Numerical study on physics on physics of auroral pattern formation and plasma elementary processes

极光图案形成和等离子体基本过程物理数值研究

• 批准号: 04804028
• 负责人: YAMAMOTO Takashi
• 金额: $ 1.22万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04804028/
• 关键词: Magnetosphere-Ionosphere Coupling; Field-Aligned Current; Interaction between Solar Wind and Magnetosphere; Low-Latitude Boundary Layr; Auroral Omega Band; Plasma Sheet; Two Dimensional Particle Simulation; Charge Separation; 2次元粒子シミュレーション; 中性大気ダ

(1) Our theoretical study on the characteristic pattern of auroras projected on the ionosphere has elucidated fundamental plasma physics for natural phenomena in the magnetosphere/ionosphere system. First, the processes of charge separation in the magnetosphere have been identified as being responsible for the auroral traveling surge, the omega bands, and the ripples. (The causes of these auroral phenomena had long been beyond understanding of theoretical researchers.) Our approach is unique : by using particle simulations we reproduce the temporal/spatial development of auroras on the ionosphere which is in good agreement with the observations. We further apply the simulation-based analysis to the problem of quasi-steady field-aligned currents. Similarly to the case of auroral dynamics, we successfully reproduced the observatioanlly identified pattern of region 1 and region 2 field-aligned current by the two dimensional simulations. This result leads naturally to a new concept that the paired region 1/region2 field-aligned currents can be produced from the plasma distortion in the closed magnetosphere by the solar wind externally applied in the polar cap region.(2) Using the d magnetic field model by Tsyganenko, we numerically obtained the distributions of magnetic drift vectors in the magnetically closed region where the effect of the interplanetary magnetic field is relatively small. From this plot we found that the field-aligned currents in the low-latitude boundary layr (LLBL) is likely to be caused by the pressure gradient of a plasma injected from the magnetosheath. (Paper will be presented at SGEPSS,in March 1995.) We will also argue that some features of the LLBL current system, which have been revealed by recent satellite observations, could not be understood in a model of the viscous interaction between the magnetosphere and the solar wind which had long been believed to be a most likely mechanism for the LLBL current generation.

（1）我们关于在电离层上投影的光环的特征模式的理论研究已经阐明了磁层/电离层系统中自然现象的基本等离子体物理。首先，磁层中的电荷分离过程已被确定为负责极光流行潮，欧米茄带和涟漪。 （这些极光现象的原因长期以来一直无法理解理论研究人员。）我们的方法是独一无二的：通过使用粒子模拟，我们在电离层上重现了Auroras的时间/空间发育，这与观察值非常吻合。我们进一步将基于仿真的分析应用于准稳态场对准电流的问题。与极光动力学的情况类似，我们成功地复制了通过两个维度模拟的区域1和区域2野外对准电流的模式。该结果自然导致了一个新概念，即配对区域1/区域2场对齐的电流可以通过在极盖区域外部应用的太阳能施加在封闭磁层中的血浆中的血浆扭曲。从这个图中，我们发现低纬度边界Layr（LLBL）中的场对准电流可能是由从磁石注入的等离子体的压力梯度引起的。 （论文将于1995年3月在SGEPSS发表。）我们还将争辩说，LLBL当前系统的某些特征是在最近的卫星观察结果中揭示的，在磁层和太阳能之间的粘性相互作用的模型中无法理解，这是长期以来一直认为是LLBL Blbl Estrens Generation的最可能的机制。

项目成果

Takashi YAMAMOTO: "Convective Generation of 〃Giant〃Undulations on the Evening Diffuse Auroral Boundary" Journal of Geophysical Research. 99. 19499-19512 (1994)

Takashi YAMAMOTO：“晚间漫射极光边界上的对流生成”，《地球物理研究杂志》99。19499-19512（1994）。

T. Yamamoto: "A Particle Simulation of the Westward-Traveling Surge" J. Geophys. Res.98. 13653-13675 (1993)

T. Yamamoto：“西行热潮的粒子模拟”J. Geophys。

T. Yamamoto: "A Particle Simulation of Auroral Omega Bands and Torchlike Structures" J. Geomag. Geoelectr.45. 619-648 (1993)

T. Yamamoto：“极光欧米伽带和火炬状结构的粒子模拟”J. Geomag。

Takashi YAMAMOTO: "A Particle Simulation of the Westward-Traveling Surge" Journal of Geophysical Research. 98. 13653-13675 (1993)

Takashi YAMAMOTO：“西行涌流的粒子模拟”地球物理研究杂志。

Takashi YAMAMOTO: "A Theory of Current Generator in the Magnetosphere-Ionosphere Coupling" Proc.NIPR Symp.Upper Atmos.Phys.6. (1993)

Takashi YAMAMOTO：“磁层-电离层耦合中的电流发生器理论”Proc.NIPR Symp.Upper Atmos.Phys.6。