Modeling The Radiation Belt-Using 3D Layer Method Code

The electron flux of the outer radiation belt is highly variable, especially during geomagnetically disturbed times. Nowadays modeling the dynamics of energetic elec-trons is of much interest in space physics. In part, this is because energetic electrons may pose serious potential hazard to orbiting satellites. And relativistic electrons pre-cipitation also constitute an important link between solar activity and global climate variability. In this thesis, we focus on constructing a 3D code to modeling the outer radiation belt electron flux evolutions, and apply it to a specific event to quantitatively analyse the relative roles of different physical mechannisms in this event.A new 3D diffusion code using a recently published layer method has been devel-oped to analyze radiation belt electron dynamics. The code guarantees the positivity of the solution even when mixed diffusion terms are included. Unlike most of previ-ous codes, our 3D code is developed directly in equatorial pitch angle (α0), momentum(p), and L-shell coordinates; this eliminates the need to transform back and forth be-tween (α0, p) coordinates and adiabatic invariant coordinates. Using (α0, p, L) is also convenient for direct comparison with satellite data. The new code has been validated by various numerical tests, and we apply the 3D code to model the rapid electron flux enhancement following the geomagnetic storm on March 17, 2013, which is one of the GEM Focus Group challenge events. An event-specific global chorus wave model,an AL-dependent statistical plasmaspheric hiss wave model, and a recently published radial diffusion coecient formula from Time History of Events and Macroscale Inter-actions during Substorms (THEMIS) statistics are used. The simulation results show good agreement with satellite observations in general, supporting the scenario that the rapid enhancement of radiation belt electron flux for this event results from an increased level of the seed population by radial diffusion, with subsequent acceleration by chorus waves. Our results prove that the layer method can be readily used to model global radiation belt dynamics in three dimensions.