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Ann. Geophys., 21, 1083-1093, 2003
www.ann-geophys.net/21/1083/2003/
© European Geosciences Union 2003
Penetration of magnetosonic waves into the magnetosphere: influence of a transition layer
A. S. Leonovich1,3, V. V. Mishin1,3, and J. B. Cao2,3
1Institute of Solar-Terrestrial Physics (ISTP), Russian Academy of Science, Siberian Branch, Irkutsk 33, P.O.Box 4026, 664033, Russia
2Center for Space Science and Applied Research, Chinese Academy of Science, China
3Russian-Chinese Joint Research Center on Space Weather, China
Abstract. We have constructed a
theory for the penetration of magnetosonic waves from the solar wind into the
magnetosphere through a transition layer in a plane-stratified model for the
medium. In this model the boundary layer is treated as a region, inside of
which the parameters of the medium vary from values characteristic for the
magnetosphere, to values typical of the solar wind. It is shown that if such a
layer has sufficiently sharp boundaries, then magnetosonic eigen-oscillations
can be excited inside of it. The boundaries of such a layer are partially
permeable for magnetosonic waves. Therefore, if the eigen-oscillations are not
sustained by an external source, they will be attenuated, because some of the
energy is carried away by the oscillations that penetrate the solar wind and
the magnetosphere. It is shown that about 40% of the energy flux of the waves
incident on the transition layer in the magnetotail region penetrate to the
magnetosphere’s interior. This energy flux suffices to sustain the stationary
convection of magnetospheric plasma. The total energy input to the
magnetosphere during a time interval of the order of the substorm growth phase
time is comparable with the energetics of an average substorm.
Key words. Magnetospheric physics (MHD
waves and instabilities; solar wind–magnetosphere interactions) – Space
plasma physics (kinetic and MHD theory)
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