Japan Geoscience Union Meeting 2018

Presentation information

[EE] Poster

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

[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

Tue. May 22, 2018 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Danny Summers(Memorial University of Newfoundland), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Keisuke Hosokawa(電気通信大学大学院情報理工学研究科, 共同), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University)

[PEM16-P15] Oxygen torus near the plasmapause observed by Arase

*Masahito Nose1, Ayako Matsuoka2, Atsushi Kumamoto3, Yoshiya Kasahara4, Mariko Teramoto5, Fuminori Tsuchiya3, Shoya Matsuda5, Masafumi Shoji5, Yuki Obana6, Shun Imajo1, Oimatsu Satoshi1, Kazuhiro Yamamoto1, Reiko Nomura7, Akiko Fujimoto8, Iku Shinohara2, Yoshizumi Miyoshi5 (1.Graduate School of Science, Kyoto University, 2.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3.Graduate School of Science, Tohoku University, 4.Information Media Center, Kanazawa University, 5.Institute for Space-Earth Environmental Research, Nagoya University, 6.Faculty of Engineering, Osaka Electro-Communication University, 7.Tsukuba Space Center, Japan Aerospace Exploration Agency, 8.International Center for Space Weather Science and Education, Kyusyu University)

Using the magnetic field and plasma wave data obtained by the fluxgate magnetometer (MGF) and plasma wave experiment/high-frequency wave receiver and onboard frequency analyzer (PWE/HFA and OFA) instruments on board the Arase satellite, we search for enhancements of O+ ion density in the deep inner magnetosphere known as “the oxygen torus”. We estimate the local plasma mass density (rhoL) and the local electron number density (neL) from the resonant frequencies of standing Alfvén waves and the upper hybrid resonance band, respectively. The average ion mass (M) can be calculated by M~rhoL/neL under the assumption of quasi-neutrality of plasma. Preliminary analysis of some events at dawn, in which toroidal standing Alfvén waves appear clearly during the storm recovery phase, reveals that M is enhanced in the vicinity of the plasmapause, implying formation of the oxygen torus. In presentation, we will show more detailed analysis results and discuss the formation mechanism of the oxygen torus.