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			 **   THE GEM MESSENGER   **
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						     Volume 8, Number 11
						     April 22, 1998

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THE FIRST GEM SUBSTORM CHALLENGE
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From: Jimmy Raeder (jraeder at igpp.ucla.edu)

The concept of a "GEM Challenge" emerged about 2 years ago
in the GEM community.  Several periods of stable ionospheric
convection (during January 27/28, 1992) were identified and
the convection patterns determined with the AMIE method.
Modelers were challenged to model these events, reproduce
the convection patterns to the best ability of their models,
and to contribute to the understanding of these convection
patterns.  This challenge has been a great success as many
modelers with very different approaches responded.  Results
were presented at two Snowmass meetings, and a number of
papers are about to appear in a special JGR section dedicated
to this event.

The GEM Substorm Working Group 3 (Quantitative Tail and Substorm
Models) now proposes a new challenge.  This challenge is much
broader in scope and we hope to attract even more modelers who
are willing to have their models face the real world.  The event
in question is an isolated substorm that occurred on November 24,
1996, around 2230 UT, following an extended quiet period.  
Extensive data sets exist to provide model input, and for
comparison with model results.  Wind is located near
(73,-13,8) RE_GSE.  We have so far identified clear substorm
signatures in the following data sets:

Polar images
SuperDARN radars
ground magnetometers (onset right over Scandinavia)
LANL particle injections
GOES 8/9 magnetic field
Geotail (-21,-21,-3) RE_GSE, southward Bz turn

There are certainly numerous other data sets available that are
not included here and can be used for this study.  We will include
those also if they are provided to us.

We challenge the modelers to use their models to produce "predictions"
for this event and to compare their results with the appropriate
data.  We will schedule a special session at the 1998 GEM snowmass
meeting in which first results can be presented.  In that session
we also want to discuss if specific questions should be posed that
the models should address and the further timeline of this study.
We expect that this challenge should eventually lead to another
special JGR section.

Data and other relevant information regarding this challenge are
posted on a webpage (http://www-ggcm.igpp.ucla.edu/gemch1/index.html).
We invite investigators who have data that may be useful for this event
to participate in this study.

Looking forward to see you (and your results) at the 1998 GEM Snowmass
meeting!


Nelson Maynard and Jimmy Raeder

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