*************************** ** THE GEM MESSENGER ** *************************** Volume 4, Number 5 February 17, 1994 -------------------------------------------------------- Report on the Dec. 5, 1993 GEM Mini-Workshops -- Part II -------------------------------------------------------- Working Group 5: GGCM George Siscoe The pre-AGU WG 5 session began with a brief report on the 2-day October meeting of the working group held at Boston College. The WG 5 report on the Snowmass Workshop in an earlier GEM Messenger described the substance of that meeting. It clarified the WG's near-term goal and delegated tasks to reach it. Its near-term goal (i.e., 2 to 3 year time scale) is to construct a prototype of a modularized GGCM. 'Prototype' means a GGCM that has scientific applications (e.g., model testing) and commercial applications (e.g., predictions). The WG divided the GGCM into three subunits: a core unit, a magnetopause-boundary-layer unit, and a substorm-and-tail unit. The core unit comprises a magnetosheath module, a polar-cap-electric-field-mapping module, an inner-magnetosphere- convection module, and an ionosphere-specification module. Highly serviceable versions of these modules already exist. Combining them is a feasible "two-year" task producing a valuable prediction-quality GGCM, satisfying the requirement of achieving at least advanced development leading to commercial applications. The magnetopause-boundary-layer and substorm-and-tail units are intended to test boundary layer and substorm models. The idea is to adapt existing alternative models for integration into the core unit. Runs of the thus-augmented core unit can be compared with observations. This tests the models more thoroughly than possible for models in isolation, satisfying the requirement of achieving scientific applications. Carrying out the Boston College agenda is explicitly a matter of solving interface problems. The task of marshaling community effort to develop interfaceable codes for the various models and for defining interface variables and standards was assigned to Dick Wolf (core unit), Bill Lotko (boundary unit), and Michael Hesse (Goddard Space Flight Center) (substorm unit). The subgroup leaders were invited to describe their plans at the December 5 meeting. Basically, the elements of the subunits were described and some progress toward defining how to treat the interface problems was reported. Michael Hesse has received positive responses from several of the key substorm modelers for the idea of developing versions of their models that can be interfaced with the core unit. The idea that the boundary unit and substorm unit might be treated as subroutines of the core program appeared to be a promising approach. The WG heard invited presentations from David Stern and Kolya Tsyganenko on the modeling program at Goddard. The Goddard program emphasizes magnetic field models. It uses a variety of theoretical and empirical approaches. This gives it flexibility in being able to tailor models to particular applications, such as Tom Sotirelis demonstrated at the Snowmass Workshop. After many years of dedicated effort, it has reached a state of high maturity and sophistication. It has generated a veritable library of field models, many of which, or derivatives of them, are used by different groups in the world. Stern demonstrated the power of some of the latest products. They are now able to simulate many of the features of the regions 1 and 2 currents. Tsyganenko described the improvements he is incorporating in a new version of his semi-empirical model, which has achieved the unofficial status of the standard field model for the discipline. It was agreed that the Goddard and the GEM modeling efforts are complementary, and that more interactions between the programs should take place. Robert Winglee requested time to describe the program he is conducting at the University of Washington on global magnetospheric modeling using full particle simulations. Global modeling is traditionally the prerogative of MHD, but Winglee demonstrated that full particle simulations can reproduce global features and can reveal some surprises. The demonstration made clear that full particle global simulation is an approach to magnetospheric modeling whose development can yield valuable, perhaps unique, additions to our knowledge of magnetospheric physics and behavior. Returning to the near-term goal defined at the Boston College workshop, the WG listed its set of GEM Milestones: 1. Module Specification (Magnetosheath Module, Electric Field Mapping Module, Augmented RCM Module, and AMIE; These are stand-alone modules that integrate into the core program) 2. Interface Standards Defined 3. Interfacing Modules of the Core Unit 4. Interfacing Boundary Layer Modules to the Core Unit 5. Interfacing Substorm Modules to the Core Unit. Each of these items is important enough to label as a GEM Milestone with full press coverage in Eos and in some cases in Science. Items that still need to be defined were also listed: 1. Integration of WG Efforts 2. Communication between WG 5 Subgroups and Pacing of their Efforts 3. Marketing and Public Relations for the GEM Program These items need to be addressed at the next Snowmass Workshop. As agenda items for the next Snowmass Workshop, the WG listed the following: 1. Lecture Topic: Space Weather: The Big Picture 2: Reports from Subworking Group Leaders 3. Reports on Other Projects 4. Round Table Discussion: Relation of Space Physics to a National Space Weather Service (NSWS). Needs of a NSWS in terms of Model Outputs 5. 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