Structure and Evolution of Dayside Diffuse Aurora and Enhanced Magnetospheric Density Regions from Coordinated Observations of South Pole All-Sky Imager and THEMIS Spacecraft

南极全天成像仪和 THEMIS 航天器协调观测的日侧漫射极光和增强磁层密度区域的结构和演化

• 批准号: 1341359
• 负责人: Yukitoshi Nishimura
• 金额: $ 50.33万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1341359&HistoricalAwards=false
• 关键词: Structure; Evolution; Dayside; Diffuse; Aurora

Plasma density is one of the fundamental quantities of the magnetosphere-ionosphere (M-I) coupling that affects the growth and propagation of various plasma wave modes, magnetic reconnection rate, and ionospheric conductance; all of which strongly influence energy and mass transport in the M-I system. By taking advantage of simultaneous satellite-ground conjunctions in recent years, this award will help determining the source region of dayside density modulations, specifically addressing three outstanding scientific questions: Where does the enhanced density originate? How do enhanced density regions evolve in time? And what is the typical size of the enhanced density regions?The plasma density in the dayside magnetosphere is highly structured, and this structure can have a large impact on the excitation of whistler-mode waves that in turn scatter plasma sheet electrons drifting from the nightside and accelerate electrons in the Earth's radiation belts. It has been recently found that whistler-mode waves drive structured patches of the diffuse aurora; this can be used to highlight enhanced density regions in the dayside magnetosphere. The dayside 'aurora-wave-density' correlations lead to questions about the origin of enhanced plasma density patches and their propagation in the dayside magnetosphere. Satellite observations alone have difficulties separating spatial and temporal effects in tracing the motion of enhanced density regions, but ground-based 2D auroral imaging could offer an excellent technique for monitoring the shape and motion of diffuse aurora that is driven by precipitating energetic electrons interacting with whistler-mode waves. The proposed investigation will use a creative approach for understanding dayside magnetospheric density evolution by using Antarctic-based auroral observations. In particular, South Pole is an ideal dayside auroral observatory due to its longest polar night in the world. The wave-particle interaction producing whistler-mode waves will be used as a tool for imaging dayside plasma density structures using correlated South Pole all-sky auroral imager and THEMIS spacecraft observations. This research may influence not only its own field of diffuse auroral studies, but also related fields such as dayside magnetospheric dynamics, wave particle interactions, and excitation of plasma waves. This interesting and important scientific research provides an ideal opportunity to train a graduate student, further scientific collaboration and cooperation in Antarctica, and create a list of THEMIS-South Pole auroral imager 'dayside conjunction' events and respective geomagnetic field mapping results for the use by a broader geospace science community.

等离子体密度是磁层-电离层（M-I）耦合的基本量之一，影响各种等离子体波模式的生长和传播、磁重联率和电离层电导；所有这些都强烈影响 M-I 系统中的能量和质量传输。通过利用近年来同步卫星与地面的结合，该奖项将有助于确定日侧密度调制的源区域，特别是解决三个突出的科学问题：增强的密度源自何处？密度增强区域如何随时间演化？增强密度区域的典型大小是多少？白天磁层中的等离子体密度是高度结构化的，这种结构可以对哨声模式波的激发产生很大影响，而哨声模式波又会散射从夜间漂移的等离子体片电子并加速地球辐射带中的电子。最近发现，哨声模式波驱动漫射极光的结构化斑块。这可用于突出显示日侧磁层中的密度增强区域。日侧“极光波密度”相关性引发了有关增强等离子体密度斑块的起源及其在日侧磁层中传播的问题。仅靠卫星观测很难区分追踪密度增强区域运动的空间和时间效应，但地面二维极光成像可以提供一种出色的技术来监测漫射极光的形状和运动，而漫射极光是由与哨声相互作用的高能电子沉淀驱动的。 -模波。拟议的调查将采用一种创造性的方法，通过基于南极的极光观测来了解白天磁层密度的演变。特别是，南极因其世界上最长的极夜而成为理想的日间极光观测站。产生哨声模式波的波粒相互作用将被用作利用相关的南极全天极光成像仪和 THEMIS 航天器观测对日侧等离子体密度结构进行成像的工具。这项研究不仅可能影响其本身的漫射极光研究领域，而且可能影响日侧磁层动力学、波粒相互作用和等离子体波激发等相关领域。这项有趣且重要的科学研究提供了一个理想的机会来培养研究生、进一步在南极洲进行科学协作和合作，并创建 THEMIS-南极极光成像仪“日边合流”事件和各自的地磁场测绘结果列表，供科学家使用更广泛的地球空间科学界。