Alfven Waves in the Solar Wind and Their Impact on Relativistic Electron Fluxes in the Magnetosphere

In recent years, there has been considerable debate on the origin of enhanced relativistic electron fluxes at geostationary orbit. Several different mechanisms have been suggested for in situ acceleration of these electrons at or around geostationary orbit. In this paper we argue that sometimes the rises and falls of these electron fluxes can merely reflect changes in the tail-like character of the earth's magnetic field when an observing spacecraft makes measurements at different positions on the radial gradients in particle fluxes associated with the trapping boundaries for the specific energies being detected. We find that the solar wind dynamic pressure affects both changes and the absolute values of the measured electron fluxes. We also find that unusually high fluxes of relativistic electrons can arise at geostationary orbit without any magnetic storm involvement. Such cases are accompanied by Alfven waves in the interplanetary medium of the type often associated with so-called HILDCAA events in the auroral oval. We find that this specific feature of the solar wind is associated with a significant number of the relativistic electron flux increases presently attributed to some sort of internal acceleration process in the magnetosphere.