Collaborative Research: Flow Channel Control of Substorm Expansion Phase Spatial Coverage and Duration

合作研究：亚暴扩展阶段空间覆盖范围和持续时间的流道控制

• 批准号: 2100975
• 负责人: Yukitoshi Nishimura
• 金额: $ 8万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2100975&HistoricalAwards=false
• 关键词: Collaborative; Research; Flow; Channel; Control

Space weather describes the variations in the space environment between the sun and Earth. Space weather often manifests as substorms, where a beautiful auroral display is accompanied by an electrical current in space which can impact systems and technologies in orbit and on Earth, such as spacecrafts and power distribution systems. The substorm is localized in time (a few hours) and space (polar region). This project will benefit society by advancing understanding of space weather disturbances, which significantly affect space and susceptible ground systems. More specifically, current space weather forecasting has some validity over long time scales, but severely lacks ability to predict onset, duration, and spatial coverage of short term (e.g., substorm and streamer time scales) disturbances. This project is directly aimed at this issue by examining what determines spatial and temporal development of individual disturbances. The project will also set further precedents on coordinated use of ground-based capabilities to attack major facets of coupled magnetosphere-ionosphere physics. The team will promote research partnerships and coordination between the relevant research activities at UCLA, Boston University, and Penn State to publicize and develop new approaches for maximizing return from NSF observing facilities. The research will also continue to provide material and motivation for a UCLA freshman seminar (“Fiat Lux”) course at UCLA “Secrets of the Northern Lights: The Earth’s aurora” that has stimulated a talented, diverse, and enthusiastic group of students, leading to undergraduate research projects.The Space Weather effects of a substorm depend not only on its peak instantaneous strength, but also on the highly variable spatial extent and duration. Despite their significant importance, the spatial extent and duration has received little attention due to the lack of ideas on what may be the important factors. It has recently become known that flow channels of charged particles within the auroral oval (the ring of aurora above the Earth’s geomagnetic North Pole) that move from higher to lower latitude are a crucial feature of the oval and are responsible for the onset of a substorm. This research project will focus on the role of these flow channels that occur after substorm onset and evaluate whether they play a crucial role in controlling the local time extent, the poleward expansion, and the duration of the substorm. Since flow channel related flows and field-aligned currents map along magnetic field lines that connect the magnetosphere and ionosphere, the team will make evaluation using primarily the NSF funded (and some other) radars and all-sky imagers that have greatly improved measurements over North America of ionospheric flows and aurora (which represent upward field-aligned currents). This allows the team to make two-dimensional measurement versus time, which cannot be done with sparse spacecraft. The investigators will also make use of a major new development in 2-D flow determination from radar data. The goals of this project are to establish: 1. Are plasma flows relative to the azimuthal expansion of the brightening of the onset arc consistent with that brightening expansion being the result of azimuthal expansion of the low entropy plasma from the onset flow channel as predicted by the Rice Convection Model? 2. What is the role of post-onset flow channels outside the auroral bulge in controlling the longitudinal development of substorm expansion? 3. Are polar cap flow channels directed toward the poleward boundary of the active substorm auroral bulge important in controlling further poleward expansion and the duration of substorm expansion-phase auroral activity? 4. Is the longitudinal extent and duration of the expansion-phase-like disturbances that initiate from the auroral polar boundary controlled by polar cap flow channels?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.

太空天气描述了太阳和地球之间太空环境的变化，太空天气通常表现为亚暴，其中美丽的极光伴随着太空中的电流，这可能会影响轨道和地球上的系统和技术，例如航天器。亚暴在时间（几个小时）和空间（极地地区）方面具有局限性，该项目将通过增进对空间天气扰动的了解而特别造福于社会，因为空间天气扰动对空间和易受影响的地面系统产生了显着影响。天气预报有一定的有效性该项目通过研究决定个体空间和时间发展的因素来直接解决这个问题。该项目还将进一步开创协调使用地面能力来攻击磁层-电离层耦合物理的主要方面的先例，该团队将促进加州大学洛杉矶分校、波士顿大学和宾夕法尼亚州立大学相关研究活动之间的研究伙伴关系和协调。到宣传和开发新方法，以最大限度地提高 NSF 观测设施的回报。该研究还将继续为 UCLA 新生研讨会（“Fiat Lux”）课程“北极光的秘密：地球的极光”提供材料和动力。激发了一批才华横溢、多元化和热情的学生，促成了本科生研究项目。亚暴的空间天气影响不仅取决于其峰值瞬时强度，而且还取决于高度可变的空间范围和持续时间。由于缺乏关于什么可能是重要因素的想法，空间范围和持续时间很少受到关注，最近人们知道极光椭圆形（地球地磁北极上方的极光环）内的带电粒子流动通道。从高纬度向低纬度移动的极点是椭圆形的一个重要特征，也是亚暴爆发的原因。该研究项目将重点关注亚暴爆发后出现的这些流动通道的作用，并评估它们是否发挥了关键作用。控制中的作用当地时间范围、向极地扩展以及亚暴的持续时间，由于与流道相关的流动和场对准电流沿连接磁层和电离层的磁场线绘制，因此该团队将主要使用 NSF 资助的（和）进行评估。其他一些）雷达和全天成像仪极大地改进了北美地区电离层流和极光（代表向上的场对准电流）的测量，这使得团队能够随时间进行二维测量，而这是用现有技术无法做到的。研究人员还将利用雷达数据确定二维流的一项重大新进展。该项目的目标是确定： 1. 等离子体流是否与起始电弧增亮的方位角扩展相关。与莱斯对流模型预测的起始流道中低熵等离子体方位角扩张的结果一致。 2. 极光隆起外部的起始后流道的作用是什么？ 3. 极冠流道指向活动亚暴极光隆起的极地边界对于控制进一步向极地扩展和亚暴扩展阶段极光活动的持续时间是否重要？从极冠流道控制的极光极边界引发的类扩张相扰动的持续时间？该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，被认为值得支持影响审查标准。

项目成果

Statistical Study of Magnetospheric Conditions for SAPS and SAID

SAPS 和 SAID 磁层条件统计研究

• DOI: 10.1029/2022gl098469
• 发表时间: 2022-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Nishimura, Y.;Hussein, A.;Erickson, P. J.;Gallardo‐Lacourt, B.;Angelopoulos, V.
• 通讯作者: Angelopoulos, V.

Sensitivity of Upper Atmosphere to Different Characteristics of Flow Bursts in the Auroral Zone

高层大气对极光区爆发流不同特征的敏感性

• DOI: 10.1029/2021ja029253
• 发表时间: 2021-10
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: Sheng, Cheng;Deng, Yue;Gabrielse, Christine;Lyons, Larry R.;Nishimura, Yukitoshi;Heelis, Roderick A.;Chen, Yun-Ju
• 通讯作者: Chen, Yun-Ju

Two-Dimensional Structure of Flow Channels and Associated Upward Field-Aligned Currents: Model and Observations

流道的二维结构和相关的向上场对齐电流：模型和观测

• DOI: 10.3389/fspas.2021.737946
• 发表时间: 2021-08-31
• 作者: L. Lyons;Y. Nishimura;Chih‐Ping Wang;Jiang Liu;W. Bristow
• 通讯作者: W. Bristow

High‐Latitude Plasma Convection Based on SuperDARN Observations and the Locally Divergence Free Criterion

基于 SuperDARN 观测和局部无发散准则的高纬度等离子体对流

• DOI: 10.1029/2022ja030883
• 发表时间: 2022-12
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: Bristow, W. A.;Lyons, L. R.;Nishimura, Y.;Shepherd, S. G.;Donovan, E. F.
• 通讯作者: Donovan, E. F.

Space‐Ground Observations of Dynamics of Substorm Onset Beads

亚暴爆发珠动力学的空间-地面观测

• DOI: 10.1029/2021ja030004
• 发表时间: 2022-02
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: Nishimura, Y.;Artemyev, A. V.;Lyons, L. R.;Gabrielse, C.;Donovan, E. F.;Angelopoulos, V.
• 通讯作者: Angelopoulos, V.