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Lightning evolution and VLF perturbations associated with category 5 TC Yasa in the South Pacific region

Redoblado, Paolo A. A. L. and Kumar, Sarwan and Kumar, Abhikesh and Kumar, Sushil (2022) Lightning evolution and VLF perturbations associated with category 5 TC Yasa in the South Pacific region. Earth, Planets and Space, 74 (65). pp. 1-20. ISSN 1343-8832

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In this paper, we present the D-region ionospheric response during the lifespan (10–19 December 2020) of a severe category 5 tropical cyclone (TC) Yasa in the South Pacific by using the very low frequency (VLF, 3-30 kHz) signals from NPM, NLK, and JJI transmitters recorded at Suva, Fiji. Results indicate enhanced lightning and convective activity in all three regions (eyewall, inner rainbands, and outer rainbands) during the TC Yasa that are also linked to the wave sensitive zones of these transmitter-receiver great circle paths. Of the three regions, the outer rainbands showed the maximum lightning occurrence; hence convective activity. Prominent eyewall lightning was observed just before the TC started to weaken following its peak intensity. Analysis of VLF signals amplitude showed both negative and positive perturbations (amplitudes exceeding ±3σ mark) lasting for more than 2 hours with maximum change in the daytime and nighttime signal amplitudes of -4.9 dB (NPM) and -19.8 dB (NLK), respectively. The signal perturbations were wave-like, exhibiting periods of oscillations between ~2.2-5.5 hours as revealed by the Morlet wavelet analysis. Additionally, the LWPC modeling of the signal perturbations indicated a 10 km increase in the daytime D-region reference height, H, and a 12 km decrease in the nighttime D-region H during TC Yasa. The D-region density gradients (sharpness), , showed small perturbations of 0.01–0.14 km-1 from its normal values. We suggest that the observed changes to the D-region parameters are due to the enhanced convection during TC Yasa which excites atmospheric gravity waves producing traveling ionospheric disturbances to the D-region.

Item Type: Journal Article
Subjects: Q Science > QC Physics > QC676-678.6 Radio waves (Theory)
Q Science > QC Physics > QC717.6-718.8 Plasma physics. Ionized gases
Divisions: School of Information Technology, Engineering, Mathematics and Physics (STEMP)
Depositing User: Abhikesh Kumar
Date Deposited: 19 May 2022 01:12
Last Modified: 19 May 2022 01:12

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