The Auroral Vortex and Rolling Magnetic Carpet

We report a nightside array of cylindrical auroral vortices observed at four wavelengths on 1 January 2024 from Poker Flat, Alaska. A pre-existing east–west arc just south of the site began beading from the west, evolving into curls and then spirals while extending eastward, initiating a substorm expansion within ∼2 min. The vortices were seen in all four wavelengths at 427.8, 557.7, 630.0, and 1100.0 nm, indicating a ∼200 km-tall cylinder spanning 100–300 km altitude. Vortex dimensions were ∼30 × 40 km (east–west × north–south). Estimated average energy and energy flux were 4–6 keV and 30–40 mW/m². The auroral morphology suggests that a remote shear force triggered the Kelvin–Helmholtz instability, generating local vortices that rolled up the magnetic flux like coiling a carpet. Upward field-aligned currents (downward electrons) warped with the rolling magnetic carpet, producing a spiraling auroral footprint in the ionosphere.