HR: 0800h
AN: SM41B-1179    [Abstracts]
TI: Electric Field Signatures at Density Gradients
AU: * Johansson, T
EM: tommy.johansson@alfvenlab.kth.se
AF: Division of Plasma Physics, Alfv‚n Laboratory, Royal Institute of Technology, Teknikringen 31, Stockholm, 10044 Sweden
AU: Marklund, G
EM: goran.marklund@alfvenlab.kth.se
AF: Division of Plasma Physics, Alfv‚n Laboratory, Royal Institute of Technology, Teknikringen 31, Stockholm, 10044 Sweden
AU: Karlsson, T
EM: tomas.karlsson@alfvenlab.kth.se
AF: Division of Plasma Physics, Alfv‚n Laboratory, Royal Institute of Technology, Teknikringen 31, Stockholm, 10044 Sweden
AU: Lileo, S
EM: sonia.lileo@alfvenlab.kth.se
AF: Division of Plasma Physics, Alfv‚n Laboratory, Royal Institute of Technology, Teknikringen 31, Stockholm, 10044 Sweden
AU: Lindqvist, P
EM: per-arne.lindqvist@alfvenlab.kth.se
AF: Division of Plasma Physics, Alfv‚n Laboratory, Royal Institute of Technology, Teknikringen 31, Stockholm, 10044 Sweden
AU: Fazakerley, A
EM: anf@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College, 138 London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK, RH5 6NT, Surrey United Kingdom
AU: Marchaudon, A
EM: am@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College, 138 London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK, RH5 6NT, Surrey United Kingdom
AB: How the signature of auroral electric fields are related to plasma density gradients is investigated in this study using Cluster data. Of the 41 events investigated, 27 are monopolar or bipolar electric field events occurring at density gradients. 11 of these are monopolar events and all except one are found to be associated with the sharp density gradient at the polar cap boundary of the plasma sheet. All the 16 bipolar events are found at density gradients in the plasma sheet. The difference is interpreted to be due to the possibility of closing the field-aligned currents, associated with the intense electric fields, via Pedersen currents in the ionosphere. If there are relatively dense plasma populations on both sides of the gradient, Pedersen currents can float in two directions. If there is a thin plasma on one side (polar cap), the Pedersen current can mainly float in the other direction (equatorward).
DE: 2704 Auroral phenomena (2407)
DE: 2712 Electric fields (2411)
DE: 2764 Plasma sheet
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005