Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

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

Mon. May 21, 2018 10:45 AM - 12:15 PM 303 (3F International Conference Hall, 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), Chairperson:Hosokawa Keisuke(The University of Electro-Communications), Miyoshi Yoshizumi(ISEE, Nagoya University)

12:00 PM - 12:15 PM

[PEM16-06] Magnetic field dipolarization and its associated ion flux variations in the deep inner magnetosphere: Arase and Michibiki-1 satellite observations

*Masahito Nose1, Ayako Matsuoka2, Satoshi Kasahara3, Shoichiro Yokota4, Mariko Teramoto5, Kunihiro Keika3, Reiko Nomura6, Akiko Fujimoto7, Nana Higashio6, Hideki Koshiishi6, Shun Imajo1, Yoshimasa Tanaka8, Manabu Shinohara9, 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, The University of Tokyo, 4.Graduate School of Science, Osaka University, 5.Institute for Space-Earth Environmental Research, Nagoya University, 6.Tsukuba Space Center, Japan Aerospace Exploration Agency, 7.International Center for Space Weather Science and Education, Kyusyu University, 8.National Institute of Polar Research, 9.Kagoshima National College of Technology)

The Arase satellite observed clear dipolarization signatures at L~4.6–4.8 and magnetic local time (MLT)~5.5–5.7 h around 15:00 UT on 27 March 2017 when Dst~−70 nT. Strong magnetic field fluctuations were embedded in the dipolarization and their characteristic frequency was close to the local gyrofrequency of O+ ions. After the dipolarization, O+ flux was enhanced at 5–20 keV, while H+ flux showed no clear variations. These observations provide evidence for the selective acceleration of O+ ions by the magnetic fluctuations. At the same time, the Michibiki-1 satellite was located at L=6.6–7.1 and MLT=22.2–23.9 h. In four events out of six, magnetic field dipolarization was not identified at premidnight by Michibiki-1 but near dawn by Arase. This surprising MLT distribution of dipolarization in the inner magnetosphere may be attributed to an eastward skewing of partial ring current that is created during the storm main phase.