The development of the magnetospheric substorm and its influence on the magnetopause motion

The time development of the magnetospheric substorm on February 10, 1997 and its influence on motion of low-latitude magnetospheric boundary was studied. The plasma and magnetic data obtained on 4 spacecraft (WIND, Interball-1, Geotail, GOES 8) are compared to measurements at ground based stations. The observations show that the release of energy stored in the magnetotail was initiated by tail current disruption in the near-Earth region and that neutral line formation occurred a few minutes after the tail current disruption. Almost simultaneously with the substorm onset, a series of four rapid magnetopause crossings was observed by the Interball-1 on the evening flank of low-latitude magnetosphere. Some of the possible causes of the observed magnetopause motion, such as variations of the solar wind parameters, the Kelvin-Helmholtz instability and substorm processes are considered in the paper. The fast magnetopause motion is observed almost simultaneously with magnetic field variations in the near-Earth magnetotail and geomagnetic Pi2 pulsations on the ground. The results suggest the possible connection of short-time motion of the magnetospheric boundary with tail current disruption and the substorm current wedge formation.