Non-Migrating Thermospheric Tides Shift and Deform the Solar Quiet Current Vortex Over Asia

Abstract

Variations in the Solar quiet (Sq) current are typically attributed to the changes in atmospheric tides. In this study, we analyzed the ground-based observations of the geomagnetic field to investigate the morphology of the Sq current over Asia (from 130° to 70°E). The analysis shows that the Sq current vortex deforms into a tilted ellipse over East Asia as it moves northwestward, which is more complex than previously thought. We also estimated the current generated by the polarized electric field (J_Ep) in the E-region from the non-migrating tidal winds of TIMED/TIDI (TIMED Doppler Interferometer on board the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite). The estimation is a qualitative approximation based on the fundamental polarization concept. We used the Observing Procedure Experiment (OPE) to reconstruct the Sq current and to evaluate its deformation and movement deviating from the geomagnetic equator. The results show that J_Ep can contribute to the shift and deformation of the Sq current. The observation and estimation indicate that the ionospheric current system modulated by winds blowing nonuniformly causes complex variations in the E-region dynamo over Asia. This study additionally attempts to simulate the Sq vortex from the Thermosphere Ionosphere Electrodynamics General Circulation Model. Similarities and differences between the simulation and the observation are also discussed.