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			 **   THE GEM MESSENGER   **
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						     Volume 16, Number 5
						     April 7, 2006

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Solicitation of contribution to the "Plasma Acceleration and
Transport in the Magnetotail" (PATM) Working Group of the 
GEM Global Interactions campaign
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From: Benoit Lavraud, Terry Onsager, Antonius Otto, and Simon Wing
      PATM coordinators

With this letter, we would like to invite potential contributors to the 
PATM working group of the GEM-GI campaign to contact the conveners about 
their current efforts in the topics related to this working group. 
Although the sessions at the upcoming meeting will be held in a 
workshop-style, time for a few slides will be allotted for contributors 
to present results, as well as ideas about the campaign development. Two 
primary topics for discussion at GEM are listed below. We welcome 
feedback and suggestions prior to the workshop to further focus these 
working group activities. 

A general outline of the major working group topics of interests 
throughout this campaign has been devised and is available at 
http://gem.rice.edu/~gem/gem2006/PATM_GEM_outline.pdf  
Comments on this draft from the community are welcome. From all the 
topics included in this more complete outline, two primary objectives 
have been selected. These primary topics are associated with challenges 
to the modeling community and the data required to test the models. They 
are described below and will be specifically discussed and addressed 
during our allotted splinter sessions in the upcoming GEM meeting (held 
again in Snowmass, 25 - 30 June, 2006).

We thus invite potential contributors to the PATM working group to focus 
their efforts (observation and modeling) on the following topics and 
challenges; the focus of these topics may be discussed and refined 
during the workshop for future years. We invite contributors to contact 
the conveners indicating their interest in participating, as well as 
suggestions for time intervals and subtopics to further focus the 
discussions:

1) What are the preferred mechanisms and their relative efficiencies for 
solar wind plasma entry (reconnection, Kelvin-Helmholtz, diffusion)?

Challenge: Estimate the relative efficiencies of the different plasma 
entry processes. What constitutes observational evidence for the 
different plasma entry mechanisms and how can this be used to specify 
and quantify the efficiency of the competing mechanisms depending on 
IMF orientation? Can global MHD models be modified to include 
Kelvin-Helmholtz at the flanks (grid resolution)? What other techniques 
can be used to evaluate the efficiency of these processes (in terms of 
plasma transfer to the plasma sheet), e.g., using local simulations and 
observations?

2) What are the transport paths and associated time-scales from the 
source locations on the magnetopause and in the ionosphere to locations 
in the plasma sheet?

Challenge: What are the dominant transport mechanisms (coherent plasma 
flow, turbulent flow, particle drifts, etc.) within the boundary layers 
and plasma sheet and in how far can observations (convection, dawn-dusk 
asymmetries, etc.) shed light on the physics of this transport? Based on 
known changes in the solar wind input and ionospheric outflows, can the 
observed changes in plasma sheet properties (including composition) be 
reproduced by models (MHD, particle tracing, and others)? 

Benoit Lavraud, Terry Onsager, Antonius Otto, and Simon Wing
PATM coordinators

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