EGU23-12591
https://doi.org/10.5194/egusphere-egu23-12591
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

The propagation and 3D VHF polarization properties of recoil leaders

Brian Hare1,2, Olaf Scholten2, Stijn Buitink3, Joseph Dwyer4, Ningyu Liu4, Chris Sterpka4, and Sander ter Veen1
Brian Hare et al.
  • 1Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo, The Netherlands (b.h.hare@rug.nl)
  • 2Kaptyen Astronomical Institute, University of Groningen, Groningen, Netherlands
  • 3Astrophysical Institute, Vrije Universiteit Brussel, Brussels, Belgium
  • 4Department of Physics and Astronomy & Space Science Center (EOS), University of New Hampshire, Durham, USA

Lightning dart and recoil leaders are difficult to understand, as they have a different (often smoother) propagation mode than stepped leaders, and re-ionize a previously ionized channel. In order to understand them better, we have imaged recoil leaders with the LOFAR radio telescope (30-80 MHz), and will present 3D polarization, speed, and intensity data from multiple recoil leaders. We will show that many recoil leaders with high VHF intensity have VHF polarization that is very parallel to the recoil leader channel, with an opening angle as small as 15 degrees. Recoil leaders with lower VHF intensity have larger polarization opening angles, but it is not clear if this is physical or instrumental. In addition, VHF emission from recoil leaders comes from a sub-meter thin channel. Finally, we will show that the propagation speed and VHF intensity are strongly correlated; almost following a power-law or exponential relationship. These results probe the streamer behavior of recoil leaders, and thus provide significant clues to how recoil and dart leaders propagate. The fact that recoil leaders are very VHF thin is consistent with small polarization opening angles, and demonstrates that recoil leaders have significant streamer activity in their core and their corona sheath is VHF silent. The power-law/exponential relationship between speed and VHF intensity, however, is very difficult to explain.

How to cite: Hare, B., Scholten, O., Buitink, S., Dwyer, J., Liu, N., Sterpka, C., and ter Veen, S.: The propagation and 3D VHF polarization properties of recoil leaders, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12591, https://doi.org/10.5194/egusphere-egu23-12591, 2023.