An Examination of Ionospheric Flow Dynamics During a SAR Arc - STEVE Event

Strong Thermal Emission Velocity Enhancement (STEVE) and Stable Auroral Red (SAR) arc are two distinctive features of the sub-auroral ionosphere. STEVE events are associated with "extreme" Subauroral Ion Drifts (SAIDs) with speeds over 4-5 km/s, whereas SAR arcs are primarily linked to magnetospheric heat conduction. Previous studies have shown that SAR arcs can also be linked with heating associated SAIDs in the mid-latitude trough region. More recent observations have shown that SAR arcs can occur in the vicinity of STEVE, often times prior to STEVE's occurrence. However, the exact nature of the relationship between STEVE and SAR arcs remains poorly understood. In particular, we are yet to understand how plasma convection in the sub-auroral region varies during SAR arc - STEVE sequence events. In this study, we examine sub-auroral ionospheric flow dynamics during a SAR arc - STEVE - SAR arc sequence event observed on April 10, 2022 by the all sky imager in Lucky Lake, Canada. During this event interval, the US mid-latitude SuperDARN radars were making continuous observations of plasma convection collocated with the observations made by the Lucky Lake all sky imager. We analyze the temporal variability in speed, direction, and latitudinal extent of sub-auroral plasma convection during the SAR arc - STEVE - SAR arc sequence event to test and validate our current understanding of inner magnetosphere-ionosphere coupling during such intervals.