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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 25, issue 8
Ann. Geophys., 25, 1877–1885, 2007
https://doi.org/10.5194/angeo-25-1877-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 25, 1877–1885, 2007
https://doi.org/10.5194/angeo-25-1877-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.

  29 Aug 2007

29 Aug 2007

Ion escape from the high latitude magnetopause: analysis of oxygen and proton dynamics in the presence of magnetic turbulence

A. Taktakishvili1,*, G. Zimbardo2, E. Amata3, S. Savin4, A. Greco2, P. Veltri2, and R. E. Lopez5 A. Taktakishvili et al.
  • 1Center for Plasma Astrophysics, Tbilisi, Georgia
  • 2Universitá della Calabria, Cosenza, Italy
  • 3Istituto di Fisica dello Spazio Interplanetario, INAF, Roma, Italy
  • 4Space Research Institute, Moscow, Russia
  • 5Florida Institute of Technology, Melbourne, FL, USA
  • *also at: Goddard Space Flight Center, Greenbelt, MD, USA

Abstract. Recent Cluster observations of the vicinity of the high latitude magnetopause indicate the presence of beams of singly charged oxygen ions, which are of ionospheric origin. In this paper we examine the role of magnetic turbulence combined with a dc electric field across the magnetopause in causing the cross field transport of protons and of singly charged oxygen ions, by means of a kinetic test particle simulation. We find that the observed values of magnetosheath turbulence and electric fields can produce a substantial escape of the oxygen ions relative to protons. By varying the magnetic turbulence level in the simulation, we find that the number of O+ crossing the magnetopause grows with δB/B0, and that very few ions can cross the magnetopause for δB/B0=0. The ion temperature also grows with δB/B0, showing that magnetic turbulence is effective in thermalizing the kinetic energy gain due to the cross-magnetopause potential drop. We suggest that this mechanism can help to explain Cluster observations of energetic oxygen ions during a high-latitude magnetopause crossing.

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