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

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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.