The Differences in Onset Times of Hemispherically Conjugate Auroral Stations

半球共轭极光站出现时间的差异

• 批准号: 1606014
• 负责人: James Weygand
• 金额: $ 14.55万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1606014&HistoricalAwards=false
• 关键词: Differences; Onset; Times; Hemispherically; Conjugate

This is a one-year pilot study of a project classified as "high risk - high reward". The project will study hemispheric differences in the onset times of individual substorms and other auroral events observed simultaneously in the northern and southern auroral regions. Magnetic substorms (as they are called) reshape the Earth's magnetotail far out in Geospace. This process explosively releases energy powering an immediate intensification of currents and energetic charge particle precipitation closer to Earth in the ionosphere at the foot points of the affected field lines, and an intensification of auroral emissions. The investigation will take advantage of recently completed pairings of magnetometer stations located at the two Earthward ends of magnetic field lines that thread through the Earth's magnetotail where substorms are initiated. Differences in timing as well as the sequence of auroral features that precede the onset in each hemisphere will provide new information about, and place additional constraints on, controversial and still intensely debated theories about the underlying physical process(es) responsible for these extremely dynamic events. Significant closure risk is introduced in this project (which has never before been attempted) by the need to separate out the difference in timing due to the substorm process itself in the magnetosphere from other sources of timing offsets, for example, due to slight inter-hemispheric differences in the propagation path of a substorm onset signature into the magnetometer field of view. Whether these additional sources of timing differences can be removed using auroral images or other information, and the true substorm-related timing differences extracted, is the primary focus of this pilot study. The high reward of this technique, if proven feasible, is a new view into a long standing Geospace puzzle that continues to hinder progress in understanding severe space weather in the Earth's vicinity. Progress is important because in the hazardous radiation environment in near-Earth space, astronauts carry human enterprises into space and satellites that are key to important societal infrastructures orbit. The intense abrupt changes in the magnetic field associated with these explosive events induce currents in the solid Earth threatening long-term damage and shorter-term (potentially dangerous) disruptions in the operation of electric power grids. This pilot study will provide an educational experience to an undergraduate and a graduate student, contributing to the development of the future scientific workforce. The project is a statistical study that aims to identify significant difference between the hemispheres in the onset time for individual substorms as measured by signatures of the onset in ground-based magnetometers. Given this information, it may be possible to determine which of two prominent substorm models are more consistent with the timing observations. The second phase of the project will look to identify causes of the differences by examining the orientation of the interplanetary magnetic field, solar wind conditions, and the Universal Time during the substorm onset. A smaller study will compare onset differences with those observed in a pair of conjugate all-sky imagers, when available.

这是一项为期一年的试点研究，被列为“高风险-高回报”项目。 该项目将研究在北方和南方极光区同时观测到的个别亚暴和其他极光事件的开始时间的半球差异。 磁亚暴（正如它们被称为的那样）重塑了地球空间中遥远的地球磁尾。 这一过程爆炸性地释放出能量，使电流和高能电荷粒子在受影响的场线脚点的电离层中更接近地球的地方迅速加强，并使极光发射加强。 这次调查将利用最近完成的磁力计站配对，这些磁力计站位于穿过地球磁尾的磁场线的两个朝向地球的末端，亚暴就是在那里开始的。 在时间上的差异，以及极光特征的顺序，在每个半球的发病之前，将提供新的信息，并放置额外的限制，有争议的和仍然激烈争论的理论，有关的基本物理过程（一个或多个）负责这些极其动态的事件。 由于需要将磁层中亚暴过程本身造成的时间差异与其他时间偏移源（例如，进入磁强计视野的亚暴开始特征的传播路径存在轻微的半球间差异）分开，因此在该项目中引入了重大的关闭风险（以前从未尝试过）。 这些额外的时间差异的来源是否可以使用极光图像或其他信息，并提取真正的亚暴相关的时间差异，是这个试点研究的主要重点。 这项技术的高回报，如果被证明是可行的，是一个长期存在的地球空间难题，继续阻碍在了解地球附近的严重空间天气的进展一个新的观点。 取得进展很重要，因为在近地空间危险的辐射环境中，宇航员将人类企业带入太空，而卫星是重要社会基础设施的关键。 与这些爆炸事件相关的磁场剧烈突变在固体地球中感应出电流，可能对电网的运行造成长期损害和短期（潜在危险）中断。 这项试点研究将为本科生和研究生提供教育经验，为未来科学劳动力的发展做出贡献。该项目是一项统计研究，目的是通过地面磁力计的起始特征来确定半球之间在个别亚暴起始时间上的重大差异。 有了这些信息，就有可能确定两个著名的亚暴模型中哪一个与观测时间更一致。 该项目的第二阶段将通过检查行星际磁场的方向，太阳风条件和亚暴爆发期间的世界时来确定差异的原因。 一个较小的研究将比较在一对共轭全天空成像仪中观察到的起始差异。