Swarm Observations of Field-aligned Currents Associated with Pulsating Auroral Patches

Abstract:

Using the ground-based optical data from the THEMIS all-sky imager network in conjunction with magnetometers on board the Swarm satellites, we performed a study of in situ field-aligned currents located near the edges of regions of pulsating aurora. A total of nine traversals of Swarm over regions of pulsating aurora identified using THEMIS ASI were studied. We used a satellite-aligned keogram to identify when Swarm was within a patch of pulsating aurora. A downward current in the range of ~1-6 μA/m² can be seen just poleward of the boundary. A weaker upward current of ~1-3 μA/m² is observed throughout the interior of the patch. The existence of these currents has been reported before but their magnitudes have not been quantified. In this study we quantify the magnitudes, in some cases by using two satellites traversing the same pulsating regions. We also compared Swarm’s two-satellite FAC product to the single-satellite results and determine that the data product can be compromised in regions of pulsating aurora, a phenomenon that occurs over widespread regions and tends to persist for hours. Acknowledgements: This research was supported by an ESA Living Planet Fellowship and various CSA grants.