MORPHOLOGY OF HIGH LATITUDE GEOMAGNETIC DISTURBANCE AND CORRELATIONS WITH SATELLITE MAGNETIC FIELD MEASUREMENTS.

Arctic magnetograms were investigated in order to obtain an improved understanding of the morphology of high latitude magnetic disturbance. A comparison of the disturbance on different days shows that the ionosphere currents producing the disturbance are never very different from the DS current pattern but are also never extremely similar to one another. The direction of current across the polar cap is toward the sun in the summer but is rotated about 40 degrees clockwise looking down on the north pole in the winter. Arctic magnetograms were also compared to simultaneous Explorer XII measurements of the magnetic field in the transition region outside the magnetosphere. A southward field measured by the satellite was found to correspond to ground disturbance and a northward field to quiet periods. These results are interpreted as supporting the field reconnection mechanism of Dungey whereby the interplanetary magnetic field becomes attached to high latitude earth dipole lines, thus allowing the solar wind to drive the ionospheric current. Author