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Reports of the 6 December GEM WG Meetings in San Francisco
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		      WG5:    GGCM WORKING GROUP
		 Co-chairs: Joel Fedder and George Siscoe

   The inaugural meeting of the GGCM Working Group (GGCM-WG) was held on
December 6, 1992, together with the meetings of the other GEM Working 
Groups, which were held in conjunction with the Fall AGU Meeting in San
Francisco. The meeting had three objectives: 1. Review the generic types 
of GGCM's as a first step toward optimizing GEM's role in their development;
2. Identify GEM Milestones--relatively short duration, high-impact projects
that can be implemented through the GEM program and that contribute to the 
overarching goal of the program; and 3. Discuss GGCM-WG organizational 
matters.
   There were three invited talks on GGCM types. Dick Wolf reviewed the
Rice Convection Model (RCM) as an example of a modular GGCM. Joel Fedder
pointed out the strengths of global MHD models. Dan Swift described a 
global hybrid code--kinetic ions/fluid electrons--being developed to run
on MPP architecture computers. The detailed reports on the three
presentations will be published on The GEMstone soon.
   The discussion on GEM Milestones project brought to light the 
possibility of uniting the magnetic field of a global MHD code with the
particle drift code of the RCM. This would address major shortcomings
of each approach: the RCM's magnetic field is not self-consistently
determined, and an MHD model has no gradient and curvature drift features
and processes. Dick Wolf and Joel Fedder agreed to look into how such
a combined model might be implemented. Another GEM-MP had already been 
defined at the Snowmass Workshop. Stahara and Spreiter are in contact 
with Joachim Birn to look at the possibility adding Birn's MHD plasma
sheet model with Spreiter and Stahara's vacuum Chapman-Ferraro model
with tail.
   The meeting was highly informative; it generated many useful 
discussions; and it left the GGCM-WG coordinators with much to do to 
assimilate the material and prepare for the next Snowmass Workshop.