Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions

We present lightning-induced ionospheric perturbations in narrowband very-low-frequency (VLF) signals from the transmitters NWC (21.82° S, 114.17° E, 19.8 kHz) and VTX (8.4° N, 77.8° E, 18.6 kHz) recorded at the low-latitude station Dehradun (DDN; 30.3° N, 78.0° E) over a 12-month period from Septem...

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Main Authors: Dayanand Bhaskar, Rajat Tripathi, Mahesh N. Shrivastava, Rajesh Singh, Sudipta Sasmal, Abhirup Datta, Ajeet Kumar Maurya
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/16/7/832
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author Dayanand Bhaskar
Rajat Tripathi
Mahesh N. Shrivastava
Rajesh Singh
Sudipta Sasmal
Abhirup Datta
Ajeet Kumar Maurya
author_facet Dayanand Bhaskar
Rajat Tripathi
Mahesh N. Shrivastava
Rajesh Singh
Sudipta Sasmal
Abhirup Datta
Ajeet Kumar Maurya
author_sort Dayanand Bhaskar
collection DOAJ
description We present lightning-induced ionospheric perturbations in narrowband very-low-frequency (VLF) signals from the transmitters NWC (21.82° S, 114.17° E, 19.8 kHz) and VTX (8.4° N, 77.8° E, 18.6 kHz) recorded at the low-latitude station Dehradun (DDN; 30.3° N, 78.0° E) over a 12-month period from September 2020 to October 2021. Early/slow VLF events, VLF LOREs, and step-like VLF LOREs associated with lightning were analyzed for their onset and recovery times. This study utilized data from the World Wide Lightning Location Network (WWLLN), which provides lightning locations and energy estimates. The results show that early/slow VLF events occur most frequently, accounting for approximately 68% of cases, followed by VLF LOREs at 12%, and step-like VLF LOREs at 10%. Furthermore, we observed that 100% of the VLF perturbing events occurred during the nighttime, which is not entirely consistent with previous studies. Moreover, more than 60% of VLF LOREs were associated with lightning energies of approximately 1 kJ, and about 40% were associated with lightning energies of ~10 kJ. Step-like VLF LOREs were linked to WWLLN energies between 1 and 5 kJ. The observed WWLLN energy range is somewhat lower than the energies reported in previous studies. Scattering characteristics revealed that 87.3% of events were associated with wide-angle scattering, while approximately 12.6% were linked to narrow-angle scattering. LWPC version 2.1 was used to simulate these perturbing events and to estimate the reflection height (H′, in km) and the exponential sharpness factor (β, in km<sup>−1</sup>) corresponding to changes in D-region electron density. The reflection height (H′, in km) and the exponential sharpness factor (β, in km<sup>−1</sup>) of the D-region varied from 83 to 87 km and from 0.42 to 0.79 km<sup>−1</sup> for early/slow VLF events, from 83 to 85 km and from 0.5 to 0.75 km<sup>−1</sup> for step-like VLF LOREs, and from 81 to 83 km and from 0.75 to 0.81 km<sup>−1</sup> for VLF LOREs, respectively.
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spelling doaj-art-11458eed688e4a6bb3e49f1fe77e75a62025-08-20T03:13:39ZengMDPI AGAtmosphere2073-44332025-07-0116783210.3390/atmos16070832Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial RegionsDayanand Bhaskar0Rajat Tripathi1Mahesh N. Shrivastava2Rajesh Singh3Sudipta Sasmal4Abhirup Datta5Ajeet Kumar Maurya6Department of Physics, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, IndiaDepartment of Physics, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, IndiaDepartment of Geosciences, Universidad Católica del Norte (UCN), Av. Angamos 0610, Antofagasta 1270709, ChileKSK Geomagnetic Research Laboratory, Indian Institute of Geomagnetism, Prayagraj 221505, IndiaInstitute of Astronomy Space and Earth Science, P177, CIT Road, Kolkata 700054, IndiaDepartment of Astronomy, Astrophysics and Space Engineering, Indian Institute of Technology Indore, Indore 453552, IndiaDepartment of Physics, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow 226025, IndiaWe present lightning-induced ionospheric perturbations in narrowband very-low-frequency (VLF) signals from the transmitters NWC (21.82° S, 114.17° E, 19.8 kHz) and VTX (8.4° N, 77.8° E, 18.6 kHz) recorded at the low-latitude station Dehradun (DDN; 30.3° N, 78.0° E) over a 12-month period from September 2020 to October 2021. Early/slow VLF events, VLF LOREs, and step-like VLF LOREs associated with lightning were analyzed for their onset and recovery times. This study utilized data from the World Wide Lightning Location Network (WWLLN), which provides lightning locations and energy estimates. The results show that early/slow VLF events occur most frequently, accounting for approximately 68% of cases, followed by VLF LOREs at 12%, and step-like VLF LOREs at 10%. Furthermore, we observed that 100% of the VLF perturbing events occurred during the nighttime, which is not entirely consistent with previous studies. Moreover, more than 60% of VLF LOREs were associated with lightning energies of approximately 1 kJ, and about 40% were associated with lightning energies of ~10 kJ. Step-like VLF LOREs were linked to WWLLN energies between 1 and 5 kJ. The observed WWLLN energy range is somewhat lower than the energies reported in previous studies. Scattering characteristics revealed that 87.3% of events were associated with wide-angle scattering, while approximately 12.6% were linked to narrow-angle scattering. LWPC version 2.1 was used to simulate these perturbing events and to estimate the reflection height (H′, in km) and the exponential sharpness factor (β, in km<sup>−1</sup>) corresponding to changes in D-region electron density. The reflection height (H′, in km) and the exponential sharpness factor (β, in km<sup>−1</sup>) of the D-region varied from 83 to 87 km and from 0.42 to 0.79 km<sup>−1</sup> for early/slow VLF events, from 83 to 85 km and from 0.5 to 0.75 km<sup>−1</sup> for step-like VLF LOREs, and from 81 to 83 km and from 0.75 to 0.81 km<sup>−1</sup> for VLF LOREs, respectively.https://www.mdpi.com/2073-4433/16/7/832D-regionVLF scatteringwave propagationlightningLOREearly/slow
spellingShingle Dayanand Bhaskar
Rajat Tripathi
Mahesh N. Shrivastava
Rajesh Singh
Sudipta Sasmal
Abhirup Datta
Ajeet Kumar Maurya
Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
Atmosphere
D-region
VLF scattering
wave propagation
lightning
LORE
early/slow
title Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
title_full Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
title_fullStr Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
title_full_unstemmed Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
title_short Lower Ionospheric Perturbations Associated with Lightning Activity over Low and Equatorial Regions
title_sort lower ionospheric perturbations associated with lightning activity over low and equatorial regions
topic D-region
VLF scattering
wave propagation
lightning
LORE
early/slow
url https://www.mdpi.com/2073-4433/16/7/832
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AT rajeshsingh lowerionosphericperturbationsassociatedwithlightningactivityoverlowandequatorialregions
AT sudiptasasmal lowerionosphericperturbationsassociatedwithlightningactivityoverlowandequatorialregions
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