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

Abstract

Abstract. We present a compilation of observations of relativistic radiation belt electrons during the four Geospace Environment Modeling (GEM) storms from instruments on 10 separate spacecraft. While these four magnetic storms have very different solar wind and magnetospheric conditions, there are several characteristics 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 both radial position and the value of the first adiabatic invariant. The evolution of the greater than 1-MeV electron flux at L = 4.2 and L = 6.6 for the 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 relativistic electron events in general.

Science Goals and Overview of the Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) Suite on NASA’s Van Allen Probes Mission

“…Our previous studies have shown evidence for local peaks but were limited by the range of L-shells (e.g. McAdams et al 2001;Chen et al 2005) or by high spacecraft latitudes that limited pitch angle coverage (e.g., Selesnick and Blake 1997;Green and Kivelson 2004). The ECT particles suite (plus magnetic field observations) will provide phase space density gradients over the full range of μ, J , and L * values that are crucial to understand belt dynamics.…”

Features of energetic particle radial profiles inferred from geosynchronous responses to solar wind dynamic pressure enhancements

“…The commonly used method is to convert the flux observed at fixed energy to phase space density at constant first, second and third adiabatic invariants. Many papers have been written on this topic recently Blake, 1997, 2000;Hilmer et al, 2000;McAdams et al, 2001;Green and Kivelson, Y. Shi et al: Features of energetic particle radial profiles 2004; Onsager et al, 2004;Taylor et al, 2004;Iles et al, 2006;Chen et al, 2005Chen et al, , 2007.…”

Online NARMAX model for electron fluxes at GEO

“…The review by Friedel et al (2002) includes all these mechanisms for acceleration. The main candidates are based on either local diffusion due to particle interactions with waves (Temerin et al, 1994;Shprits et al, 2008;Reeves et al, 2009;Omura et al, 2007;Horne et al, 2005;Summers and Thorne, 2003;Summers et al, 1998Summers et al, , 2002Summers et al, , 2004Albert, 2003Albert, , 2005 or radial diffusion (Falthammar, 1968;Schulz and Lanzerotti, 1974;Hilmer et al, 2000;Ingraham et al, 2001;McAdams et al, 2001). …”