Large Scale Magnetotail Dynamics and Auroral Precipitation

大规模磁尾动力学和极光降水

• 批准号: 9414760
• 负责人: Maha Ashour-Abdalla
• 金额: $ 21.56万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-01-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9414760&HistoricalAwards=false
• 关键词: Large; Scale; Magnetotail; Dynamics; Auroral

This proposal outlines a study of the formation of auroral arcs caused by the large scale dynamics of ions and electrons in the magnetotail. The first step is to construct ion distribution functions moments (density, temperature, pressure, etc.) in a three-dimensional large scale magnetospheric model. This will be done using the technique of large scale kinetics, whereby thousands of ion trajectories are launched from a variety of sources into a magnetic and electric field model of the magnetosphere. The 3D auroral precipitation profile (with local time dependence) will be determined and compared with observations. The second step will be to perform a similar large scale kinetic study using electrons, after which the ion and electron results will be compared and in regions where there are charge imbalances, parallel electric fields will be imposed. The precipitated electron flux will then be calculated and theoretical auroral images will be produced. The third step is to introduce time dependence into the large scale kinetic model. This will be done by using different field model "snapshots" which represent different states (i.e., growth phase, recovery, etc.) of the magnetosphere and calculating the ion and electron precipitation profiles. Once a general understanding using these snapshots has been achieved, an attempt will be made to model the growth phase by temporally evolving the quiet time field model to a more disturbed time. The last step is to bring all of these results together to delineate the formation of auroral arcs. The physical mechanisms in the magnetotail that result in the large longitudinal extent of auroral arcs will be identified and the results will be compared to observations.

本文概述了磁尾中离子和电子的大规模动力学引起的极光弧形成的研究。第一步是在三维大尺度磁层模型中构造离子分布函数矩（密度、温度、压力等）。这将使用大规模动力学技术来完成，其中数千个离子轨迹从各种来源发射到磁层的磁场和电场模型中。将确定三维极光降水剖面（与当地时间有关），并与观测结果进行比较。第二步将使用电子进行类似的大规模动力学研究，之后将比较离子和电子的结果，并在存在电荷不平衡的区域施加平行电场。然后将计算析出的电子通量，并产生理论上的极光图像。第三步是在大尺度动力学模型中引入时间依赖性。这将通过使用不同的场模型“快照”来完成，这些“快照”代表磁层的不同状态（即，生长阶段，恢复等），并计算离子和电子沉淀剖面。一旦使用这些快照获得了一般的理解，将尝试通过将安静时间场模型在时间上演化为更受干扰的时间来模拟生长阶段。最后一步是把所有这些结果结合起来描绘极光弧的形成。将确定磁尾中导致极光弧纵向范围大的物理机制，并将结果与观测结果进行比较。