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			 **   THE GEM MESSENGER   **
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						     Volume 7, Number 29
						     July 19, 1997

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Snowmass Report 1997, GGCM Working Group-2
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From jbirn at lanl.gov Fri Jul 18 08:19:38 1997

The two-hour session of Working Group 2 focused on the role of the modular
approach within the GGCM. There appeared to be a consensus that the
development of modules plays an important part in the development of a GGCM,
whether considered as attachments to a "spine" or as parts of an
alternative approach that consists of distributed parallel modules.

Present and future modules can be divided into two groups:

(1) The spine itself or modules that can replace the spine for development
purposes or for more limited science studies, or serve as parts of the
parallel modular approach, such as:

Global MHD (as the present favorite spine)
Tail MHD
Global equilibrium models
Tail equilibrium models
Empirical magnetic field models
Parameterized field models

Anisotropic global MHD
Anisotropic tail MHD
Hall MHD (global or tail)

Global hybrid or particle models exist already but are limited to low
numbers of particles per cell and are not considered a viable alternative
yet.

(2) Modules to be considered as attachments to the spine or as parts of the
distributed parallel approach:

Magnetopause
Radiation belts (source, loss mechanisms etc.)
Ring currant
Plasmasphere
Auroral acceleration region
Ionosphere
Subionospheric region (sources, losses)
Collisionless dissipation (substorm onset or magnetopause context)
Turbulent transport
Anisotropy and isotropization
Energetic particle acceleration, injections (e.g., test particles)

Joe Borovsky presented a study of plasma sheet turbulence effects that can
be incorporated in MHD modules as an eddy-viscosity.
Adil Hassam investigated the role of subionospheric boundary conditions.
John Freeman presented the results of empirical fits to radiation
belt particle fluxes.
Jim Drake announced that a collaborative effort has been initiated to
compare the physics of collisionless dissipation in various models.

We would like to assess what modules exist and are being worked on. We are
also interested if you have experience in working with existing modules
(Janet Luhman gave a valuable presentation of her experience from the
user's perspective).  Useful information includes the necessary input and
output provided by a module, including possible feedback with a spine or
with other modules. An important part of the future development will be the
implementation of standard interfaces.

Please provide this information (even if it is just a title and a name).

Joachim Birn and Phil Pritchett

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Joachim Birn                                    phone:  (505) 667-9232
Space and Atmospheric Sciences (NIS-1)          fax:    (505) 665-3332
MS D466                                         e-mail: jbirn at lanl.gov
Los Alamos National Laboratory
Los Alamos, NM 87545
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