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. ***

小行星9301043 第一次全球监测系统活动的主要目标是了解昼侧磁层顶过程到电离层的映射情况，并确定这种过程的电离层特征。 虽然以前的尝试已经作出考虑磁层顶过程的电离层的静态映射，阿尔芬过境时间从磁层顶到电离层的事实是可比的磁层顶过程的演变时间表明，这种耦合的动态是重要的。 这项拟议工作的重点是调查这些影响的三维模型的磁层和电离层耦合的阿尔芬波的手段，认为全球性的，线性响应的磁层和电离层的扰动在磁层顶。 在这个模型中，代表磁层顶过程的扰动，如瞬时重连、开尔文-亥姆霍兹不稳定性或动态压力脉冲，可以施加在磁层顶上，由此产生的电离层特征可以自洽地计算。 这个模型将被扩展到包括有限的压力效应，有限的电离层电导率和一个广义的磁场几何。 这一项目将得到两个相关项目的支持，其中一个项目考虑一个发散极光通量管的局部模型，其中包括非线性、电离层动态和平行电场。 另一个相关项目是调查磁层顶的运输过程及其在产生场向电流方面的作用。 数值结果将与地面磁力计阵列的数据进行比较，以确定观测到的磁涡最可能的来源。 ***