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			 **   THE GEM MESSENGER   **
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						     Volume 7, Number 28
						     July 10, 1997

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     Final Report: GEM Boundary Layer Campaign, Working Group 2
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     From: Chris Russell (ctrussell at igpp.ucla.edu)
     
          The first campaign of the GEM program was devoted to understanding the
     coupling between the solar wind and the magnetosphere as manifested at the
     magnetopause, in the boundary layers surrounding the magnetopause and in the
     polar cusp.  To address this problem in situ observations both at high altitudes 
     and low altitudes, ground based measurements with radars, photometers
     magnetometers and riometers as well as simulations and theory were brought to
     bear.  Much was learned in the five years of the campaign.  The relative roles of
     reconnection and diffusion in forming the boundary layers was explored.  An
     appreciation that there was an exterior boundary layer outside the magnetopause
     current layer as well as inside was developed.  The role of pressure pulses and
     transient reconnection was examined as was the role of the foreshock in causing
     each.  The dispersion signatures in cusp plama was interpreted in terms of
     reconnection with the solar wind and various transient phenomena in the
     magnetosphere were identified with both pressure and reconnection transients.
     
          Most of these observations were obtained with instrumentation developed
     and operated before the GEM campaign began, although the ground-based
     program was active throughout the GEM period.  Thus it was fitting perhaps as
     finally new space data were beginning to appear from the Interball and POLAR
     missions that the GEM Boundary program transition from an NSF - managed
     program GEM to the IACG (Interagency Consultative Group).  Thus the final
     session of WG2 concentrated on first a review of the latest data from POLAR and
     Interball near the magnetopause and cusp, next on the theory of wave absorption
     on the cusp, and the use of ground-based pulsation data to identify the location
     of the boundary between open and closed field lines.  The session closed with a
     discussion of the future coordination activities that would take place under the
     auspices of the IACG.  Sergey Savin of the Interball Project and Hedi Kawano of
     GEOTAIL agreed to help coordinate future activities.  Nicola Fox volunteered to
     assist in this effort by maintaining a web page associated with those of the ISTP
     project.  The coordinators will work with the community to select intervals for
     joint analyses to maximize the return from the constrained resources of the various
     groups.  These special event periods will be both retrospective and prospective. 
     The former will be selected from intervals for which many data were obtained and
     in which the various spacecraft were well situated.  The latter intervals will be
     chosen to encourage the collection of a complete set of data when such upcoming
     consellations are identified.  The present GEM Boundary Layer Working Group
     2 Chairman wishes Sergey Savin and Hedi Kawano well in their efforts and
     thanks all the members of the GEM community who worked so hard to make the
     Boundary Layer campaign a success.
     
     
     C. T. Russell
     July 10, 1997

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