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Title: Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also subrelativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler mode wave-particle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Tromsø VHF radar on 17 November 2012. Electron density enhancements were clearly identified at altitudes >68 km in association with the pulsating aurora, suggesting precipitation of electrons with a broadband energy range from ~10 keV up to at least 200 keV. The riometer and network of subionospheric radio wave observations also showed the energetic electron precipitations during this period. During this period, the footprint of the Van Allen Probe-A satellite was very close to Tromsø and the satellite observed rising tone emissions of the lower band chorus (LBC) waves near the equatorial plane. Considering the observed LBC waves and electrons, we conducted a computer simulation of the wave-particle interactions. This showed simultaneous precipitation of electrons at both tens of keV and a few hundred keV, which is consistent with the energy spectrum estimated by the inversion method using the EISCAT observations. This resultmore » revealed that electrons with a wide energy range simultaneously precipitate into the ionosphere in association with the pulsating aurora, providing the evidence that pulsating auroras are caused by whistler chorus waves. We suggest that scattering by propagating whistler simultaneously causes both the precipitations of subrelativistic electrons and the pulsating aurora.« less
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12]
  1. Nagoya Univ., Nagoya (Japan). Solar-Terrestrial Environment Lab.
  2. Nagoya Univ., Nagoya (Japan). Graduate School of Science.
  3. Seikei Univ., Musashino (Japan). Faculty of Science and Technology.
  4. National Institute of Polar Research, Tachikawa (Japan)
  5. Kyoto Univ., Uji (Japan). Research Institute for Sustainable Humanosphere.
  6. Univ. of Iowa, Iowa City, IA (United States)
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  8. Institute of Atmospheric Physics CAS, Prague (Czech Republic). Dept. of Space Physics; Charles Univ. in Prague, Prague (Czech Republic). Faculty of Mathematics and Physics.
  9. British Antarctic Survey, Cambridge (United Kingdom)
  10. Univ. of Otago, Dunedin (New Zealand). Dept. of Physics.
  11. Univ. of Oulu, Oulu (Finland). Sodankyla Geophysical Observatory.
  12. Tohoku Univ., Sendai (Japan). Planetary Plasma and Atmospheric Research Center.
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 4; Journal ID: ISSN 2169-9380
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States