| dc.description.abstract | Abstract Model results of Huang et al. [2005], using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) to investigate the influence of geomagnetic activity on middle- and low-latitude thermospheric winds and ionospheric electric fields, indicate that that the equatorward current, produced by the disturbance winds, develops positive charge accumulation at low latitudes and maximizes in the premidnight sector. We may find the eastward perturbation electric field in the post-midnight sector and existence of poleward perturbation electric field at night time. After geomagnetic activity ceases, model results show that the meridional perturbation electric fields can last for many days in the post-recovery period, while the zonal perturbation electric fields decay more rapidly. In this thesis, two velocity components orthogonal to the geomagnetic field line, i.e., meridional component (V2m) and zonal component (V2z) are used to study the variations of equatorial iobospheric electric fields during and after the storm time. In addition, comparisons between model results and observational data have also been made. | en_US |