Mesoscale Convection Structures Associated With Airglow 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 airglow patches. These mesoscale flows are typically a few hundred meters per second 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 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 here 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 field‐aligned currents, (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 localized dayside reconnection.

Resolving the High‐Latitude Ionospheric Irregularity Spectra Using Multi‐Point Incoherent Scatter Radar Measurements

“…Plasma density depletions, such as polar holes, can also result through transportation (Forsythe et al., 2021; Sojka et al., 1981a, 1981b), but also result through enhanced plasma recombination (Perry et al., 2015; Zettergren & Semeter, 2012). The drivers of these processes, such as magnetospheric coupling (Goodwin et al., 2019), determines the size and occurrence of ionospheric irregularities. Therefore, by quantifying the scale‐sizes of plasma density variations in the ionosphere we can better understand the generation mechanisms of irregularities, as well as the dynamics and energy deposition of the high‐latitude ionosphere.…”