A study is made of some dynamic implications of our earlier model of large-scale magnetospheric structure, in which the plasma sheet is a collisionless shock wave (Fridman and Voronov, 1993). According to our calculations, the polar boundary of the auroral oval always lies equatorward of the boundary of closed and open field lines. An abrupt enhancement of the global magnetospheric convection electric field is immediately followed by a thinning of the plasma sheet, an increase of its plasma density and by the equatorward displacement of the auroral oval polar boundary. With a decrease of the magnetospheric electric field the plasma sheet expands, and the polar boundary of the auroral oval is pulled nearer to the boundary of closed and open field lines. A typical time of change of the plasma sheet configuration in the distant tail is a few minutes, while the time of displacement of the auroral oval polar boundary amounts to several tens of minutes. ¿ American Geophysical Union 1994