The ISTP Observatory has established a framework for the detection of solar events, monitoring their evolution through the interplanetary medium and evaluating of their impact on geospace. The January 6-11, 1997 event is an example of the "Cradle to Gra
ve" observation and analysis capability of GGS and will serve as a prototype to the more frequent and active events anticipated at solar maximum. Events of this type also illustrate how an integrated system is necessary to address global Sun-Earth connect
ions.
The birth and early evolution of a CME were initially detected by the SOHO LASCO and WIND/WAVES instruments on January 6 and predictions were made that it would sweep over the magnetosphere four days later. In the days following, the WIND spacecraft tra
cked the resultant interplanetary structure approaching the Earth using radio emissions originating from the shock front. Early on January 10, WIND instruments observed the classical signature of a magnetic cloud, whose trailing edge contained an enormous
density enhancement.
The WIND plasma and energetic particle measurements showed the first evidence that cold, chromospheric temperature plasma, probably solar filament material, had been ejected in a cloud. The WIND measurements showed that the composition of this material was highly unusual, with enhanced 3He+ and other anomalies. These measurements may be used to study the fractionation process in the solar atmosphere, as well as the coronal heating process, thus providing a direct connection back to the Sun.
When the cloud hit the magnetosphere the POLAR auroral imagers saw the effects of a sudden commencement sweep across the polar cap. A moderate magnetic storm ensued, whose global ring current was observed by means of Energetic Neutral Atom Imaging from POLAR to grow and decay in remarkable coincidence with the magnetic effects of the ring current as indicated by the Dst index relationship. POLAR energetic particle instruments and similar instruments on geostationary satellites monitored a large buildup of trapped MeV electrons. The ground-based SuperDARN radar network observed an initial enhancement in high-latitude convection when the southward-directed interplanetary magnetic field in the shock preceding the magnetic cloud, impacted the magnetosphere. In association with the main cloud arrival, strong global ionospheric currents were excited and observed by CANOPUS and other magnetometer networks. The trailing edge density enhancement compressed the magnetosphere, moving the dayside magnetopause earth ward of the geosynchronous orbit and the flanks several Earth radii inside the average boundary location. Coincidentally with the buildup of energetic electrons in the magnetosphere, the Telstar 401 communications satellite experienced a massive power sys tem failure. Remarkably all this activity occurred during solar minimum! Within a few days of the event, global simulations were run based on the temporal properties of the solar wind as measured by WIND, that illustrated spectacular dynamic responses of the magnetosphere. For the first time, a movie of the global magnetosph eric response to a CME and its related transients was produced in a matter of days using a self-consistent global magnetospheric simulation code with real solar wind input. |
![]() Figure 2-3. POLAR VIS observations of the dynamic auroral oval. Figure 2-6. UMD Global Simulation of Magnetospheric Response to Magnetic Cloud of Jan 10-11, 1997. |