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			 **   THE GEM MESSENGER   **
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						     Volume 9, Number 14
						     May 17, 1999


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First Announcement for the Joint CEDAR-GEM-SHINE Magnetic Storms Campaign
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From: Janet Kozyra (jukozyra at srvr5.engin.umich.edu)

The campaign begins with:

Solar-Terrestrial Coupling Processes (S-TCP) Workshop: Friday, June 18, in
     Boulder, Colorado.  Includes plenary speakers, panel and afternoon
workshop
     to explore the three selected events (described below) and develop a
     campaign strategy.  See
     http://www.hao.ucar.edu/public/research/tiso/cedar/99/conf99.html for
     details and workshop agenda.

Call for Participation:  We are soliciting comments on additional science
     topics/issues that can be addressed, information on available data sets,
     and presentations for the June 18 workshop dealing with science topics
     appropriate to this campaign.

What to do:
     Please send comments and suggestions for the workshop to either:  Janet
     Kozyra (kozyra at engin.umich.edu), David Webb (webb at plh.af.mil) or Michael
     Buonsanto (mjb at haystack.mit.edu).  Let us know if you plan to attend the
     workshop and have information to present on these events or on science
     issues addressable using observations from these events.

     To facilitate collaborations and aid in the development of a
     campaign strategy focused around broad science issues, we would like to
     post summary data (along with contact information) for these storm events
     at http://leadbelly.lanl.gov/GEM_Storms/GEMstorms.html.  If you
     have summary plots for these intervals, please email Geoff Reeves
     <reeves at lanl.gov>.

     More Information about these events can be found at:
     http://aoss.engin.umich.edu/intl_space_weather/sramp/SHINE_GEM_CEDAR.html
     and http://leadbelly.lanl.gov/GEM_Storms/GEMstorms.html


Campaign Focus: The Geoeffectiveness of Coronal Mass Ejections

Strategy:   To compare and contrast a small number of well-observed magnetic
     cloud events to isolate and understand some of the most pressing science
     issues associated with the generation of CMEs, their association with
     interplanetary magnetic clouds, the interaction of magnetic clouds
with the
     interplanetary medium, and the response of the terrestrial environment

Event Selection Criteria:
     * A halo CME observed by the SOHO LASCO experiment that appeared to be
       aimed Earthward
     * A magnetic flux rope signature detected by WIND and/or ACE 3-5 days
later
     * A major (Dst<-100 nT) geomagnetic storm triggered
     * A reasonably complete data set for the event.  To meet this criteria,
       events were selected:   (1) with as complete as possible information on
       the solar source regions, (2) with uninterrupted ACE and/or WIND
       coverage,  (3) after the launch of the POLAR spacecraft to provide as
       complete as possible magnetospheric coverage and (4) during incoherent
       scatter world days, if possible, maximizing crucial information on the
       ionosphere/atmosphere response.

Selected Events
     * 15-18 May 1997
     * 24 Sep - 01 Oct  1998
         (also an ISTP event study, ISR World Days were 21-25 Sep)
     * 18-31 October 1998
         (ISR World Days were 19-21 Oct)

Description of the Events and Suggested Science Topics/Issues:

     * Differences in Solar Sources:
          * Sep 98:  CME  associated with strong flare activity
          * Oct 98:  CME associated with an erupting filament
          * May 97:  CME associated with both a flare with a coronal wave
and an
            erupting filament

     * Solar Wind Features:
          * Magnetic Cloud Characteristics:
            All were magnetic clouds with flux rope signatures.  Inclination of
            the axis with respect to the ecliptic plane varied between the
            events and may be an important factor in determining the
            geoeffectiveness of these structures. The flux rope orientation
can
            often be related to that of the solar source region, especially an
            erupting filament.
               * May 97:  Simple S-N magnetic flux rope with axis in the
                           ecliptic plane embedded in a relatively undisturbed
                           solar wind background.  Successfully fit with a flux
                           rope model by the WIND MFI team.  Can this be
used as
                           a baseline against which to interpret the more
                           complex Sept 98 and Oct 98 events?
               * Sep 98 and Oct 98:  Axes of flux rope highly inclined to the
                           ecliptic plane for both events.  Sep 98 event
                           successfully fit to a S-N magnetic flux rope
model by
                           the WIND MFI team.  Southward Bz in the magnetic
                           clouds for these events was comparable in both
                           magnitude and duration.  However the Dst min for Sep
                           98 was ~-233 nT and that for the Oct 98 event was
                           ~-139 nT.   The difference in the geoeffectiveness
                           may be partially related to the large
differences in
                           solar wind velocity for the two clouds.

          * Shock Structures:
            Fast CMEs with shocks often bring geoeffective southward magnetic
            fields due to the turbulent region behind the shock, and
compression
            and/or draping of the ambient field. Such shocks can also
accelerate
            particles to high energies that can affect geospace.
               * May 97: traveled at ~550 km/s and was preceded by a
                          significant shock.  This event produced moderately
                          energetic protons.
               * Sep 98: traveled at 800 km/s and was preceded by a
                          significant shock
               * Oct 98: traveled at ~400 km/s and was preceded by only a weak
                          shock

    * Magnetosphere-Ionosphere Responses:
           * May 97 Event:
               * Minimum Dst ~-115 nT.
               * In-situ acceleration of radiation belt electrons on time
scales
                 of tens of minutes at L~3-4
               * High-density plasma sheet
               * Activity abruptly terminated as the Bz in the magnetic cloud
                 rotated northward.  Initial recovery of the Dst was very
rapid,
                 giving the storm a clear two-phase decay.
           * September 98 Event:
               * A sudden impulse (SI) was observed in association with the
                 interplanetary shock ahead of the magnetic cloud along with a
                 significant compression of the dayside magnetopause.
                 Magnetosheath observed at geosynchronous orbit by LANL
                 spacecraft during two time intervals.
               * During the passage of the SI, enhanced ionospheric ion
                 outflows, intense field-aligned currents and brightening of
                 the dayside aurora were seen.
               * The magnetic cloud with southward IMF followed and, for a full
                 day, caused a magnetic storm with minimum Dst ~-233 nT.  The
                 ring current had a clear two-phase decay.
               * The cloud may have occurred at the start of a recurrent high-
                 speed solar wind stream.
           * October 98 Event:
               * A magnetic storm with minimum Dst of -139 nT occurred but with
                 an extremely long recovery phase.
               * Highest solar wind density and dynamic pressure of the three
                 events. Magnetosheath encounter by the LANL geosynchronous
                 spacecraft near 4 UT on 19 Oct 98.
               * Solar wind speeds following the IMC increased from 400 km/s in
                 the magnetic cloud to 600 km/s behind the cloud, possibly
in a
                 high-speed stream.  The IMF Bz was small following the
magnetic
                 cloud and fluctuated from north to south repeatedly preventing
                 the Dst from recovering to pre-storm values.

     * Campaign Science Issues
           Given the characteristics of the solar wind structures, location of
           satellites and known M-I responses, potential science topics for the
           magnetic storms campaign include:
               * How elements in interplanetary magnetic clouds (IMCs)
relate to
                 their solar source regions?  Can these elements be predicted
                 from knowledge of the solar source?
               * Are such associated solar signatures of CMEs as flares,
                 filament eruptions and coronal waves related to the
                 geoeffectiveness of IMCs and, if so, how?
               * What features impact the geoeffectiveness of interplanetary
                 magnetic clouds (i.e., role of high solar wind speeds,
                 inclination to the ecliptic plane, etc.)?  and associated
                 structures (i.e., shocks, and high-density solar wind, etc.)?
               * Storm-substorm relationships
               * Plasma sheet dynamics and relationship to ring current
                 formation
               * Role of sudden impulses and solar energetic particles in
                 radiation belt enhancements
               * Ionospheric consequences of reconnection
               * Ion outflow (or the ionospheric source for magnetospheric
                 plasma), relative importance of the auroral zone and cleft
ion
                 fountain.
               * Energy dissipation, feedback and coupling mechanisms
(e.g., how
                 are magnetospheric electric fields modified by the ionosphere,
                 thermosphere?)
               * What can multipoint timing studies tell us about time scales
                 for the interaction between the solar wind, magnetosphere,
                 ionosphere?
               * What are the magnetospheric effects of the small spatial scale
                 structures of the high-latitude ionospheric conductance?
               * Others?



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