Dayside proton aurora associated with magnetic impulse events: South Pole observations

We present, for the first time, auroral hydrogen emission at 486.1 nm (proton aurora) associated with a magnetic impulse event (MIE) or a traveling convection vortex (TCV). The MIE (or TCV) is a transient phenomenon (∼5–15 min) characterized by a large amplitude (>50 nT) in the magnetic field disturbance occurring at 70°–80° magnetic latitudes (MLATs). Optical observations at the South Pole Station (−74.3° MLAT) showed a clear spot‐like brightening of proton auroral emissions associated with MIEs. These spots of the proton aurora were ∼300–500 km in length and ∼150–200 km in width at an altitude of 150 km and lasted for ∼1–2 minutes. The spot drifted antisunward with a speed of ∼3–5 km/s but did not always drift. Quasi‐stable spots coincided with poleward moving multiple arcs at 630.0 nm. There was no clear one‐to‐one correspondence between the spots and the power of the ground magnetic field in the Pc1 range. The variety of proton auroral emissions associated with MIEs may be a visible manifestation of the variety of processes that take place near the region generating a pair of field‐aligned currents that drives MIEs.