Paper#: 49
Poster #: 29
Session Name: Poster Session 1
Room: East Ballroom
Day: Tuesday
Time: 10:10 a.m.-Noon
Abstract Title: A Substorm Event Study with Observations by Cluster And Ground-Based Instruments.
PresentSurname: E. Boralv
All Authors: E. Boralv, M. Andre, H. Opgenoorth, M. Dunlop, J.-M. Bosqued, A. Fazakerley
Abstract : We will present a substorm event study using Cluster and ground-based instrumentation. On September 19, 2001, ground-based magnetograms show a double substorm onset over Scandinavia in the pre-midnight sector. Within an hour two separate substorm intensifications are apparent in the magnetograms. For the onset and the first intensification, corresponding plasma sheet thinnings and thickenings are visible at Cluster, located in the plasma sheet at a downtail distance of about 18 Re. The Cluster observations of the two intensifications differ, the first one giving rise to a temporary re-entry into the plasma sheet, suggesting a dipolarization effect, the second and weaker one not producing any noticeable signatures at this downtail distance. In the late recovery phase of the substorm the thickening of the plasma sheet to pre-substorm values can be seen at Cluster. A detail of interest is that the ground signatures of the substorm precede the Cluster particle drop-outs. Our aim in this study is to use the four Cluster satellites in combination with ground-based instruments in order to provide us with new insights on simultaneous observations in different magnetospheric regions and subsequently the large-scale substorm process.