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?