Effects of Subauroral Polarization Streams on the Equatorial Electrojet During the Geomagnetic Storm on June 1, 2013. Part II: the temporal variations

Using ground-based magnetic field measurements and numerical simulations from the Thermosphere-Ionosphere Electrodynamic General Circulation Model (TIEGCM), a first paper (Zhang et al., 2021b, under review) introduced the potential roles of disturbance dynamo electric field due to subauroral polarization streams (SAPS) on the equatorial electrojet (EEJ) during a moderate geomagnetic storm on June 1, 2013. Our second study investigated the temporal responses of equatorial electrojet to SAPS. At noon, the residual EEJ (ΔEEJ) owing to SAPS flows westward, that is, counter equatorial electrojet (CEJ). The temporal variation of CEJ excited by the dynamo electric field was basically consistent with that by SAPS, and the effects of zonal wind were larger than those of meridional wind. The relative time delay of CEJ and SAPS was related to the propagation time of disturbance wind from mid-latitudes to low-latitudes. It took 2-3 h for SAPS-related disturbance wind to propagate to the equatorial region and change the polarity of EEJ. The influence of meridional winds on the temporal variations of ΔEEJ is related to the generation of eastward currents at mid-latitudes, which can accumulate the positive charges at dusk terminator and then generate a westward electric field at lower latitudes.