Characteristics of recoil leaders as observed by LOFAR

Stijn Buitink, Olaf Scholten, Brian M. Hare, S. ter Veen, J. R. Dwyer, Ningyu Liu, C. Sterpka, S. ter Veen

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Abstract

Lightning dart leaders and recoil leaders are current pulses that propagate along previously established
lightning channels reionizing the channel. They are poorly understood since it is not known how a
previously ionized channel can undergo dielectric breakdown multiple times. In this work we investigate
five recoil leaders on two different channels using lightning observations of the LOFAR radio telescope in
vhf (where we observe 30–80 MHz) using our TRI-D interferometric imaging algorithm. We show that
while recoil leaders do slow down over time on average, they can also clearly accelerate. In addition, the vhf
power emitted by the recoil leader is closely correlated with speed. We also investigate the vhf-emitting
width of the recoil leaders and show that it is thinner than our meter-scale resolution. This shows that recoil
leaders have significant streamer activity in their channel core or at most very inner region of the corona
sheath, and that there is either very little, or weakly vhf-emitting, streamer activity in the majority of the
corona sheath. Finally, we show that recoil leaders can have small microsecond-scale fluctuations in
emitted vhf power that can occur in the same spot across subsequent recoil leaders on the same channel,
demonstrating that recoil leader propagation is affected by small-scale channel geometry.
Original languageEnglish
Article number023025
Number of pages15
JournalPhysical Review D
Volume107
Issue number2
DOIs
Publication statusPublished - 31 Jan 2023

Bibliographical note

Funding Information:
The LOFAR cosmic-ray key science project acknowledges funding from an Advanced Grant of the European Research Council (Grant No. FP/2007-2013)/ERC Grant Agreement No. 227610. The project has also received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 640130). B. M. H. is supported by NWO (VI.VENI.192.071) and ERC Grant Agreement No. 101041097. LOFAR, the Low Frequency Array designed and constructed by ASTRON, has facilities in several countries that are owned by various parties (each with their own funding sources), and that are collectively operated by the International LOFAR Telescope foundation under a joint scientific policy.

Publisher Copyright:
© 2023 American Physical Society.

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