Regional, scale size, and interplanetary magnetic field variability of magnetic field and ion drift structures in the high‐latitude ionosphere

Abstract

Using data from the Dynamics Explorer 2 satellite's ion drift meter and magnetometer, we have examined fluctuations in the high‐latitude velocity and magnetic field structure to better understand the coupling between the magnetosphere and ionosphere. Our study examines perturbations in the frequency range from 0.25 to 8 Hz, equivalent to static scale sizes between about 30 and 1 km. Seasonal variations in the perturbations at large‐scale sizes indicate that magnetosphere‐ionosphere coupling is dominated by static currents. These static currents display behavior consistent with a current driver in the auroral zone and a voltage driver in the cusp. In the frequency range 0.6 to 1.5 Hz the magnetosphere‐ionosphere coupling is significantly influenced by Alfven waves with the high‐frequency range extending up to 8 Hz in the cusp.