University of Oulu

Kolmašová, I., Santolík, O., Kašpar, P., Popek, M., Pizzuti, A., Spurný, P., et al. (2021). First observations of elves and their causative very strong lightning discharges in an unusual small‐scale continental spring‐time thunderstorm. Journal of Geophysical Research: Atmospheres, 126, e2020JD032825. https://doi.org/10.1029/2020JD032825

First observations of elves and their causative very strong lightning discharges in an unusual small‐scale continental spring‐time thunderstorm

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Author: Kolmašová, Ivana1,2; Santolík, Ondřej1,2; Kašpar, Petr1;
Organizations: 1Department of Space Physics, Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czech Republic
2Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
3Department of Electronic and Electrical Engineering, University of Bath, Bath, UK
4Bristol Industrial and Research Associates Limited, Bristol, UK,
5Interplanetary Matter Department, Astronomical Institute, Czech Academy of Sciences, Ondrejov, Czech Republic
6Department of Electronics, AGH University of Science and Technology, Krakow, Poland
7Sodankylä Geophysical Observatory, Sodankylä, Finland
8Department of Meteorology, Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czech Republic
9Department of ALDIS, OVE Service GmbH, Vienna, Austria
10Bristol Industrial and Research Associates Limited, Bristol, UK
11SOSA (Slovak Organization for Space Activities), Bratislava, Slovakia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 6.8 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe202102043719
Language: English
Published: American Geophysical Union, 2021
Publish Date: 2021-06-04
Description:

Abstract

We show for the first time that elves can be produced by an unusual small‐scale continental spring‐time thunderstorm. The storm occurred in Central Europe, covered a very small area of ∼50 × ∼30 km and lasted only for ∼4 h on April 2, 2017. The fraction of intense positive cloud‐to‐ground lightning strokes was unusually high, reaching 55%, with a mean peak current of 64 kA. The peak currents of return strokes (RS) associated with elves exceeded ∼300 kA. Elves and their causative RS have been observed with different optical and electromagnetic recordings. Signatures of ionospheric disturbances indicating the presence of elves were found in measurements of displacement currents, ionospheric reflections of sferics and man‐made narrow‐band transmissions. All these electromagnetic observations coincide with four optical detections of elves and strongly suggest the occurrence of two more elves later in the decaying phase of the storm. Surprisingly, the same electromagnetic measurements indicate that other strong strokes did not produce any elves. Our simulation results show that the formation of an elve is not only determined by the high‐peak current of their causative strokes but that it is also controlled by the conductivity of the lightning channels and velocity of the current wavefront. We hypothesize that because of a lower conductivity of RS lightning channels and/or slower current waves only very strong strokes with peak currents above ∼300 kA might have been capable to produce observable elves during this thunderstorm.

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Series: Journal of geophysical research. Atmospheres
ISSN: 2169-897X
ISSN-E: 2169-8996
ISSN-L: 2169-897X
Volume: 126
Issue: 1
Article number: e2020JD032825
DOI: 10.1029/2020JD032825
OADOI: https://oadoi.org/10.1029/2020JD032825
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
111 Mathematics
1172 Environmental sciences
Subjects:
Funding: The work of I. Kolmašová and O. Santolík was supported by European Regional Development Fund‐Project CRREAT (CZ.02.1.01/0.0/0.0/15_003/0000481) and by the Praemium Academiae award of the Czech Academy of Sciences. The work of P. Kašpar, M. Popek, R. Lán, and L. Uhlíř was supported by the GACR grant 20‐09671S. Similarly, another Preamium Academiae award of the CAS supported the work of P. Spurný and J. Borovička. The above listed authors thanks the Strategy AV21 of the Czech Academy of Sciences for valuable support. The National Science Center, Poland, under grant 2015/19/B/ST10/01055, supported the work of J. Mlynarczyk. We thank Laboratoire Souterrain à Bas Bruit, UNS/UAPV/CNRS, Rustrel, France, and its Director S. Gaffet, for hosting our VLF receiving station at their facility at La Grande Montagne.
Dataset Reference: All other data are available at http://dx.doi.org/10.17632/z5y3ggw6gm.1. Rustrel VLF data are available at http://bleska.ufa.cas.cz/lsbb/storage/elm/.
  http://dx.doi.org/10.17632/z5y3ggw6gm.1
http://bleska.ufa.cas.cz/lsbb/storage/elm/
Copyright information: © 2020. American Geophysical Union. All Rights Reserved.