HR: 1330h
AN: SM12A-1194    [PDF]
TI: Magnetospheric Cusp Observed by Cluster on 18 April 2002
AU: * Alleyne, H
EM: h.alleyne@sheffield.ac.uk
AF: Control and Systems Eng., University of Sheffield, Sheffield, S1 3JD United Kingdom
AU: Balan, N
AF: Control and Systems Eng., University of Sheffield, Sheffield, S1 3JD United Kingdom
AU: Walker, S
AF: Control and Systems Eng., University of Sheffield, Sheffield, S1 3JD United Kingdom
AU: Decreau, P
AF: LPCE/CNRS, Universited d'Orleans, France, FR France
AU: Andre, M
AF: I.R.F.U, Uppsale, Sweden, SW Sweden
AU: Balogh, A
AF: Blackett Laboratory College, Imperial College, London, LO United Kingdom
AU: Fazakerley, A
AF: Space and Climate Physics, University College, London, LO United Kingdom
AU: Reme, H
AF: CESR, Toulouse, Sweden, SW Sweden
AU: Cornilleau, N
AF: CETP/CNRS and VSQP University, Uelizy, France, FR France
AU: Gurnett, D
AF: University of Iowa, Iowa, USA, Iowa, IO United States
AB: Results are presented from a study of the northern magnetospheric cusp crossed by the 4 Cluster satellites during 16:25-17:55 UT on 18 April 2002 when the solar wind dynamic pressure was rather low and IMF Bz was suitable (southward) for reconnection at subsolar magnetopause. The satellite orbit and data from the FGM, CIS, PEACE, STAFF and WHISPER instruments reveal that the satellites have crossed through the edge of a structured exterior cusp. Three distinct anti-sunward ion flow events of duration about 1.5, 17.5 and 19.0 minutes, with bulk flow roughly parallel to the magnetopause surface, are detected in the cusp region. The ion density in the events measured by one of the satellites (C3) is up to 10 times less than that measured by other satellites (C1 and C4, no data from C2), which seems to arise from the low northward-westward flow encountered by C3 compared to C1 and C4. The magnetic field fluctuations in By ($\approx$ 50 nT) associated with the anti-sunward ion flow events are nearly twice as strong as those in Bx and Bz, suggesting strong field-aligned currents. The sharp inward/outward walls in all directions of the anti-sunward flow events are detected with expected/reversed time sequence by the 4 satellites, with time delays of up to 10 sec./4 sec. That suggests reversed and accelerated plasma flows in all directions inside the events (faster acceleration closer to the walls) compared to the flows outside the events.
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2730 Magnetosphere--inner
DE: 2731 Magnetosphere--outer
DE: 2732 Magnetosphere interactions with satellites and rings
DE: 2736 Magnetosphere/ionosphere interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting