Simultaneous electric field changes in the equatorial electrojet in phase with polar cusp latitude changes during a magnetic storm

Abstract

The Doppler frequency of the VHF radar signals backscattered from the drifting ionization irregularities in the equatorial electrojet is proportional to the east-west electric field E_y in the equatorial electrojet. Using the VHF backscatter radar observations at Thumba during the geomagnetic storm of February 16, 1980, it is shown that the decreases and increases of the storm-time electric fields in the equatorial electrojet are completely in phase with the decreases and increases in the mean latitude of the polar cusp region. This observation has important implications for understanding the magnetosphere-ionosphere interactions, particularly the effect of the magnetospheric electric fields on the low latitude ionosphere.