Properties of Meso-scale Polar Cap Structures and their Coupling to Nightside Auroral Dynamics

太阳风与地球磁场的耦合对地球附近的空间环境产生了一系列扰动效应。 通信、导航以及能源生产和分配可能会受到这种太空天气的显着影响。预测可能影响这些技术的扰动的能力取决于对相连的日地系统的详细了解和理解，包括磁层和电离层之间复杂的耦合过程。后者的一个特殊方面是在极冠中观察到的极光发射斑块和弧。最近的一些研究表明，这些起源于白天的结构可以漂移穿过极冠，并在夜间电离层空间天气扰动的产生和动态中发挥作用。 确定这些极冠结构的精确性质及其与夜间电离层和磁层其他动态特征的关系是该项目的主要目标。 将通过对来自各种来源的相关现象的同时观察进行综合分析来尝试。 由此产生的理解构成了能够将这种效应纳入电离层空间天气规范和预报模型的关键一步。 作为研究工作的一部分，一名研究生将接受培训。该项目旨在确定极帽斑块和极弧的特性及其与极光增强（PBI）和流光的统计关联。 Airglow 630.0 nm 成像仪将用于跟踪极帽结构并确定极帽斑块之前的 PBI 部分，以及导致 PBI 的极帽斑块部分。极帽斑块/弧的特性（例如尺寸和速度）将通过雷达测量确定，并通过共轭航天器确定相应的波瓣测量（流量、颗粒、FAC 结构）。 研究工作的具体项目目标包括：(1) 建立统计上的气辉/电弧-PBI 连接，(2) 确定极冠中中尺度结构的特性，以及 (3) 为电离层流动通道建立可能的磁层对应物。

The coupling of the solar wind with Earth's magnetic field gives rise to a range of disturbance effects in the space environment near Earth. Communications, navigation and energy production and distribution can be significantly affected by this space weather. The ability to forecast disturbances that may impact these technologies hinges upon detailed knowledge and understanding of the connected Sun-Earth system, including complicated coupling processes between the magnetosphere and ionosphere. A particular aspect of the latter is patches and arcs of auroral emissions observed in the polar cap. Some recent studies suggest that these structures, originating on the dayside, can drift across the polar cap and play a role in the creation and dynamics of space weather disturbances in the nightside ionosphere. Determining the precise nature of these polar cap structures and their relation to other dynamic features in the nightside ionosphere and magnetosphere is the main objective of this project. It will be attempted through a comprehensive analysis of simultaneous observations of the relevant phenomena from a variety of sources. The resulting understanding constitutes a critical step towards being able to include this effect in ionospheric space weather specification and forecast models. A graduate student will be trained as part of the research effort. This project aims to determine the properties of polar cap patches and arcs and their statistical association with auroral intensifications (PBIs) and streamers. Airglow 630.0 nm imagers will be used to track polar cap structures and determine the fraction of PBIs that are preceded by polar cap patches, and the fraction of polar cap patches that lead to PBIs. The properties of the polar cap patches/arcs such as size and speed will be determined with radar measurements, and the corresponding lobe measurements (flow, particle, FAC structure) determined with conjugate spacecraft. Specific project goals for the research effort include: (1) Establishing the airglow/arc-PBI connection statistically, (2) Determining the properties of the meso-scale structures in the polar cap, and (3) Establishing the possible magnetospheric counterpart for the ionospheric flow channels.