Japan Geoscience Union Meeting 2015

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International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM09] Dynamics in magnetosphere and ionosphere

Wed. May 27, 2015 11:00 AM - 12:45 PM 302 (3F)

Convener:*Shin'ya Nakano(The Institute of Statistical Mathematics), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Hiroshi Hasegawa(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Nagoya University Solar Terrestrial Environment Laboratory Geospace Research Center), Chair:Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University)

11:30 AM - 11:45 AM

[PEM09-03] Cusp aurora as a backward-elongated image of the moving region of electron precipitation

*Satoshi TAGUCHI1, Yasunaga CHIBA2, Keisuke HOSOKAWA2, Yasunobu OGAWA3 (1.Graduate School of Science, Kyoto Univ., 2.Graduate School of Informatics and Engineering, Univ. of Electro-Communications, 3.National Institute of Polar Research)

Keywords:aurora, cusp, plasma flow, electron precipitation, electron temperature, ion temperature

We present high time resolution observations of the red-line moving cusp aurora made on 27 November 2011 by an all-sky imager at Longyearbyen, Svalbard, and their comparison with EISCAT observations. The EISCAT radar pointing in the magnetic field-aligned direction detected several enhancements of electron temperatures whose durations are 1-5 min. The all-sky imager data obtained with a time resolution of 4 s allowed us to determine a one-to-one correspondence between electron temperature enhancements and cusp aurora intensifications. The radar beam entered the moving cusp aurora structure from its forward side, and exited from the backward side in some events, while in others the beam skimmed the moving aurora. Further analyses of the former events revealed that the enhancement of the electron temperature, which was produced by the intense electron precipitation, terminated 60-90 s earlier than the exit of the radar's field-of-view from the moving aurora. This duration is consistent with the lifetime of the O(1D) state. Our observation provides evidence demonstrating that the cusp aurora is a backward-elongated image of the moving region of electron precipitation. The enhancement of ion temperature was also found to be in the moving cusp aurora structure. On the basis of these results we discuss the spatial relationship between electron precipitation and fast plasma flow, which causes the ion temperature enhancement.