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Observations of elves and radio wave perturbations by lightning
  • +5
  • Maja Tomicic,
  • Olivier Chanrion,
  • Thomas Farges,
  • Janusz Mlynarczyk,
  • Ivana Kolmasová,
  • Serge Soula,
  • Christoph Köhn,
  • Torsten Neubert
Maja Tomicic
DTU Space, Technical University of Denmark

Corresponding Author:majtom@space.dtu.dk

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Olivier Chanrion
National Space Institute (DTU Space)
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Thomas Farges
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Janusz Mlynarczyk
AGH University of Science and Technology
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Ivana Kolmasová
Department of Space Physics, Institute of Atmospheric Physics, Czech Academy of Sciences
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Serge Soula
Laboratoire d'Aerologie
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Christoph Köhn
Technical University of Denmark
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Torsten Neubert
Department of Solar System Physics, Denmark
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The electromagnetic and electrostatic fields from powerful lightning heat and ionize the lower ionosphere. The disturbances appear as halos, sprites and elves, and are also observed as perturbations in crossing radio signals. The characteristic of the lightning discharges leading to the various types of perturbations is not fully understood. Here we present an analysis of 63 elves and corresponding VLF and MF signal perturbations from an almost stationary thunderstorm that allows us to untangle some of the dependencies of perturbations on the lightning characteristics. We characterize the perturbations to a VLF-transmitter signal as “long-recovery-early-events” (LOREs), “early” events, or “rapid-onset-rapid-decay” (RORD) events. We find that LOREs are related to high lightning current and bright elves, and their amplitude and sign depend on their location along the signal path. With observations in the ELF and MF band, we find that lightning with elves has three times the impulse charge moment change (iCMC) and ten times the power than lightning of similar peak current without elves. Attenuation in MF links appear in a higher proportion and longer duration observed with elves than with high peak current lightning without elves. The remaining types of VLF perturbations occur without TLEs but with sequences of lightning that produce slowly rising CMCs reaching high values (up to ~3500 C km within ~500 ms). Slower rise times lead to lower fields in the mesosphere that may not create significant ionization but instead drive dissociative attachment of free electrons. The depletions can result in perturbations to crossing VLF signals.