Japan Geoscience Union Meeting 2018

Presentation information

[EE] Poster

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

[P-EM15] Dynamics in magnetosphere and ionosphere

Mon. May 21, 2018 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Institute for Space-Earth Environmental Research, Nagoya University), Aoi Nakamizo(情報通信研究機構 電磁波研究所, 共同), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University)

[PEM15-P11] Relation between auroral luminosity Pc 5 oscillations and Poynting flux of ULF wave Pc 5 oscillations

*Tohru Sakurai1, Natsuo Sato2, Akira Kadokura2, Yoshimasa Tanaka2 (1.Tokai University, 2.National Institute Polar Research)

Keywords:Aurora, Pc 5 oscillation, Substorm, Field line resonance

It is well known that optical Pc 5 oscillations in aurora are frequently observed during a recovery phase of a substorm. In this paper we try to examine how much energy can Poynting flux of ULF wave Pc 5 oscillations generate in the magnetotail and whether is it enough to excite aurorae at the ionospheric altitude or not? Data used in this study are simultaneous measurements on the ground with all sky imagers from the Time History Events and Macroscale Interactions during Substorm (THEMIS) Ground Based Observatories (GBOs) and in situ with the THEMIS satellites, -A, -D and -E traversed in the early morning side plasma sheet. The result is as follows; Poynting flux calculated by using electric and magnetic field perturbations of typical Pc 5 oscillations observed in the plasma sheet near the magnetic equator is a value of 5~10 micro Watt/m^2, which corresponds to 10 ~ 20 mW/m^2 at the ionospheric altitude. This value is revealed to be about 10 times of the least energy ~ 1 mW/m^2 for the excitation of aurora at the ionospheric height. Therefore, we can suppose that Pc 5 field-line resonant oscillations have an energy enough to produce auroral luminosity oscillations in the ionosphere. In addition auroral luminosity Pc 5 oscillations are clearly seen in the limited periods, not continuously, which occur corresponding to isolated enhancement of Poynting flux of Pc 5 oscillations in the magnetotail. This observation supports the idea that Poynting flux energy of Pc 5 oscillations seem to be deeply related to auroral luminosity oscillations.