Relativistic electron beams above thunderclouds
1University of Bath, Centre for Space and Atmospheric Research, Department of Electronic and Electrical Engineering, Bath, UK
2SciTech Solutions, Melbourne, Florida, USA
3Atmospheric, Earth and Environment Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
4Kirtland Airforce Base, USAF AFMC AFRL/RVBXP, New Mexico, USA
5National Space Institute, Technical University of Denmark, Copenhagen, Denmark
6Laboratoire d'Aérologie, Université de Toulouse, Toulouse, France.
7Department of Electrical Engineering, Universitat Politècnica de Catalunya, Terrassa, Spain
8Institute of Geophysics, Deptartment of Atmospheric Physics, Polish Academy of Sciences, Warsaw, Poland
9Passive Sensing, Met Office, Exeter, UK
10Department of Electrical Engineering, Pennsylvania State University, Pennsylvania, USA
Abstract. Non-luminous relativistic electron beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The electron beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the electron beam. One electron beam was detected without any luminous sprite occurrence which suggests that electron beams may also occur independently. Numerical simulations show that the beamed electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.