[P-CG19] Planetary Magnetosphere, Ionosphere, and Atmosphere

[PCG19-01] Dynamics of Low-Energy Ions and Electrons in Mercury's Magnetosphere: A Comparison Between Mio's First and Second Flybys

*Yuki Harada¹, Yoshifumi Saito², Sae Aizawa^2,3, Nicolas André³, Lina Hadid⁴, Dominique Delcourt⁴, Moa Brita Persson^3,5, Markus Fraenz⁶, Shoichiro Yokota⁷, Andréi Fedorov³, Wataru Miyake⁸, Emmanuel Penou³, Alain Barthe³, Jean-André Sauvaud³, Bruno Katra⁴, Wolfgang Baumjohann⁹, Ayako Matsuoka¹, Werner Magnes¹⁰, Hans-Ulrich Auster¹¹, Daniel Schmid¹⁰, David Fischer¹⁰, Manabu Shinohara¹², Yoshimasa Tanaka¹³, Akiko Fujimoto¹⁴, Masaki Matsushima¹⁵, Yasuhito Narita¹⁰, Shoya Matsuda¹⁶, Go Murakami² (1.Kyoto University, 2.ISAS, JAXA, 3.IRAP, CNRS-UPS-CNES, 4.LPP-CNRS-Sorbonne Université-Ecole Polytechnique, 5.University of Tokyo, 6.Max-Planck-Institute for Solar System Research, 7.Osaka University, 8.Tokai University, 9.Austrian Academy of Sciences, 10.The Space Research Institute, Austrian Academy of Sciences, 11.Institute of Geophysics and Extraterrestrial Physics, Technical University of Braunschweig, 12.National Institute of Technology, Kagoshima College, 13.National Institute of Polar Research, 14.Kyushu Institute of Technology, 15.Tokyo Institute of Technology, 16.Kanazawa University)

Keywords:Mercury, Mio, Magnetosphere

The first two Mercury flybys by Mio have revealed new aspects of the highly dynamic magnetosphere of Mercury. Near the magnetopause and bow shock, rapid fluctuations of particle fluxes were detected at unprecedentedly high-time resolutions. In the nightside magnetotail, we identify periodic variations in the ion and electron fluxes. In the inner part of the magnetosphere, Mio observed complicated energy-time structures such as energy dispersions and inverted V's. A comparison of the data from the two flybys indicates that Mercury's magnetosphere was in completely different states, presumably resulting from different solar wind conditions. The high-quality plasma data with a help of magnetic field measurements obtained by Mio enable us to investigate the boundary dynamics, low-frequency wave activity, and substorm-related processes to an extent not achieved by the previous missions. We report up-to-date results from the ongoing efforts of data analysis regarding Mio's first two Mercury flybys.