MAPPING OF THE STATISTICAL AURORAL DISTRIBUTION INTO THE MAGNETOSPHERE

Statistical auroral distributions are used in combination with an empi rical model of the Earth's magnetic field in an attempt to determine t he large-scale magnetospheric source regions for various types of auro ral luminosity. The narrow ring of structured auroral emissions during magnetically quiet intervals appears to be associated with the inner region of the nightside central plasma sheet and the dayside entry lay er. Under active conditions these discrete structures expand to fill t he entire central plasma sheet. The high-altitude boundary plasma shee t on the other hand is more likely to be related to diffuse auroral em issions poleward of this ''oval'' and to high-latitude polar auroral a rcs. Under this scenario, the region of the magnetosphere bounded by t he inner edge of the tail current sheet, the plasmasphere, and the day side entry layer is the source region for the most equatorward diffuse auroral precipitation.