Wave-particle interactions in the earth radiation belts: Modeling, theory, and observations

The dissertations quantifies and models various source and loss mechanisms responsible for the variability of the relativistic electrons in the outer radiation belts. Model results are compared to satellite observations. We first present radial diffusion simulations, ignoring the important local source and treating lifetime as a variable parameter. Comparison of our simulations with the long term observations from CRRES and Akebono satellites show that our radial diffusion model is capable of approximately describing the inner boundary of the outer radiation belt fluxes, the location and magnitude of the peak of fluxes, but fails to reproduce the gradual build up of fluxes observed in the recovery phase of many storms. Our simulations show that radial diffusion is responsible for redistribution of the outer radiation belt relativistic electron fluxes. The data derived lifetimes are on the scale of few days, which is much shorter than plasmaspheric losses due to scattering by hiss waves. This shows that lifetimes outside plasmasphere should be included in simulations.; The results of the radial diffusion simulations were also verified with our computations of the pitch-angle diffusion coefficients due to chorus emissions. We present results of the simulations with a simplified diffusion code which indicate that lifetimes do not have significant radial dependence during storms, provided that waves are present at latitudes above 30 degrees. To estimate the effect of local acceleration and loss we developed a 2-D pitch angle and energy diffusion code. Our simulations show that local acceleration is an important source of the relativistic electrons in the heart of the radiation belts for the storms with enhanced VLF activity. We also show that fast refilling of the slot region during the October, 1990 storm and the formation of a new radiation belt near L=2.5 during the storm, 2003 were due to local acceleration.; To study various feedback mechanisms between acceleration and loss we created a 3-D radiation belt code which incorporates radial, pitch-angle and energy diffusion. Our idealized simulations show that local acceleration and loss as well as radial diffusion may occur simultaneously and on similar time scales. Various feedbacks between losses and radial diffusion; competition between losses and local acceleration; and bi-radial diffusion driven by local source are discussed.; Our simulations show that inclusion of the local acceleration, loss due to various plasma waves, and radial diffusion is required for modeling the variability of the outer radiation belt electron fluxes.