Mapping of ISEE-1 Auroral Electric Fields to the Ionosphere and to the Equatorial Magnetosphere

Abstract

We analyze two strong electric field events observed on ISEE-1 during quiet and moderately disturbed conditions, at distances of a few Earth radii over the auroral ionosphere. These fields were observed over time scales of minutes, and thus have time and spatial scales large compared to previously studied strong electric field events. We interpret the data as quasi-stationary potential electric fields, map the fields to the ionospheric level and to the equatorial magnetotail assuming that magnetic field lines are equipotentials, using the Tsyganenko (1989) magnetic field model, and interpret the mapped electric fields as local E × B plasma flows. We show that the electric field data from close distances to the Earth can be interpreted as local image of the distant -v × B electric field in the magnetotail, and discuss the applicability of this method.