Solar-Terrestrial Coupling Processes (S-TCP) Workshop
Solar-Terrestrial Coupling Processes (S-TCP) Workshop
Friday, June 18, 01:00-05:30
Math-100
- CEDAR/GEM/SHINE plenary workshop on selected magnetic storm dates
- Solar-Terrestrial Coupling Processes (S-TCP) Workshop
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@engin.umich.edu), David Webb (webb@plh.af.mil) or Michael
Buonsanto (mjb@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
.
- 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?
Back to CEDAR Agenda 1999