A Statistical Study of Pulsating Aurora and its Impact on M-I Coupling

Abstract:

In this presentation we report on initial results to our ongoing study of the source and energy of pulsating aurora (PA). PA are a very common phenomenon. They appear as diffuse patches of aurora that blink on and off with periods up to 20 seconds. In addition, they can be spread over hours of MLT and last for hours. Previous studies have linked them to wave-particle interactions in the outer radiation belt with electrons that have significantly higher energy than other types of aurora. This implies that PA transfer a significant amount of energy into the ionosphere and are likely very important to M-I coupling. To help answer open questions regarding the type of waves that drive PA, their energy spectrum, and the cause of the pulsating behavior, we are conducting a statistical study using multiple instruments. All-sky imagers allow us to visually identify PA, the Poker Flat Incoherent Scatter Radar (PFISR) allows us to extrapolate the upper boundary of precipitating electron energy, and the EMFISIS data from the Van Allen Probes allows us to measure wave activity in the outer radiation belt. So far, the conjunctions we have analyzed between these instruments indicate a strong correlation between PA, lower-band chorus waves, and electrons with energies up to, and in some cases above, 50 keV.