Ring Current Effect on Magnetospheric Electron Density Profiles derived from Plasmapause Whistlers

THE longitudinal drift of van Allen radiation belt charged particles, with opposite charges drifting in opposite directions in the geomagnetic field, constitutes a westward directed ring current at a distance of several Earth radii 1 . Although at magnetically quiet times this current scarcely neither reduces the geomagnetic field nor affects the parameters that determine the group velocity of a whistler mode signal propagating along a particular field line, these can be significantly changed at magnetically active times, for example during the main and recovery phases of a magnetic storm, when the ring current is stronger 2 .