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Ann. Geophys., 22, 993-999, 2004
www.ann-geophys.net/22/993/2004/
© European Geosciences Union 2004
Interchange instability of a curved current layerconvecting in the magnetosheath from the bow shock towards themagnetopause
I. L. Arshukova1, N. V. Erkaev1, and H. K. Biernat2,3
1Institute of Computational Modelling, Russian Academy of Sciences, Krasnoyarsk-36, 660036, Russia
2Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
3also at: Institute of Geophysics, Astrophysics, and Meteorology, University of Graz, 8010 Graz, Austria
Abstract. This paper deals with nonsteady perturbations of the magnetosheath
parameters which are related to variations of the interplanetary
magnetic field from north to south under a constant solar wind
dynamic pressure. The magnetic field changes its direction within
a thin layer which is convected with the plasma from the bow shock
to the ionopause. In the course of time, this current layer is
amplified during its motion towards the magnetopause. The
intensity of the current is increasing, the layer thickness is
decreasing, and the gradients of parameters are becoming much
sharper while the layer is approaching the magnetopause. The
curvature radius of this layer is decreasing while it is draping
around the magnetopause. This curved layer structure with reversed magnetic field in the
magnetosheath is found to be unstable with respect to the
interchange instability. The growth rate of the instability is
obtained for different positions of the layer.
Key words. Magnetospheric physics (magnetosheath)
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