Numerical study on plasma dynamics in the Earth magnetosphere in association with characteristic distributions of aurora and field-aligned currents

地球磁层等离子体动力学与极光和场对准电流特征分布的数值研究

• 批准号: 07804029
• 负责人: YAMAMOTO Takashi
• 金额: $ 1.34万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07804029/
• 关键词: Field-aligned Current; Auroral Omega Band; Auroral Oval; Interplanetary Magnetic Field; Charge Separation; Plasma Torus; Numerical Simulation; Interchange Instability; 磁気圏・電離圏結合; 2次元数値シミュレーション; プラズマ粒子加速; 異常拡散; 磁力線開-閉境界; 領域"0"対電流; トーラス配位; オメ

So far, the theoretical models for the earth magnetosphere have normally assumed that the distribution of auroral particles with kinetic energies of 1-10 keV is uniform, in terms of the flux tube content, over the auroralzone. This implies that no charge separation occurs in that region, despite of the remarkable activity of aurora, and that boundary processes such as viscous interaction and magnetic reconnection play important roles in the auroral activity and production of region 1 field-aligned currents (FACs). We propose a new paradogm that during a period of southward interplanetary magnetic field (IMF), the so-called plasma 'torus' with plasma concentration on the auroral oval can be formed due to particle escape along the open field lines, and that distortion of the torus configuration by the two-cell convection results in the generaation of the region 1 and region 2 FACs. The plasma torus had been assumed to be absolutely interchange-unstable, and thus it had not been considered as a realistic distribution of the magnetospheric plasma. However, if reversal of the magnetic drift direction across the open-close boundary is taken into account, one can expect that the whole configuration of the torus can be maintained while the interchange instability occurs locally inside it. Our theory predicts that various phenomena such as production of region 0,1 and 2 FACs and formations of discrete aurora and omega band structure are interpreted as results of active behavior of the plasma torus which is "metabolized" through the processes of plasma flow into the tours from the solar wind the plasma escape. The purpose of our numerical simulation is to reproduce the metabolized torus as well as those auroral phenomena. Recently we have obtained the simulation results of the region 0,1 and 2 FACs and the formation of auroral omega band, which are consistent with the satellite servations.

迄今为止，地球磁层的理论模型通常假定动能为1-10 keV的极光粒子在极光带上的分布是均匀的，就通量管含量而言。这意味着，在该地区没有发生电荷分离，尽管极光的显着活动，边界过程，如粘性相互作用和磁场重联发挥重要作用的极光活动和生产区域1场向电流（FACs）。我们提出了一个新的Paradogm，即在行星际磁场（IMF）向南的时期，由于粒子沿着开放场线逸出，可以形成所谓的等离子体“环面”，等离子体浓度位于极光椭圆形上，并且由于双胞对流导致环面配置的扭曲导致区域1和区域2 FAC的产生。等离子体环被认为是绝对不稳定的，因此它没有被认为是磁层等离子体的实际分布。然而，如果考虑到磁漂移方向在开-闭边界上的反转，可以预期，当交换不稳定性局部发生在环内部时，环的整个构型可以保持。我们的理论预测了各种现象，如区域0的产生，1和2FACs和离散极光和欧米茄带结构的形成被解释为等离子体环的活动行为的结果，通过等离子体流入图尔斯的过程，等离子体从太阳风中逃逸。我们数值模拟的目的是再现代谢环以及极光现象。最近我们得到了0、1、2区FAC和极光欧米加带形成的模拟结果，这些结果与卫星观测的结果是一致的。

项目成果

T.Yamamoto: "A theory for generation of the paired region 1 and region 2 field-aligned currents" J.Geophys. Res.102, A2. 27199-27222 (1996)

T.Yamamoto：“生成配对区域 1 和区域 2 场对准电流的理论”J.Geophys。

T.Yamamoto: "Quasi-steady production of region 1 and region 2 field-aligned currents" Prod.NIPR Symp.Upper Atmos.Phys.11. 108-123 (1998)

T.Yamamoto：“区域 1 和区域 2 场对准电流的准稳定产生”Prod.NIPR Symp.Upper Atmos.Phys.11。

T.Yamamoto: "Formation of auroral omega bands in the paired region 1 and region 2 field-aligned current system" J.Geophys. Res.101, A12. 2571-2544 (1997)

T.Yamamoto：“在配对的区域 1 和区域 2 场对准电流系统中极光欧米茄带的形成”J.Geophys。

T.Yamamoto: "A theory for generation of the paired region 1 and region 2 field-aligned currents" J.Geophys.Res.101 A12. 27199-27222 (1996)

T.Yamamoto：“生成配对区域 1 和区域 2 场对准电流的理论”J.Geophys.Res.101 A12。

T.Yamamoto: "Numerical study on dynamics and polarization of the hot plasma torus in the magneto-sphere:cause of generation of the paired region 1 and region 2 field-aligned currents" J.Geomag.Geoelectr.49,7. 879-922 (1997)

T.Yamamoto：“磁层中热等离子体环面动力学和极化的数值研究：成对区域 1 和区域 2 场对准电流的生成原因”J.Geomag.Geolectr.49,7。