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

摘要

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.