Core plasmas in space weather regions

In recent years, there has been strong interest in "space weather" owing to increasing recognition of the myriad effects that such phenomena may have on space and even ground systems of considerable importance to man. In this paper, we describe the presence of "core" plasmas in the ionosphere and magnetosphere, which may influence various space weather phenomena. Here core plasmas are defined as plasmas with energies from zero to 50 eV(Horowitz, Rev Geophys., 1987) and originating in the terrestrial ionosphere, We first describe the ionosphere as the basic core plasma region for the overall magnetosphere-ionosphere system. We then describe the principal inner/middle magnetospheric regions-the plasmasphere, ring current, and plasma sheet regions-and how core plasmas from the ionosphere, either with little or with substantial energization, become major components of these magnetospheric regions, which are prime "space weather" regions.