GEM: Modeling Ultra-Low-Frequency (ULF) Waves in the Near-Earth Magnetosphere

GEM：模拟近地磁层中的超低频 (ULF) 波

基本信息

批准号：
1840891
负责人：
Robert Lysak
金额：
$ 44.61万
依托单位：
University of Minnesota-Twin Cities
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-06-01 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1840891&HistoricalAwards=false
关键词：
GEM Modeling Ultra Low Frequency

项目摘要

An outstanding question in space physics is how energy is transported throughout the near space environment. Radio waves at ultra-low frequencies (0.3-3 kHz) serve as both a transport mechanism for energy throughout the magnetosphere and ionosphere and an important diagnostic of the space plasma properties. This project creates a new physics-based model to better understand the dynamics of the near-Earth space environment. The broader impacts of this project include developing new models relevant to our understanding and prediction of space weather - a national priority set out in the National Space Weather Action Plan - and the training of a graduate student.Ultra-low-frequency (ULF) waves play a major role in the transport of energy in the near-Earth regions of the magnetosphere. The research will involve the development of a magnetohydrodynamic (MHD) wave code and its application to several problems involving ULF waves in the magnetosphere. The primary focus will be on the application of this model to problems in magnetoseismology, using these waves as a diagnostic of the plasma distribution throughout the magnetosphere. This can be accomplished both by a study of the properties of field line resonances as well as through the travel times of ULF waves from an impulsive source. While previous versions of the wave code have either been two-dimensional, or three-dimensional but with azimuthal symmetry, the code now allows for local time dependence of the ionosphere and plasmasphere. This allows for studies of the day-night differences in the ionosphere as well as the role of conductivity enhancements, such as in the auroral zone, or depletions, as can occur in the sub-auroral plasma trough. Including plasmaspheric asymmetry will allow for the dawn-dusk differences in the plasmasphere structure, including the possible presence of plasmaspheric plumes. Development and application of a global ULF wave model that can investigate these interactions is the primary goal of the research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

太空物理学的一个杰出问题是如何在整个近太空环境中运输能源。在超低频率（0.3-3 kHz）处的无线电波既可以作为整个磁层和电离层的能量的传输机制，也是空间等离子体特性的重要诊断。该项目创建了一个新的基于物理的模型，以更好地了解近地太空环境的动态。该项目的更广泛影响包括开发与我们对太空天气的理解和预测有关的新模型 - 国家太空天气行动计划中提出的国家优先级 - 培训研究生。欧拉 - 低频（ULF）波在磁层近美地区的能源运输中起着重要作用。该研究将涉及磁性水力学（MHD）波代码的开发及其在磁层中涉及ULF波的几个问题上的应用。主要的重点将是将该模型应用于磁质学中的问题，将这些波用作整个磁层的血浆分布的诊断。这既可以通过对野战线共振的性质以及冲动来源的ULF波的旅行时间进行研究来实现。尽管波浪代码的先前版本要么是二维或三维，但具有方位角对称性，但该代码现在允许电离层和等离子体的局部时间依赖性。这允许研究电离层的昼夜差异以及电导率增强的作用，例如在极光区或耗尽的耗尽，就像在隆起的血浆槽中可能发生的那样。包括等离子不对称性在内，将允许等离子体结构中的黎明dusk差异，包括可能存在等离子体羽流。可以调查这些相互作用的全球ULF波浪模型的开发和应用是研究的主要目标。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来评估值得支持的。