Effects of Subauroral Polarization Streams on the Equatorial Electrojet During the Geomagnetic Storm on June 1, 2013

In this work, the effect of disturbance dynamo electric field (DDEF) induced by subauroral polarization streams (SAPS) on the variations of the equatorial electrojet (EEJ) and its counter electrojet (CEJ) during the geomagnetic storm on June 1, 2013 is analyzed in detail for the first time. Observations from ground-based magnetometers showed that the SAPS-induced EEJ flows westward and eastward in the daytime and dawn/dusk sectors, respectively. The effects of SAPS on EEJ are mainly associated with the changes of zonal ionospheric electric field, while the changes in the ionospheric conductivity play a secondary role. By using Thermosphere Ionosphere Electrodynamic General Circulation Model simulations, the zonal electric field induced by SAPS associated with the DDEF is examined. The results of the simulations show that the DDEF has a significant impact on the EEJ variability. The daytime westward EEJ at the dip equator is mainly driven by disturbance zonal wind, with secondary contributions from disturbance meridional wind. A similar mechanism can be observed in the dawn/dusk sector when the eastward EEJ is produced; however, it has a much weaker intensity than that during the daytime.