Spatial distributions of the inner radiation belt electrons: A comparison between observations and radial diffusion theory predictions

Abstract

It is well known that the quiet-time electron radiation belts exhibit a two-zone radial structure. Although the inner radiation belt does show dynamic variations during geomagnetically active periods, the stably trapped electrons found in this region are thought to be populated primarily by diffusive transport processes. Recent analyses of the long-term (1984–1987) energetic electron (0.19-3.2 MeV) observations taken at 350–850 km altitude by the OHZORA satellite indicate that the trapped electrons also show local-time variations in pitch angle distributions. We here report the observed L-shell distributions of the energetic electrons and show that they are in good agreement with the azimuthally averaged predictions of the radial diffusion theory (the Salammbo model) for inner zone electron fluxes. We also compare the OHZORA observations with earlier observations as compiled in the NASA empirical radiation belt models.