GEM: Resolving the Unique Characteristics of Substorms that Precede Strong Thermal Emission Velocity Enhancement (STEVE) Events

GEM：解决强热发射速度增强 (STEVE) 事件之前的亚暴的独特特征

• 批准号: 2225972
• 负责人: Lindsay Goodwin
• 金额: $ 39.21万
• 依托单位: New Jersey Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2225972&HistoricalAwards=false
• 关键词: GEM; Resolving; Unique; Characteristics; Substorms

A Strong Thermal Emission Velocity Enhancement (STEVE) is a latitudinally narrow and longitudinally elongated optical emission that appears in the night sky before midnight, equatorward of the auroral oval. Importantly, STEVE is not an aurora in the classic sense - as far as we can tell STEVE's emissions are not generated by charged particles streaming down magnetic field lines and colliding with the neutral atmosphere to produce optical emissions. In fact, the exact mechanism for STEVE's optical emissions have yet to be identified. However, STEVEs are correlated with events called substorms which involve energy releases in the Earth's nightside magnetic field, which often manifest as dynamic auroral displays. This research focuses on the observation that most substorms do not result in a STEVE event (approximately only 3% do), indicating that substorms that occur with STEVE events are unique. To better understand STEVE associated substorms and the conditions under which STEVEs occur, we will use data from all-sky imagers, spacecraft, radars, magnetometers, and citizen scientists – who were the ones who initially discovered STEVE. Using these datasets, the evolution from substorm to STEVE (or no STEVE) will be monitored. Additionally, we will investigate and specify the geomagnetic conditions unique to STEVE events. This work will strengthen our understanding of the upper atmosphere and the near-Earth geospace environment, allowing us to better mitigate space weather effects. Furthermore, given the team and collaborations this project will support, this research will promote education and diversity, and strengthen collaborations within the solar-terrestrial science community.Strong Thermal Emission Velocity Enhancement (STEVE) events are bright mauve optical emissions that periodically occur between dusk and midnight in subauroral regions after a substorm onset. It has been established that STEVE is correlated with substorms, and more specifically the recovery phase of a substorm. Importantly, not all substorms are associated with a STEVE event, but all STEVE events are associated with a substorm. The motivation of this work is to determine how the substorms associated with STEVE events are unique compared to other substorms. This will be done by addressing three science questions: 1) What is the temporal response of the magnetosphere-ionosphere system to substorm onset in associated STEVE events? 2) What are the conditions of the magnetosphere-ionosphere system prior to a STEVE event; can preconditioning be identified? and 3) How are the auroral and sub-auroral mesoscale flow patterns associated with STEVE events different from those associated with substorm events in general? We will use all-sky imagers, spacecraft, radars, magnetometers, and citizen science data to address the aforementioned questions. A novel and compelling component of this research effort will be the incorporation of radar data, in particular Incoherent Scatter Radar (ISR) data. This will allow us to complement existing measurements provided by imagers and spacecraft and also enhance our ability to identify undiscovered STEVE events. The ionospheric signature of a STEVE event in ISR data has recently been identified and will be used to find and characterize additional STEVE events in the work.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.

强热发射速度增强（STEVE）是一种纬度狭窄、纵向拉长的光学发射，出现在午夜之前的夜空中，极光椭圆形的赤道方向。重要的是，STEVE 并不是经典意义上的极光——据我们所知，STEVE 的发射不是由带电粒子沿着磁场线流动并与中性大气碰撞产生光发射而产生的。事实上，史蒂夫光发射的确切机制尚未确定。然而，STEVE 与亚暴事件相关，亚暴事件涉及地球夜间磁场中的能量释放，通常表现为动态极光显示。这项研究的重点是观察到大多数亚暴不会导致 STEVE 事件（大约只有 3% 会导致），这表明与 STEVE 事件一起发生的亚暴是独一无二的。为了更好地了解与 STEVE 相关的亚暴以及 STEVE 发生的条件，我们将使用来自全天成像仪、航天器、雷达、磁力计和公民科学家（他们是最初发现 STEVE 的人）的数据。使用这些数据集，将监测从亚暴到 STEVE（或无 STEVE）的演变。此外，我们将调查并指定 STEVE 事件特有的地磁条件。这项工作将加强我们对高层大气和近地地球空间环境的了解，使我们能够更好地减轻空间天气影响。此外，考虑到该项目将支持的团队和合作，这项研究将促进教育和多样性，并加强日地科学界内的合作。强热发射速度增强（STEVE）事件是明亮的紫红色光学发射，在亚暴爆发后的黄昏和午夜之间周期性地发生在亚极光地区。已经确定 STEVE 与亚暴相关，更具体地说，与亚暴的恢复阶段相关。重要的是，并非所有亚暴都与 STEVE 事件相关，但所有 STEVE 事件都与亚暴相关。这项工作的动机是确定与 STEVE 事件相关的亚暴与其他亚暴相比有何独特之处。这将通过解决三个科学问题来完成：1）磁层-电离层系统对相关 STEVE 事件中的亚暴爆发的时间响应是什么？ 2）STEVE事件发生前磁层-电离层系统的状况如何；可以识别预处理吗？ 3）与 STEVE 事件相关的极光和亚极光中尺度流动模式与一般的亚暴事件相关的流动模式有何不同？我们将使用全天空成像仪、航天器、雷达、磁力计和公民科学数据来解决上述问题。这项研究工作的一个新颖且引人注目的组成部分将是雷达数据的结合，特别是非相干散射雷达（ISR）数据。这将使我们能够补充成像仪和航天器提供的现有测量结果，并增强我们识别未被发现的 STEVE 事件的能力。 ISR 数据中 STEVE 事件的电离层特征最近已被识别，并将用于查找和表征工作中的其他 STEVE 事件。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。