Rainbow of the Night: First Direct Observation of a SAR Arc Evolving Into STEVE

During the 17 March 2015 geomagnetic storm, citizen scientist observations from Dunedin (45.95°S, 170.32°E), New Zealand, revealed a bright wide red arc known as stable auroral (SAR) evolving into thin white-mauve arc, Strong Thermal Emission Velocity Enhancement (STEVE). An all-sky imager at Mount John Observatory (43.99°S, 170.46°E), 200 km north of Dunedin, detected an extremely in 630.0 nm, with peak ?6 kR, colocated measured assumed height 425 km. Swarm satellite data plasma parameters that showed strong subauroral ion drift signatures when SAR was observed. These conditions intensified to high values thinner channel STEVE present. Our results highlight fast evolution properties and their effects on optical emissions. Current theories models are unable reproduce or explain these observations.