Multisatellite comparisons of the radiation belt response to the Geospace Environment Modeling (GEM) magnetic storms

We present a compilation of observations of relativistic radiation belt ele ctrons during the four Geospace Environment Modeling (GEM) storms from inst ruments on 10 separate spacecraft. While these four magnetic storms have ve ry different solar wind and magnetospheric conditions, there are several ch aracteristics of the relativistic electron response which are applicable to all four storms. We find that although the evolution of the spectral shape of the electrons at a specific L shell does not vary from storm to storm, the evolution is very different at L = 4.2 and L = 6.6. Calculations of the phase space density (PSD) show that the evolution of the PSD depends on bo th radial position and the value of the first adiabatic invariant. The evol ution of the greater than 1-MeV electron flux at L = 4.2 and L = 6.6 for th e four storms is consistent with the findings of Reeves et al. [1998c]. The flux at L = 4.2 peaks quickly after the storm (12 hours), while the fluxes at geosynchronous altitudes take several days to rise. We suggest that the common characteristics identified in the four storms that are the subject of this paper can provide a useful basis for comparisons with other storms and for development of a more complete theoretical description of relativis tic electron events in general.