The primary coupling between the magnetosphere and the ionosphere is accomplished via electric currents flowing along the Earth's magnetic field. Upward current regions generally result from downward flowing electrons which have been observed with many satellites. In contrast, downward current regions generally involve upward flowing electrons that have been more difficult to observe. Thus our outstanding of the downward current regions has lagged behind our understanding of the upward current regions. This study will develop a self-consistent picture of the plasma and field properties of downward auroral current regions. The results will lead to a better understanding of such features as ion conic particle distributions, downward pointing electric fields and ELF/VLF turbulence. The theoretical underpinning of the study will be to break the problem into two separate but coupled problems with vastly different time scales. ELF/VLF turbulence operates on times scales of milliseconds, while the evolution of the large-scale auroral current structures takes place on time scales of minutes to hours. Thus a self-consistent high frequency spectrum can be determined in the context of a slowly evolving background distribution.
