Quantification of the Error in Radiation Belt Electron PSD due to Global Field Model Errors

Friday, 9 March 2018: 15:50
Longshot and Bogey (Hotel Quinta da Marinha)
Adam C Kellerman1, Yuri Shprits2,3, Dmitri A Kondrashov4 and Alexander Drozdov2, (1)University of California Los Angeles, Department of Earth, Planetary and Space Sciences, Los Angeles, CA, United States, (2)University of California Los Angeles, EPSS, Los Angeles, CA, United States, (3)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, (4)University of California Los Angeles, Los Angeles, CA, United States
Abstract:
In recent years there has been a community wide move towards utilizing electron phase space density (PSD) for objective analysis of radiation belt dynamics, in both observational and modeling studies. Until now though, there has not been a quantitative analysis of the errors introduced to electron PSD across several L-shells as a result of global field model errors. This is largely due to the enormous computational requirement for such an analysis. Past studies have been focused largely on geosynchronous orbit, on particular years, on scalar or particular components of the B-field, and/or on particular storm periods. The results of these analyses can not be readily extended to other L-shells and other times, as dynamics can change significantly between events, solar-cycle phase, and between different solar cycles.

In the current study, an analysis of over 27 years of data and B-field model computations are presented for the purpose of quantifying the errors in electron PSD. Presented are statistical errors in the scalar B field, equatorial pitch angle, energy, in all three invariants, and in electron PSD. The errors in the first invariant, pitch angle, and energy are computed directly, while the errors in the second two invariants are determined by (a) the variability in B, K and L* across several B-field models, and (b) a projected/estimated error based on incorrect determination of the equatorial pitch angle due to an error in the modeled B-field.

The analyses are conducted as a function of radial distance to the magnetic equator (in the T89, T96, T02, T03, TS05, and TS07D models), MLT, quiet time, storm time, and storm phase as determined by the Sym-H index. For each location in radial distance and MLT, and for each time point, the errors in each of these quantities is determined, and transformed into errors in PSD using the actual/estimated profiles of electron PSD at each time point. The results of this analysis are directly applicable to studies of radiation belt dynamics from single spacecraft, multiple spacecraft, and radiation belt simulations. The results are also useful for satellite PSD matching, and data assimilation. An application of the results to the latter two is presented and discussed.

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