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			 **   THE GEM MESSENGER   **
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						     Volume 9, Number 11
						     April 27, 1999

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Report of 1998 GEM Snowmass Workshop: Substorm Observations Working Group
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From: Mark Moldwin (moldwin at galileo.pss.fit.edu)

Co-Chairs: Shin Ohtani - JHU/APL and Mark Moldwin - Florida Institute of
Technology

GEM 98 was the first workshop in which the new working group named
"Substorm Observations" held sessions. The goal of the working group was to
identify all the substorm onset signatures - model independently - and to
attempt to organize them in terms of their temporal relationship. The
working group had two plenary tutorials: John Olson from the University of
Alaska - Fairbanks gave a tutorial on Pi 2 Observations while Mark Moldwin
from Florida Institute of Technology gave a tutorial on Substorm onset
signatures.

Within the working group sessions tutorials were given by Howard Singer on
the response and role of the Inner Magnetosphere during substorms and
Ching Meng on the temporal relationship of substorm onset signatures as
seen in the ionosphere and plasma sheet. In addition, dozens of other
participants presented workshop summaries of substorm onset signatures that
ranged from the timing relationship between various signatures to the first
ENA images of substorm injections.

The main consensus "action item" that developed out of the workshop was
that a reference time for ordering substorm phenomenology and signatures is
needed to be able to compare results from a variety of instruments,
platforms, locations, and definitions. Mid-latitude, nightside Pi 2
pulsations were suggested to be this substorm onset T(reference).
Semantically T(reference) was preferred to T0 in that it does not imply the
initial cause of substorm onset but rather a fiducial which can be used to
order different observations. Studies that look at the relative timing and
consistency of ordering of different substorm signatures with respect to
mid-latitude Pi 2s were suggested. A special  "Substorm
Timing" session was held at the Fall 98 AGU as an outgrowth of this
working group.

GEM 99 will continue this working groups objectives of identifying and
ordering substorm onset signatures. Working group sessions on substorm
timing, ground-based magnetometer signatures, and substorm signatures in
the plasma sheet will be the focus of this years workshop.

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