Investigating the simultaneous occurrence of STEVEs and SAR arcs using all-sky imagers, satellites, and citizen scientist data

Abstract:

Typical optical observations at sub-auroral latitudes consisted for a long time of stable auroral (SAR) red arcs. A newly discovered optical phenomenon, named STEVE (Strong Thermal Emission Velocity Enhancement), has been observed at similar latitudes and is bringing a renewed interest in studying the generation and evolution of these optical phenomena. STEVEs are thinner than SAR arcs, their lifetimes are much shorter, are visible with the naked eye, and are observed at multiple wavelengths. The appropriate conditions for STEVE generation are not fully understood. In this work we use a sub-auroral all-sky imager and images from auroral citizen scientists to investigate STEVEs and SAR arcs. We also use SWARM and DMSP satellite data to identify SAPS and SAIDs by measuring electron temperature, ion density, and horizontal plasma flow. These parameters are then compared with the optical observations. STEVE and SAR arc were observed during the 17 March 2015 geomagnetic storm and here we discuss how they are related.