HR: 14:05h
AN: SM23C-02    [Abstracts]
TI: Evolution of a staircase ion signature observed by Cluster in the polar cusp
AU: * Escoubet, C P
EM: philippe.escoubet@esa.int
AF: ESA/ESTEC, Keplerlaan 1, Noordwijk, 2200 AG Netherlands
AU: Bosqued, J M
EM: Jean-Michel.Bosqued@cesr.fr
AF: CESR, 9 Avenue du Colonel Roche, Toulouse, 31028 France
AU: Berchem, J
EM: jberchem@igpp.ucla.edu
AF: UCLA/IGPP, 405 Hilgard Avenue, Los Angeles, CA 90095-1567 United States
AU: Taylor, M G
EM: mtaylor@rssd.esa.int
AF: ESA/ESTEC, Keplerlaan 1, Noordwijk, 2200 AG Netherlands
AU: Pitout, F
EM: fpitout@mpe.mpg.de
AF: MPE, Giessenbachstrasse, Garching, 85748 Germany
AU: Laakso, H
EM: harri.laakso@esa.int
AF: ESA/ESTEC, Keplerlaan 1, Noordwijk, 2200 AG Netherlands
AU: Masson, A
EM: Arnaud.Masson@esa.int
AF: ESA/ESTEC, Keplerlaan 1, Noordwijk, 2200 AG Netherlands
AU: Dunlop, M
EM: m.dunlop@rl.ac.uk
AF: RAL, Chilton, Didcot, OX11 0QX United Kingdom
AU: Reme, H
EM: Henri.Reme@cesr.fr
AF: CESR, 9 Avenue du Colonel Roche, Toulouse, 31028 France
AU: Dandouras, I
EM: iannis.dandouras@cesr.fr
AF: CESR, 9 Avenue du Colonel Roche, Toulouse, 31028 France
AU: Fazakerley, A
EM: anf@mssl.ucl.ac.uk
AF: MSSL, Univ. College London, Holmbury St. Mary, RH5 6NT United Kingdom
AB: We use the Cluster string of pearl configuration in the mid-altitude polar cusp to investigate temporal variations of the polar cusp. On 7 Aug. 2004, Cluster 4 was moving poleward through the Northern cusp, followed by Cluster 1 about 3 min later, Cluster 2 about 9 min later and finally Cluster 3 about 18 min later. The ACE spacecraft detected a Southward IMF turning before the cusp crossings and Bz stayed negative throughout. Cluster 4 observed a staircase ion dispersion with 2 steps, a high energy one around 1 keV at low latitude and a low energy one at higher latitude. C1 around 3 min later did not observe the high energy step anymore but a dispersion with a low energy cut-off more or less continuous through the cusp. About 18 min later, C3 observed a new dispersion on the equatorward side of the cusp detached from the main cusp precipitation. The observations will be compared with the predictions from a three-dimensional magnetohydrodynamic (MHD) simulation. This event will then be discussed in term of temporal evolution of newly reconnected field lines on the equatorward side of the cusp under IMF-Bz negative.
DE: 2463 Plasma convection (2760)
DE: 2706 Cusp
DE: 2776 Polar cap phenomena
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005