Overview of the Event

On May 29, 1996 the velocity and density of the solar wind were larger than usual and the IMF was strongly northward. Interball, then Polar passed through the northern polar cusp. Interball encountered a field reversing current sheet and then entered the undisturbed magnetosheath through a second current sheet. (Savin et al., 1998). Polar passed through first a thick current sheet interior to the magnetosphere and then moved back and forth across it as it thinned, and Polar approached the reconnection region. (Russell et al., 1998) Observations have been interpreted both as reconnection equatorward of the cusp (Chandler et al., 1999) and poleward of the cusp (Russell et al., 1998; Scudder et al., 1999).

Solar Wind Conditions and Satellite Locations

Figure 1 shows the magnetic field and solar wind dynamic pressure during this event. The field is strongly northward throughout the period and the pressure reaches 8n Pa during the peak of the event. As illustrated in the scaled orbit plot of Figure 2, this pressure causes POLAR to approach but not cross the expected location of the magnetopause. The location of the Interball and Polar spacecraft in the Z-Y and Z-X GSM planes are shown in Figures 3 and 4.

Publications

Russell C. T., J. A. Fedder S. P. Slinker, X-W. Zhou, G. Le, J. G. Luhmann, F. Fenrich, M. O. Chandler, T. E. Moore and S. A. Fuselier Entry of POLAR spacecraft into the polar cusp under northward IMF conditions, Geophys. Res. Lett., 25, 3015-3018, 1998

Savin S. P., et al., The cusp magnetosheath interface on May 29, 1996: Interball-1 and Polar observations, Geophys. Res. Lett. , 28, 2963-2966, 1998

Chandler, M. O., S. A. Fuselier, M. Lockwood, and T. E. Moore, Evidence of component merging equatorward of the cusp, (.pdf file) J. Geophys. Res. 104 2263-22633, 1999.

Scudder, J. D. et al., Fingerprints of reconnection, in preparation, 1999.

Savin, S., et al., IACG Boundary layer campaign: Current status and cluster-II perspectives