Inner magnetosphere currents and their role in the magnetosphere dynamics

The role of inner magnetosphere currents in the magnetopause dynamics is an alyzed. The change of magnetopause position under the influence of inner ma gnetosphere magnetic field sources is analyzed. It is shown that the main s ource of such change may be an effective eastward ring current flowing near the inner edge of the plasma sheet. This current produces negative equator ial magnetic field disturbance in the near tail region and can be considere d as one of the main elements of substorm dynamics explaining substorm begi nning deep in the magnetosphere not far from the geostationary orbit. (C) 1 999 Elsevier Science Ltd. All rights reserved.