GROSS DEFORMATION OF THE DAYSIDE MAGNETOPAUSE

On July 24, 1996, the entire magnetosheath moved past the Interball-1 spacecraft twice within 7 min. Such rapid transits through the magneto sheath suggest the passage of an antisunward-moving boundary wave with an amplitude in excess of 5 R-E. A wave of this amplitude requires an order of magnitude decrease in the pressure confining the magnetosphe re. Such decreases have been reported only in conjunction with hot flo w anomalies, features accompanying interplanetary magnetic field disco ntinuities, bounded by narrow shocks, and identified on the basis of h eated deflected flows transverse to the Earth-Sun line. We identify al l these features just outside the Interball-1 magnetopause crossings o n July 24, 1996.