very High Frequency and Microwave Radiation Associated with Initial Breakdown Process in CG Lightning Flashes from Tropical Storms
- 2021
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Ingår i: 2021 35TH INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP) AND XVI INTERNATIONAL SYMPOSIUM ON LIGHTNING PROTECTION (SIPDA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665423465
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Konferensbidrag (refereegranskat)abstract
- We present the observation of VHF and microwave radiation pulses associated with initial breakdown process of five negative cloud-to-ground (-CG) flashes from two tropical storms. The -CG flashes were detected within and beyond reversal distances with the locations of the first return stroke were less than 10 km. Out of five flashes, only one detected with initial electric field change (IEC) process. Both VHF and microwave pulses were detected before the first classic IB pulse and the first microwave pulses were found to lead the first VHF pulses ranging between 0.03 and 23.9 mu s.
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| 5. |
- Yusop, Norbayah, et al.
(författare)
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Cloud-to-Ground lightning observations over the Western Antarctic region
- 2019
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Ingår i: Polar Science. - : ELSEVIER. - 1873-9652 .- 1876-4428. ; 20, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the observations and characterization of Cloud-to-Ground (CG) lightning activity in Western Antarctica in a region that covers the Amundsen/Bellingshausen Sea (ABS), the Antarctic Peninsula (AP) and the Weddell Sea (WS). Lightning data have been collected by a lightning detector (Boltek LD-350) and an atmospheric electric field mill (EFM-100) sensors deployed at the Carlini Base on the Antarctic Peninsula (CARL: 62.23 degrees S, 58.63 degrees W). The flash rate and flash multiplicity were analysed for three different seasons within a 1,000 km range, starting at the end of summer (February 2017) and ending in winter (July 2017). Three storm days for each month (within the 1,000 km radius from the LD sensor) with three composite active thunderstorms (labelled as Storm region A, B, and C) for each day have been selected from a collection of storm days between February and July 2017. A total of 355,899 flashes have been recorded with 156,190 Positive CG and 199,709 Negative CG flashes from these 54 thunderstorms. In total, Positive CG flash counts made up around 43.9% of the total detected CG flashes. Most of the Positive CG flashes (> 80%) had only 1 or 2 strokes with a maximum number of 5. For Negative CG flashes, the average multiplicity and the maximum multiple stroke were 1.2 and 16 respectively. Most CG flashes were detected during the summer and fall months. Positive CG flashes were prevalent in Western Antarctic storms even during the winter. The mean, median and range of the ratio of Positive CG to Negative CG flashes were 0.7, 0.718 and 0.217-1.279, respectively.
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| 6. |
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| 7. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Emission Heights of Narrow Bipolar Events in a Tropical Storm over the Malacca Strait
- 2017
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Ingår i: 2017 International Conference On Electrical Engineering And Computer Science (Icecos). - : IEEE. - 9781479976751 - 9781479976768 - 9781479976744 ; , s. 305-309
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Konferensbidrag (refereegranskat)abstract
- Emission heights for narrow bipolar events (NBEs) have been reported mostly from observations at mid latitudes but none have been reported from tropical regions. In this paper, we are reporting for the first time the heights of NBE emissions from a tropical storm over the Malacca Strait, a narrow water passage between the Malay Peninsula and Sumatra Island. A total of 49 positive NBEs (+NBEs) were detected from the storm. The NBE activity can be divided into two stages according to the emission heights and radar reflectivity data. The first stage (or S1) lasted for only 6 minutes, started with the first detected NBE, and produced 20 NBEs (41%). The emission heights ranged between 12.0 and 16.7 km. Radar reflectivity data showed that the storm reached maximum values at 55 dBZ within the period S1. In contrast, the second stage (S2) lasted longer (32 minutes) and produced 29 NBEs (59%). The emission heights were lower and ranged from 8.5 to 13.7 km. Radar reflectivity data showed that the storm reached maximum values at 50 dBZ within the period S2.
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| 8. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Interference from cloud-to-ground and cloud flashes in wireless communication system
- 2014
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Ingår i: Electric power systems research. - : Elsevier BV. - 0378-7796 .- 1873-2046. ; 113, s. 237-246
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Tidskriftsartikel (refereegranskat)abstract
- In this study, cloud-to-ground (CG) flash and intra-cloud (IC) flash events that interfere with the transmission of bits in wireless communication system operating at 2.4 GHz were analyzed. Bit error rate (BER) and consecutive lost datagram (CLD) measurement methods were used to evaluate BER and burst error from 3 tropical thunderstorms on November 27, 28, and 29 during 2012 northeastern monsoon in Malaysia. A total of 850 waveforms from the electric field change recording system were recorded and examined. Out of these, 94 waveforms of very fine structure were selected which matched perfectly with the timing information of the recorded BER. We found that both CG and IC flashes interfered significantly with the transmission of bits in wireless communication system. The severity of the interference depends mainly on two factors namely the number of pulses and the amplitude intensity of the flash. The interference level becomes worst when the number of pulses in a flash increases and the amplitude intensity of pulses in a flash intensifies. During thunderstorms, wireless communication system has experienced mostly intermittent interference due to burst error. Occasionally, in the presence of very intense NBP event, wireless communication system could experience total communication lost. In CG flash, it can be concluded that PBP is the major. source of interference that interfered with the bits transmission and caused the largest burst error. In IC flash, we found that the typical IC pulses interfered the bits transmission in the same way as PBP and mixed events in CG flash and produced comparable and in some cases higher amount of burst error. NBP has been observed to interfere the bits transmission more severely than typical IC and CG flashes and caused the most severe burst error to wireless communication system.
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| 9. |
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| 10. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Lightning interference in multiple antennas wireless communication systems
- 2012
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Ingår i: Journal of Lightning Research. - : Bentham open. - 1652-8034. ; 4, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes the interference of lightning flashes with multiple antennas wireless communicationsystems operating in the microwave band at 2.4 GHz and 5.2 GHz. A bit error rate (BER) measurement method was usedto evaluate BER and packet error rate (PER) during 5 heavy thunderstorms on January 25 and March 17 to 20, 2011,respectively. In addition, BER measurements also were done on January 21 and March 30, 2011 under fair weather (FW)conditions providing a baseline for comparison. The Transmitter-Receiver separation was fixed at 10 meter with line-ofsight(LOS) consideration. We infer that lightning interfered with the transmitted digital pulses which resulted in a higherrecorded BER. The maximum recorded BER was 9.9·10-1 and the average recorded BER and PER were 2.07·10-2 and2.44·10-2 respectively during the thunderstorms with the average fair weather BER and PER values under the influence ofadjacent channel interference (ACI) and co-channel interference (CCI) being 1.75·10-5 and 7.35·10-6 respectively. Weconclude that multiple antennas wireless communication systems operating at the microwave frequency can besignificantly interfered by lightning.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Preliminary Observations of Lightning Signature At 2400 MHz in Sweden Thunderstorm
- 2012
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Konferensbidrag (refereegranskat)abstract
- This paper presents a preliminary observation of lightning signature at 2400 MHz. We believe this is the first time such observation was made in such frequency band. One positive ground discharge and one cloud discharge waveforms have been selected from a collection of waveforms recorded using fast and slow broadband antenna systems. In addition, waveforms recorded directly from 2400 MHz whip antenna associated with the selected ground and cloud discharges waveforms were observed. The measurements were carried out in Uppsala, Sweden in July 2012. We discovered a possible lightning signature at 2400 MHz with the existence of bursts of pulses happened to occur simultaneously with preliminary breakdown, negative return stroke and cloud pulses. These bursts of pulses possibly interfered in some ways with the transmitted bits leading to higher recorded error bits during the thunderstorm.
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| 15. |
- Ahmad, Mohd Riduan, et al.
(författare)
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Similarity between the Initial Breakdown Pulses of Negative Ground Flash and Narrow Bipolar Pulses
- 2014
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Ingår i: 2014 INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP). - : IEEE conference proceedings. - 9781479935444 ; , s. 810-813
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Konferensbidrag (refereegranskat)abstract
- In this paper, temporal characteristics of several initial electric field pulses of preliminary breakdown process (PBP) from very close negative cloud-to-ground (CG) flashes are compared to close narrow bipolar pulses (NBPs) to observe any similarity that may exists. Interestingly, we found that the initial PBP pulses are similar to close NBP with zero crossing time less than 5 mu s, do not preceded by any slow field change and followed by pronounce static component. As NBPs are believed to be a result of relativistic runaway electron avalanches discharge, this finding is an indication that the initial electric field pulses of PBP are perhaps the result of the same discharge mechanism.
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| 16. |
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| 17. |
- Esa, Mona Riza Binti Mohd, et al.
(författare)
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Distinctive features of radiation pulses in the very first moment of lightning events
- 2014
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 109, s. 22-28
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the existence of distinctive features between 4 different types of lightning discharges, namely negative cloud to ground discharge (-CG), positive cloud to ground discharge (+ CG), cloud discharge (IC) and isolated breakdown discharge (IB). A total of 110 very fine structure waveforms of 44 CG, 16 +CG, 39 IC, and 11 IB discharges have been selected from a collection of 885 waveforms measured using fast electric field broadband antenna system. The measurements were carried out in Uppsala, Sweden from May to August 2010. We found that there are significant distinctions within the first 1 ms among different types of lightning discharges (-CG, +CG, IC, and IB). For example, the pulses in -CG discharges are more frequent than other discharges; the pulses in +CG discharges have the highest intensity and the IC discharge pulses tend to have shorter duration. o 2014 Elsevier Ltd. All rights reserved.
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| 18. |
- Esa, Mona Riza Mohd, et al.
(författare)
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Wavelet analysis of the first electric field pulse of lightning flashes in Sweden
- 2014
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Ingår i: Atmospheric research. - : Elsevier BV. - 0169-8095 .- 1873-2895. ; 138, s. 253-267
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the wavelet characteristics of the first electric field pulse of four different flash types namely negative cloud-to-ground flash (-CG), positive cloud-to-ground flash (+CG), cloud flash (IC) and isolated breakdown flash (IB). A total of 110 fine waveforms out of 885 were selected which have been recorded during summer between May and August 2010 in Uppsala, Sweden. The measurement was done by using an electric field broadband antenna system with the time resolution of 20 Megasample per second. Evidence from our wavelet analysis suggests that the ionization process during the initial leader development (coincide with the detection of the first electric field pulse) of at least three flashes (-CG, IC, and IB) in Sweden was dictated directly by the existence and magnitude of localized free ions region and lower positive charge center (p region). In general, we found that both single peak and multiple peaks pulses of the negative CG and IC flashes radiated energy at higher frequencies and gain larger bandwidth when compared to positive CG and IB flashes. We suggest that the initial leader development of both IC and negative CG flashes underwent very rapid and much more extensive ionization process when compared to the positive CG and IB flashes. In specific comparison between negative CG and IC flashes, both temporal and wavelet analyses suggest that the first electric field pulses of IC flash radiated energy at higher frequency in both single spread categories and radiated energy at lower frequency in both multiple spread categories when compared to the negative CG flash. This finding may explain the observation of much slower and less bright type alpha leader (ionization process not so extensive) compared to much faster and very bright type beta leader (ionization process very rapid and more extensive). As for positive CG and IB flashes, the single peak pulses of positive CG radiated energy at much higher frequency while the multiple peaks pulses radiated energy at much lower frequency than IB flash. We suggest that the initiation mechanism of positive CG was dictated directly by the background electric field between the main positive charge center and the ground, which is distinct from the initiation mechanism of IB flash. The presence of small magnitude of localized free ions region facilitated the rapidity of the ionization process in the initial leader development of IB flash.
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| 19. |
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| 20. |
- Mohd Esa, Mona Riza, et al.
(författare)
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Time-Frequency Profile of Discharge Processes Prior to the First Return Stroke
- 2014
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Ingår i: 2014 INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP). - : IEEE conference proceedings. - 9781479935444 ; , s. 1134-1137
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Konferensbidrag (refereegranskat)abstract
- We aim to investigate the time-frequency profile for sets of lightning processes that occurred prior to the first return stroke which include narrow bipolar pulses, preliminary breakdown pulses and stepped leaders. The work is mainly using the wavelet transformation in order to gain the frequency spectrum while not losing the time information of the located pulses. 2 sets of events that include the narrow bipolar pulse (NBP) followed by preliminary breakdown pulses (PBPs), stepped leaders (SLs) and the first return stroke (RS) are used in this paper. All selected data are recorded during northeastern monsoon season at the end of year 2012 in Malaysia. Parameters that used in this works includes the (1) upper and (2) lower frequency spectrum for both spectral and spread regions and (3) power spectrum. In average, the upper and lower frequency spectrum for NBP is at least 10 times higher when compare to the first return stroke. It is also found that the NBP radiates predominantly between 61 kHz and 168 kHz which much higher than the first return stroke with range from 2 kHz to 12 kHz. PBP pulses radiate intensely within 65 kHz to 1 MHz, whereas SL pulses radiate predominantly between 163 kHz and 455 kHz. In terms of power spectrum, PBP pulses tend to produce higher magnitude of power spectrum in the earlier stage and decreased towards the end of its process. In the contrary, SL pulses' power spectrum magnitudes are lower in the beginning and tend to increase when approaching to the first return stroke.
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| 21. |
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| 22. |
- Sabri, Muhammad Haziq Mohammad, et al.
(författare)
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A study of cloud-to-ground lightning flashes initiated by fast positive breakdown
- 2022
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Ingår i: Atmospheric research. - : Elsevier. - 0169-8095 .- 1873-2895. ; 276
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examine the initiation event of two tropical negative cloud to ground (CG) lightning flashes within reversal distance (<8 km) detected on 12 (CG1) and 24 (CG2) November 2019, respectively. The CG flashes were recorded using a fast antenna (FA), slow antenna (SA), magnetic field (B-field), and very high frequency (VHF) sensors located at two observation stations (ST1 and ST2) 13.26 km apart. The key finding is that CG1 flash was initiated by a short VHF pulse followed by a VHF burst (fast positive breakdown) while CG2 flash was initiated by a VHF burst (fast positive breakdown) not preceded by a short VHF pulse. The VHF burst was a precursor for initiation of a narrow bipolar event (NBE)-like pulse and initial electric field changes (IECs). Based on the VHF interferometer map, the VHF sources of NBE-like pulses have been propagated upward predominantly vertical. The initiation altitude, total length of the VHF sources propagation, estimated velocity of NBE-like pulse for CG1 flash were 4.5 +/- 0.5 km, 1.9-3.8 km, and 2.4 x 108 to 4.8 x 108 ms-1, respectively, and for CG2 flash were 5.1 +/- 0.8 km, 0.2-3.0 km, and 2.7 x 107 to 4.1 x 108 ms-1, respectively. It is evident that IECs process has been initiated during fast positive streamers propagation. It can be suggested that the IECs process resulted from charge transfer during a fast positive breakdown. The durations and magnitudes of IECs for CG1 flash were 248.5 mu s and 27.97 V/m, respectively, and for CG2 flash were 265.8 mu s and 2.31 V/m, respectively.
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| 23. |
- Sabri, Muhammad Haziq Mohammad, et al.
(författare)
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Observation of tropical positive cloud-to-ground flashes accompanied by chaotic and regular pulse trains
- 2024
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier. - 1364-6826 .- 1879-1824. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the occurrence of chaotic pulse trains (CPTs) and regular pulse trains (RPTs) in tropical positive cloud-to-ground (CG) lightning flashes. These flashes are categorized into four types based on the initial polarity of the initial breakdown (IB) pulses and their relationship to the first return stroke (RS). A total of 71 positive CG flashes from five thunderstorm events were analyzed. The analysis reveals instances of CPTs and RPTs both before and after the first positive RS, along with the occurrence of mixed polarities in RPTs. Variations in IB pulse polarities and the presence of CPTs and RPTs before the first positive RS were observed, contrasting with previous findings in negative CG flashes. All positive CG flashes have been detected when cloud top height occurrences were between 12 and 18 km. In contrast, for negative CG flashes with CPTs and RPTs the cloud top height occurrences were between 5 and 12 km. It is interesting that CPTs and RPTs can be detected during IB process of positive CG flashes at relatively high altitude in the thundercloud. Perhaps due to low pressure at higher altitudes in the cloud, electrical process associated with CPTs and RPTs are easily discharged before the occurrence first positive return stroke. The altitudes of cloud top heights for the inverse polarity of IB pulses were located between 16 and 18 km. This research enhances the understanding of positive CG lightning initiation process and their relationship with CPTs and RPTs, as well as the occurrence of recoil leaders.
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| 24. |
- Sabri, Muhammad Haziq Mohammad, et al.
(författare)
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Temporal characteristics of positive cloud-to-ground flashes from tropical thunderstorms
- 2024
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Ingår i: Atmospheric research. - : Elsevier. - 0169-8095 .- 1873-2895. ; 309
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of positive cloud-to-ground (CG) lightning flashes proves to be a challenging task when compared to the negative CG flash which common happen in tropical region. This due to the positively charged clouds to reach higher altitudes to enable the transfer of electrical charges to the Earth's surface. With several sensors that deployed in the Malacca region (2.314077 degrees N, 102.318282 degrees E) such as the wide band fast and slow antenna, magnetic field sensors, and the electric field mill (EFM-100). This research study focuses on the temporal characteristics of positive CG lightning activity in the tropical region during September and October 2021. A total of 203 positive cloud-to-ground flashes were meticulously analyzed in the context of 16 thunderstorm events. Key findings highlight the consistent initiation of positive cloud-to-ground flashes through initial breakdown (IB) pulses, followed by the development of stepped leaders and subsequent return strokes. Notably, most positive cloud-to-ground events (72%) were observed as single strokes and the maximum multiplicity recorded being four subsequent return strokes. Furthermore, the analysis focuses into the temporal aspects of these lightning events, revealing average durations for various parameters, including rise-time (6.26 mu s), zero-crossing (26.43 mu s), pulse duration of the first RS (139.76 mu s), and the interval from the first IB to the first return stroke (134.19 ms). Additionally, the recorded data from the Electric Field Mill (EFM) instruments together with Constant Altitude Plan Position Indicator (CAPPI) radar demonstrate a notable correlation. Specifically, the electric field (E-field) values exhibit a discernible increase when positive cloud-to-ground lightning events are detected near the lightning sensor.
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| 25. |
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| 26. |
- Yusop, Norbayah, et al.
(författare)
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Seasonal Analysis of Cloud-To-Ground Lightning Flash Activity in the Western Antarctica
- 2019
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Ingår i: Atmosphere. - : MDPI. - 2073-4433. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a seasonal analysis of cloud-to-ground (CG) lightning flash activity in the Western Antarctica using a lightning detector sensor installed at the Carlini Base station. Data obtained from the detection system between February and December 2017 were analyzed. Three common locations and areas of composite active thunderstorms (labelled storm regions A, B, and C) were detected by the sensor within a 1000 km radius from the station. Storm region A was located to the northwest (N/W) of the station and covered the Amundsen/Bellingshausen Sea (ABS), whereas storm region C was located on the southeastern (S/E) side of the station over the Weddell Sea (WS), with distances ranging from 500 to 800 km and bearings of 270 degrees to 360 degrees and 90 degrees to 180, respectively. Storm region B was located around 100 km from the station with the bearings of stroke taken from 0 degrees to 360 degrees. A total of 2,019,923 flashes were detected, of which 43.01% were positive CG and 56.99% were negative CG flashes. The analysis revealed that more than 96% of the CG flashes (both positive CG and negative CG) were produced during the summer and fall seasons as compared with less than 4% during the winter and spring seasons. Most detected lightning strokes (>85%) were located in the central area around the station produced by storm region B and less than 15% were produced by storm region A and storm region C, located in the ocean areas over the Amundsen/Bellingshausen Sea and the Weddell Sea.
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| 27. |
- Ahmad, Mohd Riduan, 1980-
(författare)
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Interaction of Lightning Flashes with Wireless Communication Networks : Special Attention to Narrow Bipolar Pulses
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, the features of electric field signatures of narrow bipolar pulses (NBPs) generated by cloud flashes are investigated and their effects on wireless communication systems are studied. A handful amount of NBPs (14.5%) have been observed to occur as part of cloud-to-ground flashes in South Malaysia. Occurrence of NBPs in Sweden has been reported for the first time in this thesis. The electric field waveform characteristics of NBPs as part of cloud-to-ground flashes were similar to isolated NBPs found in Sweden and South Malaysia and also to those isolated NBPs reported by previous studies from various geographical areas. This is a strong indication that their breakdown mechanisms are similar at any latitudes regardless of geographical areas.A comparative study on the occurrence of NBPs and other forms of lightning flashes across various geographical areas ranging from northern regions to the tropics is presented. As the latitude decreased from Uppsala, Sweden (59.8°N) to South Malaysia (1.5°N), the percentage of NBP emissions relative to the total number of lightning flashes increased significantly from 0.13% to 12%. Occurrences of positive NBPs were more common than negative NBPs at all observed latitudes. However, as latitudes decreased, the negative NBP emissions increased significantly from 20% (Sweden) to 45% (South Malaysia). Factors involving mixed-phase region elevations and vertical extents of thundercloud tops are invoked to explain the observed results. These factors are fundamentally latitude dependent.In this thesis, the interaction between microwave radiations emitted by cloud-to-ground and cloud flashes events and bits transmission in wireless communication networks are also presented. To the best of our knowledge, this is the first time such effects are investigated in the literature. Narrow bipolar pulses were found to be the strongest source of interference that interfered with the bits transmission.
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| 28. |
- Baharin, Shamsul Ammar Shamsul, et al.
(författare)
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Electromagnetic Interference From Natural Lightning on 4G Communication Links
- 2024
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 12, s. 14870-14881
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Tidskriftsartikel (refereegranskat)abstract
- In this study, microwave radiation pulses emitted from natural lightning have been found to interfere with the Fourth Generation Long Term Evolution (4G LTE) mobile communication data transmission. Two sets of measurement instruments have been synchronized where lightning electric field sensor together with 4G LTE network were evaluated its performance under two conditions namely fair-weather (four cases) and storm (four lightning cases). The microwave radiation emitted from lightning was directly measured without the use of a mixer and down-convertor to ensure the preservation of information such as the number of pulses and amplitude. A client-server architecture has been set up for data transmission utilizing User Datagram Protocol (UDP) where the packets have been generated by using Internet Performance Working Group Third Version (Iperf3) platform. Under fair-weather conditions, the 4G LTE connection at both the client and server nodes demonstrated stability and experienced minimal impact. On the other hand, natural lightning electromagnetic interference disrupted the 4G LTE communication links. Among the four reported storms, three storms have affected the 4G LTE data transmission. The first and fourth storms resulted in a complete connection drop to zero, lasting for 4 minutes and 2 seconds and for 44 seconds, respectively. The observation of hundreds microwave radiation pulses, each characterized by individual oscillating features suggests a potential disruption to packet transmission. Moreover, negative could-to-ground (-CG) and intra-cloud (IC) lightning flashes have been identified as the primary sources of interference to the 4G LTE data transmission. This information could be useful for future studies and for developers working on improving the reliability and performance of 4G LTE networks, particularly in areas prone to thunderstorms.
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| 29. |
- Baharin, Shamsul Ammar Shamsul, et al.
(författare)
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Microwave and Very High Frequency Radiations of The First Narrow Initial Breakdown
- 2021
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Ingår i: 2021 35TH INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP) AND XVI INTERNATIONAL SYMPOSIUM ON LIGHTNING PROTECTION (SIPDA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665423465
-
Konferensbidrag (refereegranskat)abstract
- This paper reports the observation of microwave and very high frequency (VHF) radiation pulses associated with the first narrow (<10us) initial breakdown (IB) pulses of ten negative cloud-to-ground (-CG) flashes. The centre frequency of microwave and VHF sensors was 0.97 GHz and 60 MHz, respectively. We found that all microwave pulses were the initiation event led the first VHF pulses ranging between 0.03187 and 2.57968 mu s and led the first narrow IB pulses ranging between 0.02382 and 2.70202 mu s. Half of the VHF pulses were observed to lead the first narrow IB pulses ranging between 0.03453 and 0.128 mu s. Moreover, polarity of microwave radiation pulses was always positive while the polarity of the first narrow IB pulses always negative. On the other hand, half of VHF radiation pulses had the same polarity as microwave radiation pulses.
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| 30. |
- Baharin, Shamsul Ammar Shamsul, et al.
(författare)
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Microwave radiation associated with positive narrow bipolar events
- 2023
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier. - 1364-6826 .- 1879-1824. ; 242
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examined seven isolated positive Narrow Bipolar Events (NBEs), one positive NBE that initiated an IC flash progressed to a single-stroke Cloud-to-Ground (CG) flash, and one positive NBE that initiated an IC flash. Seven NBEs have been accompanied by significant Very-High Frequency (VHF) and microwave radiation pulses. We recorded all NBEs from two measurement stations (ST1 and ST2) separated at 13.3 km apart which consisted of fast antenna (FA) and slow antenna (SA) sensors, a magnetic field (B-field) sensor, a VHF sensor (60 MHz), and a microwave sensor (0.97 GHz). The waveforms were sampled at 2.5 GHz (400 ps). The key finding is that all microwave radiation pulses have been found to precede both the VHF radiation pulses and NBEs with average lead time of 63 +/- 39 ns and 122 +/- 143 ns, respectively. In comparison to stepped leader pulses or SLPs (conventional breakdown), the average lead time of microwave to VHF for NBEs (fast breakdown) was 88% faster compared to the average lead time of microwave to VHF for SLPs. Moreover, the average lead time of VHF to NBEs was 56% faster when compared to the average lead time of VHF to SLPs. The VHF interferometer map for an isolated NBE (NBE6) showed upward propagation of VHF radiation sources (fast negative breakdown) with initiation altitude, total length of the VHF radiation sources propagation, and estimated velocity were 10.2 +/- 0.3 km, 2.9 +/- 0.6 km, and 1.8 x 108 and 2.8 x 108 ms-1, respectively. On the other hand, interferometer map for an NBE that initiated a single-stroke CG (NBE3) showed bidirectional fast streamers propagation with initiation altitude, total length of the VHF radiation sources propagation, and estimated velocity were 14.0 +/- 0.4 km, 2.9 +/- 0.82 km, and 1.6 x 108 and 2.8 x 108 ms-1, respectively. Clearly, the microwave and VHF radiation pulses associated with positive NBEs have been emitted by different processes of fast breakdown mechanism. Therefore, it can be suggested that the microwave radiation is emitted by electron avalanches/corona while the VHF ra-diation is emitted by fast propagating streamers.
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| 31. |
- Baharin, Shamsul Ammar Shamsul, et al.
(författare)
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Microwave radiation associated with stepped leaders of negative cloud-to-ground flashes
- 2022
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Ingår i: Atmospheric research. - : Elsevier. - 0169-8095 .- 1873-2895. ; 270
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, Very-High Frequency (VHF) and microwave radiation pulses associated with stepped leader pulses (conventional breakdown) are examined. A total of 100 stepped leader pulses (SLPs) with the associated 100 quiet periods (QPs) from ten negative cloud-to-ground (CG) flashes within the reversal distance (<8 km) have been analyzed. The QP is defined as the period between two SLPs when no electrical activity within the fast antenna sensor bandwidth was detected. The measurement system is made up of fast antenna (FA) and slow antenna (SA) sensors, a VHF sensor (60 MHz center frequency with 40 MHz bandwidth), and a microwave sensor (0.97 GHz center frequency with 20 MHz bandwidth). The waveforms were sampled at 2.5 GHz (400 ps). The total durations of the SLPs and QPs were 2.648 +/- 1.152 mu s and 2.708 +/- 1.670 mu s, respectively. All microwave and VHF radiation waveforms have been detected as clear individual oscillating pulses. The key finding is that the microwave radiation can be classified into three categories based on the total number of detected individual oscillating pulses during the QP. Two microwave pulses detected during the QP (Category 1) are suggested to be associated with the electron avalanche/corona process at the tip of an existing negative leader and a space stem. The VHF pulses associated with the microwave pulses are suggested to be emitted by propagating streamers. On the other hand, a single microwave pulse detected during the QP (Category 2) is suggested to be emitted by the electron avalanche/corona process of a space stem. The VHF pulses associated with the microwave pulse are suggested to be emitted by propagating streamers. In both categories, 70% of the microwave radiation pulses have been observed to precede VHF radiation pulses with an average lead time of 0.848 +/- 1.336 mu s. The head-on collision of a downward propagating negative streamer and an upward propagating positive streamer (from space stem) emitted significant microwave radiation. A new negative leader was formed when the head-on collision took place. The microwave radiation pulses emitted by the head-on collision process were observed to precede SLPs with an average lead time of 0.423 +/- 0.378 mu s. Around 80% of the microwave radiation pulses preceded VHF radiation pulses with average lead time of 0.540 +/- 0.596 mu s. Therefore, microwave and VHF radiation pulses are suggested to be emitted by different processes of the electrical breakdown mechanism. The microwave radiation is emitted by electron avalanche/corona/head-on collision while the VHF radiation is emitted by propagating streamers.
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| 32. |
- Baharin, Shamsul Ammar Shamsul, et al.
(författare)
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Very high frequency radiation emitted by negative narrow bipolar events occurred over malacca strait
- 2024
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier. - 1364-6826 .- 1879-1824. ; 259
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, Very -High Frequency (VHF) radiation pulses associated with 11 negative Narrow Bipolar Events (NBEs) produced by a tropical storm over Malacca Strait are examined. The lightning data were recorded from a measurement station (ST) which consisted of a fast antenna (FA) and three VHF sensors (two 5 m perpendicular baselines interferometer). The average rise time (RT), average zero -crossing time (ZCT), average pulse duration (PD), and range of peak currents of the negative NBEs were 1.4 +/- 0.4 mu s, 2.7 +/- 1.0 mu s, 12.0 +/- 6.9 mu s, and -10 to -64 kA, respectively. The key finding is that all VHF radiation pulses have been found to precede the negative NBEs with an average lead time of 0.7 +/- 0.3 mu s. An interferometer map for one negative NBE (labelled as NBE10) detected at 35.7 km from ST has shown a characteristic of mixed propagation direction of fast streamers. The first VHF radiation source was detected at 12.4 +/- 0.4 km above sea level. The total length and estimated velocity of the main propagation of the VHF radiation sources were 2.2 +/- 0.7 km and between 1.4 x 10 8 and 2.8 x 10 8 ms -1 , respectively. Moreover, based on the Himawari satellite image, the maximum extent of the cloud top height was estimated to be around 20.9 km over sea level (over Malacca Strait). All the VHF radiation sources associated with NBE10 were suggested to be detected above the main negative charge region (6 km altitude that corresponds to -10 degrees C). Thus, it could be suggested that NBE10 was initiated most likely in the environment of the ice crystals alone, based on the first altitude of the VHF radiation source and maximum extent of cloud top height.
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| 33. |
- Mohammad, Sulaiman Ali, et al.
(författare)
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Characteristics of Lightning Electromagnetic Fields Produced by Antarctica Storms
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the temporal characteristics of electromagnetic fields produced by cloud-to-ground (CG) lightning flashes associated with Antarctica storms. A total of 51 positive CG (+CG) and 103 negative CG (-CG) flashes have been recorded by a magnetic direction finder (MDF) sensor in King Sejong Station, King George Island. In total, 47 positive and 107 negative return strokes were located, ranges from 32 to 569 km. All CG flashes were detected to occur over the ocean. The return strokes characteristics include the observations of slow front, fast rising, rise time, and pulse duration with geometric mean values of 3.2, 0.53, 3.21, 13.12, and 67.09 mu s for +CG flashes, while 3.9, 0.57, 3.72, 20.75, and 69.86 mu s for -CG flashes, respectively. Additionally, the average peak currents of +CG and -CG flashes were 4.13 kA and 3.14 kA, respectively. The temporal characteristics of the return strokes of Antarctica storms are comparable to other geographical regions. The smaller peak currents might be due to small magnitude of Antarctica cloud charges when compared to other geographical regions.
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| 34. |
- Mohammad, Sulaiman Ali, et al.
(författare)
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Observation of Lightning Occurrence Surrounding Antarctica Peninsula
- 2021
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Ingår i: 2021 35TH INTERNATIONAL CONFERENCE ON LIGHTNING PROTECTION (ICLP) AND XVI INTERNATIONAL SYMPOSIUM ON LIGHTNING PROTECTION (SIPDA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665423465
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Konferensbidrag (refereegranskat)abstract
- In this study, we present the observation of cloud-to-ground (CG) flashes detected surrounding Antarctica Peninsula. Lightning sensors had been setup and deployed at King Sejong station in King George Island, Antarctica Peninsula. The lightning sensors consist of fast and slow electric field sensors that uses parallel plate antenna accompanied with respective buffer circuits. A magnetic field sensor was also deployed with two orthogonal loops antennas. The lightning data were collected between 11th and 31st January 2020. 20 storms have been identified with a total of 176 CG flashes detected. From the total CG, 116 were identified as negative CG flashes while 60 were identified as positive CG flashes.
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| 35. |
- Sabri, Muhammad Haziq Mohammad, et al.
(författare)
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Microwave Radiation Associated with Lightning Initiation Events of Negative Cloud-to-Ground Flashes
- 2022
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Ingår i: Atmosphere. - : MDPI. - 2073-4433. ; 13:9
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examined the initiation events of ten negative cloud-to-ground (CG) flashes detected close to measurement stations on 12 November (CG-1 to CG-5) and 24 November (CG-6 to CG-10), 2019. All CG flashes were accompanied by microwave and very-high frequency (VHF) radiation pulses. We recorded all the CG flashes from two measurement stations (ST1 and ST2), which are separated by 13.3 km and consist of fast and slow antenna (FA and SA) sensors, a magnetic field (B-field) sensor, a VHF sensor (60 MHz), and a microwave sensor (similar to 1 GHz). The key finding is that all of the microwave radiation pulses detected before the onset of initial electric field changes (IECs) preceded all VHF radiation pulses with an average lead time of 1.53 mu s, ranging between 0.3 and 3.0 mu s (for all CG flashes within reversal distance). A total of 50%, 17%, and 33% CG flashes were initiated by a single radiation pulse, two radiation pulses, and three radiation pulses, respectively, and were followed by IECs. Some VHF pulses are classified as short VHF radiation pulses (pulse duration less than 0.5 mu s). The average duration from the first microwave and VHF pulses to the onset of IECs were 53.4 mu s and 32.78 mu s, respectively. The VHF radiation pulses detected before the IECs are suggested to be emitted by short-length positive streamers. Because the microwave radiation pulses were detected earlier (average lead time of 1.53 mu s) than VHF radiation pulses, it is most likely that the microwave pulses were emitted by an electron avalanche process.
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