On the Statistics of Acceleration and Loss of Relativistic Electrons in the Outer Radiation Belt: A Superposed Epoch Analysis

We investigate the response of the outer Van Allen belt electrons to various types of solar wind and magnetospheric disturbances. We use electron phase space density calculations as well as concurrent Pc5 and chorus wave activity observations in the outer belt during the Van Allen Probes era to compare 20 electron enhancement and 8 depletion events. Results indicate that the combined effect of magnetopause shadowing and outward diffusion driven by Pc5 waves is present in both groups of events. Furthermore, in the case of enhancement events, the synergy of enhanced seed population levels and chorus activity—due to the enhanced substorm activity—can effectively replenish the losses of relativistic electrons, while inward diffusion can further accelerate them. Key Points The number of events with PSD enhancements is L* and μ dependent Loss, as a combined effect of magnetopause shadowing and outward diffusion, is a common feature in both depletion and enhancement events The synergy of enhanced seed population and chorus activity is what distinguishes relativistic electrons enhancements from depletions