Effects of the solar wind conditions on the global magnetospheric configuration as deduced from data-based field models

The results of data based modeling of the magnetospheric configuration and its response to changes in the solar wind dynamical pressure and the interplanetary magnetic field (IMF) are described. Previous models did not have a pre-defined magnetopause and were calibrated by the Kp index, and therefore did not correctly model the solar wind effects. Models are presented which include the effects of the solar wind-controlled magnetopause, the region 1 and 2 Birkeland currents, and the interconnection of the magnetospheric and solar wind fields at the boundary. They predict the most significant effects of solar wind variation on the global magnetospheric structure. On the dayside, the region 1 Birkeland currents cause major changes of the magnetic configuration as the IMF turns southward. The tail current intensity is controlled mainly by the pressure of the solar wind, although the influence of the southward IMF is clearly seen. The effects of the IMF-induced interconnection field were found to be significant.