Guest Speaker: Lindsay Goodwin, Postdoctoral Associate, Boston University
TITLE: Mesoscale Convection Structures Associated with Polar Cap Patches Characterized using Cluster-Imager Conjunctions
ABSTRACT: Polar cap ionospheric plasma flow studies often focus on large-scale averaged properties and neglect the mesoscale component. However, recent studies have shown that mesoscale flows are often found to be collocated with polar cap patches. These mesoscale flows are typically a few hundred m/s faster than the large-scale background, and are associated with major auroral intensifications when they reach the poleward boundary of the nightside auroral oval. Patches often also contain ionospheric signatures of enhanced field-aligned currents (FACs) and localized electron flux enhancements, indicating that patches are associated with magnetosphere-ionosphere coupling on open field lines. However, magnetospheric measurements of this coupling are lacking and it has not been understood what the magnetospheric signatures of patches on open field lines are. The work presented in this talk explores the magnetospheric counterpart of patches and the role these structures have in plasma transport across the open field line region in the magnetosphere. Using red-line emission measurements from the Resolute Bay Optical Mesosphere Thermosphere Imager, and magnetospheric measurements made by the Cluster spacecraft, conjugate events from 2005 to 2009 show that lobe measurements on field lines connected to patches display: 1) electric field enhancements, 2) region-1 sense FACs, 3) field-aligned enhancements in soft electron flux, 4) downward Poynting fluxes, and 5) in some cases enhancements in ion flux, including ion outflows. These observations indicate that patches highlight a localized fast flow channel system that is driven by the magnetosphere and propagates from the dayside to the nightside, most likely being initiated by enhanced dayside reconnection.
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