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AGU: Journal of Geophysical Research, Space Physics

 

Keywords

  • magnetic vortices
  • magnetosheath
  • turbulence

Index Terms

  • Magnetospheric Physics: Magnetosheath
  • Space Plasma Physics: MHD waves and instabilities
  • Space Plasma Physics: Neutral particles
  • Space Plasma Physics: Turbulence
Abstract
Cited By (20)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, A12208, 14 PP., 2006
doi:10.1029/2006JA011934

Alfvén vortex filaments observed in magnetosheath downstream of a quasi-perpendicular bow shock

O. Alexandrova

Observatoire de Paris-Meudon, Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Centre National de la Recherche Scientifique, Meudon, France

A. Mangeney

Observatoire de Paris-Meudon, Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Centre National de la Recherche Scientifique, Meudon, France

M. Maksimovic

Observatoire de Paris-Meudon, Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Centre National de la Recherche Scientifique, Meudon, France

N. Cornilleau-Wehrlin

Centre d'Etude des Environnements Terrestre et Plantaires, L'Institut Pierre-Simon Laplace, Vélizy, France

J.-M. Bosqued

Centre d'Etude Spatiale des Rayonnements, Centre National de la Recherche Scientifique, Toulouse, France

M. André

Swedish Institute of Space Physics, Umeiå University, Umeiå, Sweden

Magnetic field fluctuations in the frequency range [0.02–12.5] Hz are studied with the four Cluster satellites in the Earth magnetosheath downstream of a quasi-perpendicular bow shock. The turbulent spectrum presents a spectral break accompanied by a broad maximum usually interpreted as due to Alfvén ion cyclotron waves. In this paper we establish that this spectral knee corresponds to space-localized coherent magnetic structures in the form of Alfvén vortices. The Alfvén vortex is a nonlinear cylindrical Alfvén wave, quasi-parallel to the mean magnetic field B 0 and propagating in a plane perpendicular to B 0. In this plane the observed vortices are localized within 20c/ω pi . The frequent observations of such structures indicate their stability in the plasma. Therefore the Alfvén vortices can be an important element in the magnetosheath turbulence. The possible origins of these vortices, such as a strong turbulence or the filamentation instability of an Alfvén wave, are discussed.

Received 23 June 2006; accepted 31 August 2006; published 15 December 2006.

Citation: Alexandrova, O., A. Mangeney, M. Maksimovic, N. Cornilleau-Wehrlin, J.-M. Bosqued, and M. André (2006), Alfvén vortex filaments observed in magnetosheath downstream of a quasi-perpendicular bow shock, J. Geophys. Res., 111, A12208, doi:10.1029/2006JA011934.

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