HR: 14:55h
AN: SM22C-06    [PDF]
TI: Temporal and Spatial Characteristics of Acceleration Structures in the Auroral Return Current Region
AU: * Marklund, G T
EM: marklund@plasma.kth.se
AF: Alfven Laboratory, Royal Institute of Technology, Stockholm, SE10044 Sweden
AU: Karlsson, T
EM: tkarlsson@plasma.kth.se
AF: Alfven Laboratory, Royal Institute of Technology, Stockholm, SE10044 Sweden
AU: Figueiredo, S
EM: figueiredo@plasma.kth.se
AF: Alfven Laboratory, Royal Institute of Technology, Stockholm, SE10044 Sweden
AU: Johansson, T
EM: tjohansson@plasma.kth.se
AF: Alfven Laboratory, Royal Institute of Technology, Stockholm, SE10044 Sweden
AU: Buchert, S
EM: scb@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, SE-75121 Sweden
AB: Temporal and spatial characteristics of high-altitude auroral electric fields, and, in particular, those which are related to quasi-static auroral electric potential structures, are discussed using Cluster multi-point observations from auroral field line crossings at geocentric distances of about 5 RE. Intense and narrow-structured diverging electric fields, associated with upward accelerated electrons, being fingerprints of quasi-static acceleration structures in the auroral return current region, appear more frequently at these altitudes than their counterpart, converging electric fields, on auroral field lines, for reasons not yet understood. The time needed for evacuating ionospheric electrons at the ionospheric end of the return current flux tube, which depend on the field-aligned current density, represent one characteristic time scale for the accelerating electric fields. We present results from four Cluster encounters with such acceleration structures and how these and their associated field-aligned current and electron distributions, evolve on the different time scales given by different inter-spacecraft separation distances.
DE: 2704 Auroral phenomena (2407)
DE: 2708 Current systems (2409)
DE: 2712 Electric fields (2411)
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting