Lightning initiation: Strong pulses of VHF radiation accompany preliminary breakdown

0487518 - ÚFA 2018 RIV GB eng J - Journal Article
Kolmašová, Ivana - Santolík, Ondřej - Defer, E. - Rison, W. - Coquillat, S. - Pedeboy, S. - Lán, Radek - Uhlíř, Luděk - Lambert, D. - Pinty, J.P. - Prieur, S. - Pont, V.
Lightning initiation: Strong pulses of VHF radiation accompany preliminary breakdown.
Scientific Reports. Roč. 8, č. 1 (2018), č. článku 3650. ISSN 2045-2322. E-ISSN 2045-2322
R&D Projects: GA ČR GA17-07027S
Grant - others:AV ČR(CZ) AP1401
Program: Akademická prémie - Praemium Academiae
Institutional support: RVO:68378289
Keywords : controlled study * article * electromagnetic radiation * magnetic field * waveform * lightning * mapping array * discharges * ionosphere * luminosity * flashes * leaders * system
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 4.011, year: 2018
https://www.nature.com/articles/s41598-018-21972-z

We analyze lightning initiation process using magnetic field waveforms of preliminary breakdown (PB) pulses observed at time scales of a few tens of microseconds by a broad-band receiver. We compare these pulses with sources of narrow-band very high frequency (VHF) radiation at 60–66 MHz recorded by two separate Lightning Mapping Arrays (LMAs). We find that almost none of the observed PB pulses correspond to geo-located VHF radiation sources, in agreement with previous results and with the hypothesis that processes generating VHF radiation and PB pulses are only weakly related. However, our detailed analysis discovers that individual peaks of strong VHF radiation seen by separate LMA stations correspond surprisingly well to the PB pulses. This result shows that electromagnetic radiation generated during fast stepwise extension of developing lightning channels is spread over a large interval of frequencies. We also show that intense VHF radiation abruptly starts with the first PB pulse and that it is then continuously present during the entire PB phase of developing discharges.
Permanent Link: http://hdl.handle.net/11104/0282233