CURRENT-DENSITY MODELS OF THE EASTWARD ELECTROJET DERIVED FROM GROUND-BASED MAGNETIC-FIELD AND RADAR MEASUREMENTS

Correlated studies of the eastward auroral electrojet using EISCAT rad ar data and ground-based magnetic field observations from a meridional chain of five stations have been performed during the years 1987 and 1988. Three different models of current distributions-the line-type, t he current sheet and the parabolic model-have been tested for their ap plicability in estimating the current density of the electrojet. The m odel employing a parabolic cross-section of the current density provid es the best results, both from the magnetic profile and from the compa rison of magnetic field and radar current density estimates. Current e stimates from magnetic field observations are systematically 15% highe r than those from EISCAT readings. This discrepancy has been attribute d to the induction effect.