Dayside Auroral Pulsations and their Association with Outer Magnetospheric Dynamics

地球的磁层不断地与入射的太阳风等离子体流相互作用，将其能量和动量从外层转移到电离层和上层大气。这些物理过程主要发生在地球的日面，在外层磁层产生电磁波，这可能是导致和/或调制导致日面极光脉动的高能电子沉淀的关键因素。为了更好地理解这些隐藏在日侧极光脉动之下的物理过程，有必要研究极光结构变化与日侧外磁层动力学的关系。这一奖项将极大地促进我们对外磁层中的超低频电磁波动力学及其与地球电离层的联系以及在那里发生的各自过程的理解。这项研究的动机是最近的案例研究，表明白天极光脉动的动力学行为与上游起源的地球传播的压缩Pc3波引起的千电子伏特电子沉淀之间的联系。本研究将对上述假设情景进行第一次关键的观测测试，通过在二维视角下表征日侧极光脉动的时空特性，这将有助于解决它们与外磁层动力学的关系。更具体地说，将解决以下科学问题：(a)白天极光脉动的时空特性是什么，(b)它们的发生率、周期、传播方向以及与极地地区地面观测到的地磁脉动的相关性是什么。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Earth's magnetosphere interacts continuously with the incoming solar wind plasma flow, transfers its energy and momentum from outer layers down to the ionosphere and upper atmosphere. These physical processes take place mainly on the Earth's dayside, generating electromagnetic waves in the outer magnetosphere that likely act as key agents in causing and/or modulating precipitation of energetic electrons responsible for the dayside auroral pulsations. For better understanding of these physical processes laying underneath the dayside auroral pulsations, it is essential to examine associations of the auroral structure variations with the dayside outer magnetospheric dynamics. This award will significantly advance our understanding of the ultra-low frequency electromagnetic wave dynamics in the outer magnetosphere and their connection to the Earth's ionosphere and respective processes taking place there. This research was motivated by recent case studies that suggested connections between the dynamical behavior of daytime auroral pulsations being modulated by the kilo-electron-volts electron precipitation caused by the earthward-propagating compressional Pc3 waves of the upstream origin. This study will conduct the first critical observational test of the above hypothetical scenario via characterization of spatiotemporal properties of the dayside auroral pulsations in the two-dimensional perspective that will help addressing their association with the dynamic of outer magnetosphere layers. More specifically, the following science questions will be addressed: (a) what are the spatiotemporal properties of the dayside auroral pulsations, and (b) what are their occurrence rate, period, propagation direction, and correlation with the geomagnetic pulsations observed from the ground in the polar regions.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.