Drozdov A. Y., Y. Y. Shprits, N. A. Aseev, A. C. Kellerman, G. D. Reeves, (2017), Dependence of radiation belt simulations to assumed radial diffusion rates tested for two empirical models of radial transport, Space Weather, 15, 150-162, doi:10.1002/2016SW001426

Abstract

Abstract 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. We investigate the sensitivity of the two parameterizations of the radial diffusion of Brautigam and Albert (2000) and Ozeke et al. (2014) on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB). Following Brautigam and Albert (2000) and Ozeke et al. (2014), we first perform 1-D radial diffusion simulations. Comparison of the simulation results with observations shows that the difference between simulations with either radial diffusion parameterization is small. To take into account effects of local acceleration and loss, we perform 3-D simulations, including pitch angle, energy, and mixed diffusion. We found that the results of 3-D simulations are even less sensitive to the choice of parameterization of radial diffusion rates than the results of 1-D simulations at various energies (from 0.59 to 1.80 MeV). This result demonstrates 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 perform a number of sensitivity tests by multiplying radial diffusion rates by constant factors and show that such an approach leads to unrealistic predictions of radiation belt dynamics.

Authors (sorted by name)

Aseev Drozdov Kellerman Reeves Shprits

Journal / Conference

Space Weather

Acknowledgments

The authors used geomagnetic indices provided by OMNIWeb (http://omniweb.gsfc.nasa.gov/form/dx1.html) and are grateful to the RBSP‐ECT team for the provision of Van Allen Probes observations (http://rbsp‐ect.lanl.gov/). We would like to thank Dmitry Subbotin, Ksenia Orlova, and Hui Zhu for the useful discussion of the simulation details. We would like to acknowledge high‐performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by UCAR's Computational and Information System Laboratory, sponsored by the National Science Foundation and other agencies. This research was supported by NASA award NNX13E34G and NSF GEM AGS‐1203747 and received funding support from the UC Office of the President, UC Lab Fees Research Program grant 12‐LR‐235337, and Horizon 2020 award 637302.

Grants

12-LR-235337 637302 AGS‐1203747 NNX13E34G Yellowstone

Bibtex

@article{doi:10.1002/2016SW001426,
author = {Drozdov, A. Y. and Shprits, Y. Y. and Aseev, N. A. and Kellerman, A. C. and Reeves, G. D.},
title = {Dependence of radiation belt simulations to assumed radial diffusion rates tested for two empirical models of radial transport},
year = {2017},
journal = {Space Weather},
volume = {15},
number = {1},
pages = {150-162},
keywords = {radiation belts, radial diffusion, VERB code},
doi = {10.1002/2016SW001426},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016SW001426},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016SW001426},
abstract = {Abstract 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. We investigate the sensitivity of the two parameterizations of the radial diffusion of Brautigam and Albert (2000) and Ozeke et al. (2014) on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB). Following Brautigam and Albert (2000) and Ozeke et al. (2014), we first perform 1-D radial diffusion simulations. Comparison of the simulation results with observations shows that the difference between simulations with either radial diffusion parameterization is small. To take into account effects of local acceleration and loss, we perform 3-D simulations, including pitch angle, energy, and mixed diffusion. We found that the results of 3-D simulations are even less sensitive to the choice of parameterization of radial diffusion rates than the results of 1-D simulations at various energies (from 0.59 to 1.80 MeV). This result demonstrates 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 perform a number of sensitivity tests by multiplying radial diffusion rates by constant factors and show that such an approach leads to unrealistic predictions of radiation belt dynamics.}
}