Simulating the Earth\textquoterights radiation belts: Internal acceleration and continuous losses to the magnetopause
Author  
Keywords  
Abstract 
In the Earth\textquoterights radiation belts the flux of relativistic electrons is highly variable, sometimes changing by orders of magnitude within a few hours. Since energetic electrons can damage satellites it is important to understand the processes driving these changes and, ultimately, to develop forecasts of the energetic electron population. One approach is to use threedimensional diffusion models, based on a FokkerPlanck equation. Here we describe a model where the phasespace density is set to zero at the outer L* boundary, simulating losses to the magnetopause, using recently published chorus diffusion coefficients for 1.5<=L*<=10. The value of the phasespace density on the minimumenergy boundary is determined from a recently published, solar winddependent, statistical model. Our simulations show that an outer radiation belt can be created by local acceleration of electrons from a very soft energy spectrum without the need for a source of electrons from inward radial transport. The location in L* of the peaks in flux for these steady state simulations is energy dependent and moves earthward with increasing energy. Comparisons between the model and data from the CRRES spacecraft are shown; flux dropouts are reproduced in the model by the increased outward radial diffusion that occurs during storms. Including the inward movement of the magnetopause in the model has little additional effect on the results. Finally, the location of the lowenergy boundary is shown to be important for accurate modeling of observations.

Year of Publication 
2014

Journal 
Journal of Geophysical Research: Space Physics

Volume 
119

Number of Pages 
74447463

Date Published 
09/2014

URL 
http://doi.wiley.com/10.1002/jgra.v119.9http://doi.wiley.com/10.1002/2014JA020092

DOI 
10.1002/jgra.v119.910.1002/2014JA020092
