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			 **   THE GEM MESSENGER   **
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                                                        Volume 19, Number 20
                                                               June 17, 2009
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Second Call for Contributions: GEM Focus Group "GGCM Methods and Modules"
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From: John Dorelli <john.dorelli at nasa.gov>

This is the second announcement for the GGCM Methods and Modules Focus Group.  
Thanks to those who responded to the first announcement.  We would like to 
invite participants to two sessions to be held at the summer GEM workshop in 
Snowmass June 21-26.  Both sessions will be held Wednesday, June 24:

Session 1 (10:30 am):  The physics of collisionless magnetic reconnection.

In this session, we would like to continue where we left off last year, 
addressing the following issues:

1.  What is the role of secondary magnetic islands?  Are they an irrelevant 
by-product, or do they play an essential role in determining the aspect 
ratio of the dissipation region?

2.  What limits the aspect ratio of the electron dissipation region?

3.  How does the reconnection rate scale with dissipation scale parameters 
(e.g., resistivity or electron mass) in simulations (electron MHD, Hall MHD, 
hybrid, fully kinetic)?

However, those who wish to address other aspects (from both observational 
and theoretical perspectives) of collisionless reconnection (in particular, 
the electron diffusion region) are encouraged to participate.

Session 2 (1:30 pm):  Global modeling of magnetic reconnection in the 
magnetosphere.

Topics for this session include:

1.  How does the physics of reconnection depend on the ad hoc resistivity 
model used in global MHD codes?  In particular, how does reconnection scale 
with resistivity in the high Lundquist number limit? What is the effect of 
numerical resistivity? Can we reproduce Petschek reconnection by localizing 
the plasma resistivity? What is the effect of current dependent resistivity?

2.  How does dayside magnetopause reconnection work in global MHD codes? Is 
reconnection locally controlled or externally driven?  Does the Cassak-Shay 
formula apply to the dayside magnetopause?

3.  What is the status of global Hall MHD modeling?  What are the most 
robust numerical approaches?  What are the new results coming from the 
latest generation of global Hall MHD magnetosphere codes?

4.  What is the status of other non-MHD approaches to global magnetosphere 
modeling (e.g., global hybrid codes)?  Are there any new ideas on the 
horizon?

If you are interested in participating in either of these sessions, please 
email one of the focus group co-chairs:  john.dorelli at nasa.gov, 
brian.sullivan at unh.edu or shay at udel.edu.
	    

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