A Theoretical Study of Time-Dependent Magnetosphere Ionosphere Coupling

时变磁层电离层耦合的理论研究

• 批准号: 9301043
• 负责人: Robert Lysak
• 金额: $ 24.57万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1998-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9301043&HistoricalAwards=false
• 关键词: Theoretical; Study; Time; Dependent; Magnetosphere

9301043 Lysak The primary goals of the first GEM campaign are an understanding of the mapping of dayside magnetopause processes to the ionosphere and a determination of the ionospheric signatures of such processes. Although previous attempts have been made to consider the static mapping of magnetopause processes to the ionosphere, the fact that the Alfven transit time from the magnetopause to the ionosphere is comparable to the evolution time of magnetopause processes suggests that the dynamics of this coupling is important. This proposed work focuses on an investigation of these effects by means of a three-dimensional model of coupling of the magnetosphere and ionosphere by means of Alfven waves which considers the global, linear response of the magnetosphere and ionosphere to perturbations at the magnetopause. In this model, perturbations representing magnetopause processes such as transient reconnection, Kelvin-Helmholtz instabilities or dynamic pressure pulses can be imposed on the magnetopause, and the resulting ionospheric signature can be self-consistently calculated. This model will be extended to include finite pressure effects, finite ionospheric conductivity and a generalized magnetic field geometry. This project will be supported by two related projects, one of which considers a localized model of a diverging auroral flux tube which includes nonlinearities, ionospheric dynamics and parallel electric fields. The other related project is an investigation of transport processes at the magnetopause and their role in the generation of field-aligned currents. The numerical results will be compared with data from ground magnetometer arrays in order to determine the most likely source for the observed magnetic vortices. ***

9301043 Lysak第一次全球磁层运动的主要目标是了解日侧磁层顶过程与电离层的对应关系，并确定这种过程的电离层特征。尽管以前曾试图考虑磁层顶过程到电离层的静态映射，但从磁层顶到电离层的Alfven渡越时间与磁层顶过程的演变时间相当这一事实表明，这种耦合的动力学是重要的。这项拟议的工作侧重于通过Alfven波的磁层和电离层耦合的三维模型来研究这些影响，该模型考虑了磁层和电离层对磁层顶扰动的全球线性响应。在这个模型中，可以对磁层顶施加表示磁层顶过程的扰动，如瞬时重联、Kelvin-Helmholtz不稳定性或动态压力脉冲，由此产生的电离层特征可以自洽地计算。该模型将被扩展到包括有限压力效应、有限电离层电导率和广义磁场几何。该项目将得到两个相关项目的支持，其中一个项目考虑了一个包含非线性、电离层动力学和平行电场的极光发散通量管的局部化模型。另一个相关项目是调查磁层顶的输运过程及其在产生场向电流中的作用。数值结果将与地面磁力计阵列的数据进行比较，以确定观测到的磁旋涡的最可能来源。***