In the present study, we use the Magnetosphere- Thermosphere-Ionosphere-Electrodynamics General Circulation Model (MTIE-GCM) built by Peymirat et al. [1998]. The MTIE-GCM couples the model of inner-magnetospheric plasma convection of Peymirat and Fontaine
[1994] with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model discussed by Richmond et al. [1992]. Although the MTIE-GCM uses a simple dipole geomagnetic field and thus cannot simulate the influences of magnetic-field reconfiguration proposed by Fejer et al.
[1990], it has an advantage over the RCM used in the earlier fossil-wind studies in that the winds in the MTIE-GCM are calculated using the full three-dimensional dynamical equations
with realistic forcing. Furthermore, in the present study we make an attempt to simulate realistically the expansion and contraction of the polar cap, instead of artificially moving the wind pattern equatorward with respect to a fixed polar cap boundary.