HR: 13:40h
AN: SM33C-01    [Abstracts]
TI: Speed of Compression of Magnetosphere by CME Clouds
AU: Nanan, B
EM: b.nanan@sheffield.ac.uk
AF: University of Sheffield, ACSE, Mappin Street, Sheffield, S1 3JD, United Kingdom
AU: Alleyne, H
EM: h.alleyne@sheffield.ac.uk
AF: University of Sheffield, ACSE, Mappin Street, Sheffield, S1 3JD, United Kingdom
AU: * Walker, S
EM: s.walker@sheffield.ac.uk
AF: University of Sheffield, ACSE, Mappin Street, Sheffield, S1 3JD, United Kingdom
AU: Lucek, E
EM: e.lucek@imperial.ac.uk
AF: Imperial College, London, Blackett Laboratory, London, SW7 2BZ, United Kingdom
AU: Reme, H
EM: Henri.Reme@cesr.fr
AF: CESR, CESR Cedex-4, Toulouse, F-31028, France
AU: Fazakerley, A
EM: anf@mssl.ucl.ac.uk
AF: University College London, MSSL, London, SW 7, United Kingdom
AB: The multi-point Cluster observations provide the opportunity to study the speed of compression of the magnetosphere at the impact of extreme solar events such as CMEs. The four-point Cluster FGM (high resolution), CIS and PEACE data during the passage of 17 CME clouds during 2001-2005, together with models of magnetosphere and magnetopause, are used to obtain the speed of compression of the dayside magnetosphere. The study shows that the speed of compression (within three seconds of impact) increases with the dynamic pressure of the CMEs, and that this speed exceeds the speed of the CMEs in some (five) cases (suggesting impulsive response) when the dynamic pressure of the CMEs exceed about 20 nPa. The magnetosphere is also found to undergo damped oscillations for about two minutes after the impact of some extreme CMEs (24 October 2003 and 29 October 2003) until the magnetic pressure outside and inside the magnetopause balances. The speed of compression is also found to increase with the negative IMF Bz of the CME suggesting that part of the compression is due to CME pressure and another part is due to magnetic reconnection. The plasma data (PEACE and CIS), though of low resolution (4 seconds), are being analysed to check if the magnetic field and plasma move together or do they undergo differential motion (important for magnetic field-plasma interactions at short time scales).
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
DE: 2720 Energetic particles: trapped
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting