A Statistical Study of Pulsating Aurora using THEMIS All-sky Ground Imagers

Pulsating aurora is a common phenomenon that occurs primarily in the aftermath of substorms where dim, long period pulsating patches appear. Previous studies on pulsating aurora have used minimal data sets to investigate pulsation periods and MLAT distribution. None of these studies were based on very large data sets, as we now have available. In this study, which includes over half a year of optical data, we determine occurrence rates of pulsating aurora in terms of magnetic latitude and local time, pulsating auroral onsets at different stations to show temporal evolution, relationship to substorms, etc. Preliminary results obtained from the Gillam All-Sky Camera (66°N, 327°E) over 119 days with good optical data beginning September 2007 through the end of March 2008, 74 of which contain pulsating aurora, include: 31.48% of all clear optical data exhibits pulsating aurora, 68.75% of all optically observed pulsating aurora onsets occur post substorm breakup, and a greater likelihood for observing pulsating aurora after midnight (54% probability versus a 14% probability before midnight)