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Dependence of radiation belt simulations to assumed radial diffusion rates

Radial diffusion is one of the dominant physical mechanisms that drives acceleration and loss of the radiation belt electrons, which makes it very important for nowcasting and forecasting space weather models. Comparison of the simulation results with observations showed that the difference between simulations with different radial diffusion parameterization is smaller than the inclusion of local acceleration and pitch angle diffusion.

To take into account effects of local acceleration and loss, we performed 3-D simulations, including pitch angle, energy, and mixed diffusion. We found that the results of 3-D simulations are less sensitive to the choice of parameterization of radial diffusion rates than the results of 1-D simulations performed with different radial diffusion rates at various energies (from 0.59 to 1.80 MeV). This result demonstrated that the inclusion of local acceleration and pitch angle diffusion can provide a negative feedback effect, such that the result is largely indistinguishable simulations conducted with different radial diffusion parameterizations. We also performed a number of sensitivity tests by multiplying radial diffusion rates by constant factors and showed that such an approach leads to unrealistic predictions of radiation belt dynamics.

Published reasearch: Drozdov, A. Y., Y. Y. Shprits, N. A. Aseev, A. C. Kellerman, and G. D. Reeves (2017), Dependence of radiation belt simulations to assumed radial diffusion rates tested for two empirical models of radial transport, Space Weather, 14, doi:10.1002/2016SW001426.