To understand further the complex evolution within individual substorms
requires coordinated experimental campaigns such as SUNDIAL. Substorms during
two intervals during the 1987 SUNDIAL campaign were studied using five radars
covering the nightside ionosphere. Despite very different IMF conditions,
the total time from the southward turning of the IMF to the substorm expansion
phase onset was 90 min in both cases studied. Furthermore, the response time of
the ionospheric convection to the southward turning of the IMF, indicative of
the start of the substorm growth phase, increased with MLT from 15 minutes
near 1800 MLT to about 1 hour near midnight MLT.
The ethos of the ISTP has been exploited in a study of a relatively small, simple substorm of 9 March 1995 which occurred after a very long interval of magnetic quiet. The study involves data from WIND, Geotail, IMP-8, DMSP, and LANL satellites, together with ground-based data-sets comes from >70 observatories, and 7 SuperDARN radars. A major reconfiguration of the geomagnetic tail caused by an IMF By change does not cause the substorm to occur immediately, thus favouring an internal trigger for this substorm. Neither Geotail nor IMP-8 shows evidence of significant reconnection occurring in the tail at substorm onset, but some evidence of pinching of the tail field is observed at IMP-8.
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