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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 24, issue 6
Ann. Geophys., 24, 1713–1723, 2006
https://doi.org/10.5194/angeo-24-1713-2006
© Author(s) 2006. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 24, 1713–1723, 2006
https://doi.org/10.5194/angeo-24-1713-2006
© Author(s) 2006. This work is distributed under
the Creative Commons Attribution 3.0 License.

  03 Jul 2006

03 Jul 2006

On the profile of intense high-altitude auroral electric fields at magnetospheric boundaries

T. Johansson1, G. Marklund1, T. Karlsson1, S. Liléo1, P.-A. Lindqvist1, A. Marchaudon2, H. Nilsson3, and A. Fazakerley4 T. Johansson et al.
  • 1Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, Sweden
  • 2LPCE/CNRS, Orleans Cedex, France
  • 3Swedish Institute of Space Physics, Kiruna, Sweden
  • 4Mullard Space Science Laboratory, University College, London, UK

Abstract. The profile of intense high-altitude electric fields on auroral field lines has been studied using Cluster data. A total of 41 events with mapped electric field magnitudes in the range between 0.5–1 V/m were examined, 27 of which were co-located with a plasma boundary, defined by gradients in particle flux, plasma density and plasma temperature. Monopolar electric field profiles were observed in 11 and bipolar electric field profiles in 16 of these boundary-associated electric field events. Of the monopolar fields, all but one occurred at the polar cap boundary in the late evening and midnight sectors, and the electric fields were typically directed equatorward, whereas the bipolar fields all occurred at plasma boundaries clearly within the plasma sheet. These results support the prediction by Marklund et al. (2004), that the electric field profile depends on whether plasma populations, able to support intense field-aligned currents and closure by Pedersen currents, exist on both sides, or one side only, of the boundary.

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