A Comparison of Radial Diffusion Coefficients in 1‐D and 3‐D Long‐Term Radiation Belt Simulations
Allison, H. J.
Shprits, Y. Y.
Elkington, S. R.
Aseev, N. A.
DOI: https://doi.org/10.1029/2020JA028707
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9809
Shprits, Y. Y.; 1 University of California Los Angeles Los Angeles CA USA
Elkington, S. R.; 5 Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder CO USA
Aseev, N. A.; 3 GFZ German Centre for Geosciences Potsdam Germany
Abstract
Radial diffusion is one of the dominant physical mechanisms driving acceleration and loss of radiation belt electrons. A number of parameterizations for radial diffusion coefficients have been developed, each differing in the data set used. Here, we investigate the performance of different parameterizations by Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Brautigam et al. (2005), https://doi.org/10.1029/2004ja010612, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, Ali et al. (2015), https://doi.org/10.1002/2014ja020419; Ali et al. (2016), https://doi.org/10.1002/2016ja023002; Ali (2016), and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 on long‐term radiation belt modeling using the Versatile Electron Radiation Belt (VERB) code, and compare the results to Van Allen Probes observations. First, 1‐D radial diffusion simulations are performed, isolating the contribution of solely radial diffusion. We then take into account effects of local acceleration and loss showing additional 3‐D simulations, including diffusion across pitch‐angle, energy, and mixed diffusion. For the L* range studied, the difference between simulations with Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 parameterizations is shown to be small, with Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344 offering the smallest averaged (across multiple energies) absolute normalized difference with observations. Using the Ali et al. (2016), https://doi.org/10.1002/2016ja023002 parameterization tended to result in a lower flux than both the observations and the VERB simulations using the other coefficients. We find that the 3‐D simulations are less sensitive to the radial diffusion coefficient chosen than the 1‐D simulations, suggesting that for 3‐D radiation belt models, a similar result is likely to be achieved, regardless of whether Brautigam and Albert (2000), https://doi.org/10.1029/1999ja900344, Ozeke et al. (2014), https://doi.org/10.1002/2013ja019204, and Liu et al. (2016), https://doi.org/10.1002/2015gl067398 parameterizations are used.
Key Points:
3‐D simulations using different radial diffusion coefficients, except Ali et al. (2016), produce similar results.
Using Ali et al. (2016) DLL, simulated flux is significantly lower than observations.
3‐D modeling with Brautigam and Albert (2000) DLL results in a slightly smaller normalized difference (averaged over energies) to observations.