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在地球附近的空间环境中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空间天气的重大影响。预测可能影响这些技术的扰动的能力取决于对相互关联的日地系统的详细知识和了解，包括磁层和电离层之间的复杂耦合过程。后者的一个特殊方面是在极冠中观察到的极光发射的斑点和弧形。最近的一些研究表明，这些起源于白天的结构可以漂移到极冠，并在夜间电离层空间天气扰动的产生和动力学中发挥作用。确定这些极冠结构的确切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有关现象的同时观察进行全面分析来尝试这一点。由此达成的谅解是朝着能够将这种影响纳入电离层空间气象规范和预报模式迈出的关键一步。作为研究工作的一部分，一名研究生将接受培训。该项目旨在确定极冠斑块和弧线的性质及其与极光增强和流光的统计联系。气辉630.0 nm成像仪将用于跟踪极帽结构，并确定在极帽补丁之前的极帽斑块的比例，以及导致极帽补丁的极帽补丁的比例。极冠斑块/弧线的性质，如大小和速度，将由雷达测量确定，相应的波瓣测量(流动、颗粒、FAC结构)将由共轭航天器确定。研究工作的具体项目目标包括：(1)从统计上建立气辉/弧光-PBI联系，(2)确定极帽中尺度结构的性质，以及(3)建立可能的电离层流动通道的磁层对应物。

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.