Post-return stroke VHF electromagnetic activity in north-western Mediterranean cloud-to-ground lightning flashes
<p>We investigate properties of the electromagnetic activity following the first lightning return stroke (RS), using concurrent observations from the SLAVIA (Shielded Loop Antenna with a Versatile Integrated Amplifier) sensor, the SAETTA (Suivi de l'Activité Electrique Tridimensionnelle T...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/1791/2025/acp-25-1791-2025.pdf |
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| Summary: | <p>We investigate properties of the electromagnetic activity following the first lightning return stroke (RS), using concurrent observations from the SLAVIA (Shielded Loop Antenna with a Versatile Integrated Amplifier) sensor, the SAETTA (Suivi de l'Activité Electrique Tridimensionnelle Totale de l'Atmosphère) Lightning Mapping Array (LMA) and the METEORAGE LF (low-frequency) network in the Corsica region. From the data collected between September and December 2015, we selected 66 negative cloud-to-ground (<span class="inline-formula">−CG</span>) and 26 positive cloud-to-ground (<span class="inline-formula">+CG</span>) lightning flashes in the north-western Mediterranean region. In the SAETTA data, we observe a decrease in the very high frequency (VHF) radiation rate and the VHF power, as recorded within a typical 80 <span class="inline-formula">µs</span> time window at the LMA stations, immediately after the RS pulse in 59 <span class="inline-formula">−CG</span> flashes. Contrastingly, we show that all examined <span class="inline-formula">+CG</span> flashes exhibit a rapid increase in the VHF radiation rate and the VHF power immediately after the RS. We suggest a possible explanation of this phenomenon by considering the step-like propagation of a negative part of the bidirectional leader starting at the top end of the positive lightning channel inside the thundercloud, emitting electromagnetic radiation across a broad frequency spectrum.</p> |
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| ISSN: | 1680-7316 1680-7324 |