Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

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

[P-EM13] Inner magnetosphere: Recent understanding and new insights

Wed. May 29, 2019 9:00 AM - 10:30 AM A04 (TOKYO BAY MAKUHARI HALL)

convener:Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Danny Summers(Memorial University of Newfoundland), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Shinji Saito(Graduate School of Science, Nagoya University), Chairperson:Shinji Saito(ISEE, Nagoya University), Yusuke Ebihara(RISH, Kyoto University)

9:15 AM - 9:30 AM

[PEM13-12] Instantaneous Frequency Analysis on Nonlinear EMIC Emissions: Arase Observation

*Masafumi Shoji1, Yoshizumi Miyoshi1, Yoshiharu Omura2, Lynn M Kistler1,3, Yasumasa Kasaba4, Shoya Matsuda5, Yoshiya Kasahara6, Ayako Matsuoka5, Reiko Nomura7, Keigo Ishisaka8, Atsushi Kumamoto4, Fuminori Tsuchiya4, Satoshi Yagitani6, Mariko Teramoto1, Kazushi Asamura5, Takeshi Takashima5, Iku Shinohara5 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Research Institute for Sustainable Humanosphere, Kyoto University, 3.Institute for the Study of Earth Oceans and Space, University of New Hampshire, 4.Tohoku University, 5.Institute of Space and Astronautical Science, 6.Kanazawa University, 7.National Astronomical Observatory of Japan, 8.Toyama Prefecture University)

Keywords:nonlinear wave particle interaction, Arase spacecraft

In the inner magnetosphere, the Arase spacecraft has observed electromagnetic ion cyclotron (EMIC) emissions with both rising and falling frequencies. The instantaneous frequency analyses on the electromagnetic fields of the EMIC rising tone emission have been performed by the Hilbert-Huang transform. The time variation of the instantaneous frequency shows a good agreement with the nonlinear theory for the frequency evolutions. Rapid instantaneous frequency modulation is also found during the rising tone emission. We estimate the peak-to-peak time of the fluctuation in the frequency and find that the fluctuation is caused around a half of the particle trapping time. From the motion of the phase-bunched particle around the resonant velocity, it is expected that the nonlinear resonant current, which induces the falling frequency is formed in half the trapping time.