Characteristics of the equatorward auroral boundary near midnight determined from DMSP images

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Abstract
The latitude of the equatorward auroral boundary near local midnight has been determined for 162 Defense Meteorological Satellite Program (DMSP) images in November‐December 1972. When grouped according to Kp and AE, these observations show approximate linear decreases in the average boundary latitude with increasing values of these magnetic indices. There appears also to be a slight diurnal variation in the boundary location. Mapping of the appropriate McIlwain injection boundaries to auroral latitudes shows good agreement with the average DMSP equatorward auroral boundary latitude. Similar analyses at 2000 and 2200 CGLT (corrected geomagnetic local time) using a different set of DMSP images yield similar results, with somewhat poorer agreement under quiet conditions.