Statistical Investigation of Recurrent Substorms/Substorm-like Disturbances in the Magnetotail

Substorms, unlike geomagnetic storms, are more localized and shorter-lived geomagnetic events that occur from interactions between the solar wind and Earth's magnetospheric-ionospheric system. Studying the recurrence of these substorms is an integral window into the dynamics that drive these events. The occurrence, periodicity, and conditions under which they occur are all key aspects of this relationship. The present study explores these processes and delivers preliminary results of a statistical survey of a class of periodic substorms or substorm-like events. Using visual analysis of data from THEMIS satellites, we identified more than 100 recurrent events that satisfied a periodicity of greater than 30 minutes and less than 2 hours. Enhanced plasma flow in the magnetotail and dipolarization of the magnetic field were significant indicators of event occurrence. While some of the events appear to be substorms, a large number appear to be associated with smaller-scale dipolarization fronts. These events were then profiled by Dst (Disturbance Storm Time) and AE (Auroral Electrojet) data collected from the World Data Center for Geomagnetism, Kyoto. It was found that the large majority of these recurrent events occurred at non-storm times, thereby differentiating them from another mode of the magnetosphere: sawteeth. The results of this experiment will allow for a better understanding of magnetotail dynamics and space weather phenomena.