Reanalysis of relativistic radiation belt electron phase space density using multisatellite observations: Sensitivity to empirical magnetic field models

Abstract

Using empirical external magnetic field models (T89, T96, T01s, and T04s) and simultaneous observations from four satellites (CRRES, Akebono, and two GEO satellites) during a 7-day period from 1 to 7 August 1991, we performed a combined reanalysis of radiation belt electron phase space density (PSD). While precise L* locations of the satellites are sensitive to the adopted magnetic field model, comparisons between the reconstructed radial profiles of electron PSD, obtained using Kalman filtering, indicate that the combined reanalyses are relatively insensitive to the choice of the magnetic field model during geomagnetically quiet or moderate activity times or for the long-term reanalysis studies. The reanalysis results using the four external magnetic field models show similarities in the locations of peaks in radial profiles of PSD and the radial extent of the dropouts. The largest difference between assimilated PSD using different Tsyganenko models occurs mostly during geomagnetically active periods when the Dst index is low or at higher L* shells near the boundary. Presented results also suggest that the errors of assimilated PSD based on multiple satellite measurements can become smaller than errors of PSD reconstructed from individual satellites. Copyright 2009 by the American Geophysical Union.