Solar energetic particles and the configuration of the magnetosphere

Since the original study of PCA riometer measurements, solar energetic particles have been increasingly employed as test particles in the magnetosphere. The characteristics of the access of these particles to the magnetosphere are studied to determine if substantial connection exists between the earth’s dipole field and the solar‐generated interplanetary field. Satellite measurements over the polar caps indicate strong north pole‐south pole proton flux asymmetries that may be related to existing interplanetary particle anisotropies. High‐latitude measurements indicate significant pseudo‐trapping of the solar fluxes on closed magnetospheric field lines. Particle flux comparisons between satellites in interplanetary space and within the magnetosphere suggest that the particle access point is probably not greater than 1000 R E (earth radii) behind the earth in the magnetotail.