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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 26, issue 8
Ann. Geophys., 26, 2371–2382, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: STAMMS: Spatio-Temporal Analysis and Multipoint Measurements...

Ann. Geophys., 26, 2371–2382, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

  05 Aug 2008

05 Aug 2008

Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

S. Haaland1,2,*, G. Paschmann2, M. Förster3, J. Quinn4,**, R. Torbert4, H. Vaith4, P. Puhl-Quinn4, and C. Kletzing5 S. Haaland et al.
  • 1Max-Planck-Institut für extraterrestrische Physik, Garching, Germany
  • 2Department of Physics, University of Bergen, Norway
  • 3GeoForschungsZentrum Potsdam, Potsdam, Germany
  • 4University of New Hampshire, Durham, NH 03824, USA
  • 5University of Iowa, Iowa City, IA 52242, USA
  • *now at: Max-Planck-Institut für Sonnensystemforschung, Lindau, Germany
  • **now at: Boston University, Boston, MA 02215, USA

Abstract. A major part of the plasma in the Earth's magnetotail is populated through transport of plasma from the solar wind via the magnetotail lobes. In this paper, we present a statistical study of plasma convection in the lobes for different directions of the interplanetary magnetic field and for different geomagnetic disturbance levels. The data set used in this study consists of roughly 340 000 one-minute vector measurements of the plasma convection from the Cluster Electron Drift Instrument (EDI) obtained during the period February 2001 to June 2007. The results show that both convection magnitude and direction are largely controlled by the interplanetary magnetic field (IMF). For a southward IMF, there is a strong convection towards the central plasma sheet with convection velocities around 10 km s−1. During periods of northward IMF, the lobe convection is almost stagnant. A By dominated IMF causes a rotation of the convection patterns in the tail with an oppositely directed dawn-dusk component of the convection for the northern and southern lobe. Our results also show that there is an overall persistent duskward component, which is most likely a result of conductivity gradients in the footpoints of the magnetic field lines in the ionosphere.

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