日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM11] Dynamics of Magnetosphere and Ionosphere

2019年5月29日(水) 13:45 〜 15:15 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:中溝 葵(情報通信研究機構 電磁波研究所)、尾崎 光紀(金沢大学理工研究域電子情報学系)、藤本 晶子(九州工業大学)、堀 智昭(名古屋大学宇宙地球環境研究所)

[PEM11-P04] 磁気圏電離圏対流と磁場構造の相互作用

*藤田 茂1田中 高史2渡辺 正和2 (1.気象庁気象大学校/国立極地研究所、2.九州大学)

キーワード:convection、null-separartor structure

The steady convection in the magnetosphere-ionosphere coupling system is composed of the following self-consistent elementary processes; dynamo in the cusp-mantle region, the field-perpendicular current system in the magnetosphere, the field-aligned current system connecting the ionosphere, the ionospheric electric field, the magnetospheric convection corresponding to the ionospheric electric field, and the high plasma pressure distribution in the cusp region [Tanaka, 2007].

The energy of the convection is transported from the solar wind across the magnetopause where the magnetic field configures the null-separator structure. Since the magnetic field configuration of the null-separator structure is originally derived from the superposition of two scalar fields [Stern, 1973], say, the dipole field and the uniform field, the magnetic field of the null-separator would not have free energy necessary for plasma acceleration. However, the simulation reveals that the magnetic field has a tension force near the null point. Therefore, we need a mechanism that transports the energy to this region.

It is revealed from the simulation that the bow shock supplies the energy. Indeed, the current from the bow shock deforms the magnetic field of the null-separator structure. In addition, it is noted that the Chapman-Ferraro current also deforms the magnetic field configuration in the magnetopause. This fact indicates that the convection system in the magnetosphere contributes to deformation of the null-separator structure. That is to say, energy transport from the solar wind to the magnetosphere-ionosphere compound system is affected by the physical processes in the convection. Therefore, as a result of the interaction between the magnetosphere-ionosphere convection and the null-separator structure, the magnetosphere-ionosphere compound system can be extended to the solar wind-magnetosphere-ionosphere compound system.



References

T. Tanaka (2007), Magnetosphere-Ionosphere Convection as a Compound System, Space Sci Rev, 133, 1-72, DOI 10.1007/s11214-007-9168-4.

Stern, D. P. (1973), A study of the electric field in an open magnetospheric model, J. Geophys. Res., 78(31), 7292-7305, doi:10.1029/JA078i031p07292.