Optical Observations of Interhemispheric Electron Bouncing during Pulsating Aurora

A case study of a pulsating auroral event is presented where rapid optical pulsations are observed with high time resolution. The auroral event occurred over Poker Flat, AK (L = 5.9) on 07 January 2014 and was imaged optically with several different imagers. Immediately following each of the active pulsation times are equally spaced and subsequently fainter pulsations. Both the temporal spacing and the subsequent reduction in optical intensity are evaluated in the context of the inter-hemispheric electron bouncing predicted by the SuperThermal Electron Transport model. These features can be explained by the primary precipitating electrons reflecting upwards from the ionosphere, traveling to the opposite hemisphere and then reflecting upwards again, with the bounce times corresponding to primary electron energies of 6 to 7 keV. The multi spectral imaging data will also be used to estimate these energies with an independent method. The high time-resolution of these data, combined with the short duration of the pulsation (approximately 1 s) and the relatively long spacing between pulsations (around 6 to 9 s) made it possible to observe the faint optical pulses that could be caused by the reflected electrons coming from the opposite hemisphere.