SM14C-02
Wide energy electron precipitations and their impact on the middle atmosphere associated with the pulsating aurora
Monday, 14 December 2015: 16:12
2018 (Moscone West)
Yoshizumi Miyoshi1, Shin-ichiro Oyama2, Shinji Saito2, Esa S Turunen3, Satoshi Kurita2, Antti Kero4, Pekka T Verronen5, Ryuho Kataoka6, Yusuke Ebihara7, Craig Kletzing8, Geoffrey D Reeves9, Ondrej Santolik10, Mark A. Clilverd11, Craig J Rodger12 and Fuminori Tsuchiya13, (1)STEL, Nagoya University, Nagoya, Japan, (2)Nagoya University, Nagoya, Japan, (3)University Oulu, Sodankyla, Finland, (4)Sodankyla Geophysical Observatory, Sodankyla, Finland, (5)Finnish Meteorological Institute, Helsinki, Finland, (6)National Institute of Polar Research, Tachikawa, Japan, (7)Kyoto University, Kyoto, Japan, (8)University of Iowa, Iowa City, IA, United States, (9)Los Alamos National Laboratory, Los Alamos, NM, United States, (10)Institute of Atmospheric Physics ACSR, Praha 4, Czech Republic, (11)British Antarctic Survey, Cambridge, United Kingdom, (12)University of Otago, Dunedin, New Zealand, (13)Tohoku University, Sendai, Japan
Abstract:
The pulsating aurora is caused by intermittent precipitations of tens keV electrons. It is also expected that not only tens keV electrons but also sub-relativistic/relativistic electrons precipitate simultaneously into the polar ionosphere owing to whistler-mode wave-particle interactions. We analyzed a pulsating aurora event in November 2012 using several ground-based observation data from EISCAT radar, riometer, sub-ionospheric radio wave receivers, and the Van Allen Probes satellite. The electron density profile obtained from EISCA Tromsø VHF radar identifies electron density enhancements at >68 km altitudes. The electron energy spectrum derived from the Markov Chain Monte Carlo (MCMC) method indicates the wide energy electron precipitations from 10 - 200 keV, suggesting precipitation of the population from the outer belt. The riometer and network of sub-ionospheric radio wave observations also show energetic electron precipitations coinciding with the electron density enhancements at 68 km altitude. During this period, 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. Using the satellite-observed LBC and trapped electrons as an initial condition, we conducted a computer simulation of the wave-particle interactions. The simulation showed simultaneous precipitation of electrons at both tens of keV and a few hundred keV. This result is consistent with the energy spectrum estimated with the MCMC method. This result revealed that electrons with a wide energy range from the plasma sheet to the outer belt simultaneously precipitate into the polar ionosphere in association with the pulsating aurora. Using the Sodankylä Ion Chemistry (SIC) model that is a detailed coupled neutral and ion chemistry model of the upper atmosphere, we also discuss the possible impacts on the middle atmosphere due to precipitations of wide energy electrons.
