The impact of ULF waves on radiation belt electrons

During geomagnetic storms relativistic electrons in the Earth's outer radiation belt exhibit highly variable and complex behavior and understanding their dynamics is one of the fundamental questions of contemporary space physics. Previous studies show that one of the primary mechanisms of electron transport and acceleration is radial diffusion induced by wave-particle interaction with ULF waves in the inner magnetosphere. However, there is no consensus about what the diffusion rates are, how they depend on the level of geomagnetic activity or the relative role of diffusion in overall particle dynamics. In this paper we investigate the impact of the inner magnetospheric ULF waves on the outer radiation belt electrons. The study involves theory, data analysis and numerical simulations. We use electromagnetic fields measured by elliptically orbiting CRRES spacecraft to investigate the spatial and temporal development of storm time ULF waves. Acquired wave fields are used to calculate diffusion rates during disturbed geomagnetic conditions and compare them with theoretical estimates.