日本地球惑星科学連合2018年大会

講演情報

[EE] Eveningポスター発表

セッション記号 P (宇宙惑星科学) » P-PS 惑星科学

[P-PS01] Outer Solar System Exploration Today, and Tomorrow

2018年5月21日(月) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:木村 淳(大阪大学)、笠羽 康正(東北大学大学院 理学研究科 地球物理学専攻)、Vance Steven(Jet Propulsion Laboratory, Caltech、共同)、Kunio M. Sayanagi (Hampton University)

[PPS01-P09] A simulation study on solar wind influence on long-term variation of Jovian Synchrotron Radiation

*韓 秀萬1村上 豪2北 元3土屋 史紀3垰 千尋4サントスコスタ ダニエル5山崎 敦2中村 正人2 (1.東京大学 理学系研究科 地球惑星科学、2.宇宙航空研究開発機構 宇宙科学研究所、3.惑星プラズマ大気研究センター、4.情報通信研究機構、5.Southwest Research Institute)

キーワード:Hisaki、Jupiter、Synchrotron、Radiation、Solar

Jovian Synchrotron Radiation (JSR) is a non-thermal radiation emitted by relativistic electrons trapped by Jovian magnetic field, whose frequency range is usually between a few hundred MHz and a few GHz. Based on the assumption that the source of electron is at some outer boundary (e.g. 6 Jovian Radii) and radial diffusion of electrons occur due to the violation of third adiabatic invariant, a number of diffusion models in the past could explain the steady profile of electron population and the resulted total flux density of JSR. Yet, the reason behind its time variation remains unclear, especially, no model could reproduce the long-term variation whose JSR amplitude is 20 ~ 30%, which has a strong correlation with solar wind dynamic pressure shifted 2 ~ 3 years forward in time.
In our study, we have made a radial diffusion model taking Hisaki's observation result into account that dawn-to-dusk electric field is present and is modulated with solar wind dynamic pressure. New diffusion coefficient is applied here in terms of solar wind dynamic pressure, and relative JSR amplitude is calculated according to the pressure variation between 1971 and 2005. By comparing with an observation at 2.3 GHz, we present our result that JSR amplitude of 20 ~ 30 % and a strong correlation between JSR and time-shifted solar wind dynamic pressure can be sucessfully recovered between 1971 and 1989, and discuss why and how long-term variation happens. For the period later than 1989 where the correlation is mostly lost, one might have to look for another possibility (e.g. active volcanic Io's activity).