Electrodynamics surrounding polar cap auroral arcs

This multi-instrument case study investigates the electrodynamics surrounding polar cap auroral arcs. A long-lasting auroral arc is observed in the high latitude dusk-sector at ~80° Apex latitude in the northern hemisphere. Ion drift measurements from the SSIES system on the DMSP spacecraft have been combined with multiple ground-based observations. Line of sight velocity data from three polar latitude high-frequency Super Dual Auroral Radar Network (SuperDARN) radars show mesoscale structure in the ionospheric convection in the region surrounding the arc. The convection electric field in this region is modelled using a Spherical Elementary Convection Systems (SECS) technique, using curl-free basis functions only. The result is a regional model of the ionospheric convection based on the fairly dense and distributed flow observations and the curl-free constraint. The model is compared to optical data of the auroral arc from two high latitude Redline Emission Geospace Observatory (REGO) all-sky imagers as well as UV images and particle measurements from the DMSP spacecraft to describe the local electrodynamics in the vicinity of the high latitude arc throughout the event.