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

Y Miyoshi; S Oyama; S Saito; S Kurita; H Fujiwara; R Kataoka; Y Ebihara; C Kletzing; G Reeves; O Santolik; M Clilverd; C. J Rodger; E Turunen; F Tsuchiya

doi:10.1002/2014JA020690

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

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

Y Miyoshi, S Oyama, S Saito, S Kurita, H Fujiwara, R Kataoka, Y Ebihara, C Kletzing, G Reeves, O Santolik, …

Journal of geophysical research. Space physics, Vol.120(4), pp.2754-2766

04/2015

DOI: 10.1002/2014JA020690

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Abstract

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 result 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. Key Points Precipiation of sub‐relativisitc electrons associated with the pulsating aurora Whistler mode chorus are confirmed by Van Allen Probes Simulation reproduces the energy spectrum of the precipiating electrons

EISCAT

pitch angle scattering

pulsating aurora

Van Allen Probes

Details

Title: Subtitle: Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations
Creators: Y Miyoshi - Nagoya University
S Oyama - Nagoya University
S Saito - Nagoya University
S Kurita - Nagoya University
H Fujiwara - Seikei University
R Kataoka - National Institute of Polar Research
Y Ebihara - Kyoto University
C Kletzing - University of Iowa
G Reeves - Los Alamos National Laboratory
O Santolik - Charles University
M Clilverd - British Antarctic Survey
C. J Rodger - University of Otago
E Turunen - University of Oulu
F Tsuchiya - Tohoku University
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.120(4), pp.2754-2766
DOI: 10.1002/2014JA020690
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 13
Grant note: Japan Society for the Promotion of Science (JSPS) (23340146; 23224011; 24540478; 25302006; 08811147)) International Space Science Institute's (ISSI) International Team (G2602)
Language: English
Date published: 04/2015
Academic Unit: Physics and Astronomy
Record Identifier: 9984199686302771

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