Samuel Walton

The relativistic (MeV) electron population in the outer Van Allen radiation belt is highly dynamic and strongly coupled to geomagnetic activity such as storms and substorms driven by the interaction of the magnetosphere with the solar wind. Electron content and energy within the outer belt can vary on timescales of hours to days, dictated by the continuously evolving influence of simultaneously occurring acceleration and loss processes. The exact nature and relative significance of each of these processes is highly complex and far from fully understood. Using a continuous 12-year dataset from the Proton Electron Telescope (PET) on board the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX), we statistically examine the relative variation of electron flux in the bounce loss cone in relation to trapped flux. We find that during storm main phase and early recovery phase, there is a proportional increase in flux entering the bounce loss cone outside the plasmapause. Dawn-side loss enhancement is sustained throughout the recovery phase while the post-noon sector is enhanced around minimum Sym-H and quickly diminishes. The detailed MLT-variation of loss is also examined and compared with wave power maps where a possible causal relationship is discussed. These new results reveal important changes in the balance of radiation belt acceleration and loss processes with geomagnetic activity.