HR: 08:15h
AN: SM51A-02    [PDF]
TI: Multi-spacecraft observations of the structure and motion of field-aligned cusp currents under strong IMF B$_X$ and B$_Y$ conditions
AU: * Stubbs, T J
EM: tstubbs@lepvax.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Bldg 21 Rm C218, Mail code 690.4, Greenbelt, MD 20771 United States
AU: Dunlop, M W
EM: m.dunlop@rl.ac.uk
AF: Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX United Kingdom
AU: Bosqued, J
EM: bosqued@cesr.fr
AF: CESR/CNRS, 9, Avenue du Colonel Roche BP 4346, Cedex 4, Toulouse, 31028 France
AU: Cargill, P J
EM: p.cargill@imperial.ac.uk
AF: Imperial College, Space \& Atmospheric Physics, The Blackett Laboratory, London, SW7 2BW United Kingdom
AU: Taylor, M G
EM: mggtt@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, Mail stop D466, Los Alamos, NM 87545 United States
AU: Fazakerley, A
EM: anf@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, RH5 6NT United Kingdom
AU: Owen, C J
EM: cjo@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, RH5 6NT United Kingdom
AB: Field-aligned cusp currents are the mechanism by which momentum and energy are transferred from the solar wind to the ionosphere during reconnection. On 25 August 2001, the Cluster spacecraft flew through the northern polar cusp and observed large-scale deflections of the magnetospheric field (FGM) and field-aligned electrons (PEACE) indicative of strong field-aligned currents, together with dispersed cusp-ion signatures (CIS) that are associated with pulsed reconnection. This occurred during periods of weak southward IMF accompanied by strong IMF B$_Y$ $>$ 0 and B$_X$ $<$ 0. Similar observations of reconnection pulses have been made in the past and linked to poleward-moving auroral forms (PMAFs), which appear to occur on open field lines. Successive reconnection pulses during these type of events can contribute almost all of the voltage across the magnetosphere. However, these single spacecraft observations in the mid-altitude cusp were constrained by assumptions about the cusp structure and the relative spacecraft and boundary motions - this could easily lead to large errors in the analysis. With multi-spacecraft observations we can better constrain these parameters and make better estimates of the field-aligned currents. The formation of the Cluster spacecraft during this interval also allows us to study in-situ the evolution of the cusp on timescales of minutes to tens of minutes.
DE: 2708 Current systems (2409)
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting