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| Titel |
Properties of standing Kruskal-Schwarzschild-modes at the magnetopause |
| VerfasserIn |
F. Plaschke, K.-H. Glassmeier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 29, no. 10 ; Nr. 29, no. 10 (2011-10-14), S.1793-1807 |
| Datensatznummer |
250017107
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| Publikation (Nr.) |
 copernicus.org/angeo-29-1793-2011.pdf |
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| Zusammenfassung |
| The radial, oscillatory motion of the Earth's magnetopause has been found to
occur predominantly with some distinct, sometimes called "magic"
frequencies, which have been attributed to magnetospheric wave guide modes,
typical solar wind variations or, more recently, surface waves on the
magnetopause standing between the northern and southern ionospheres. In this
paper we present for the first time a derivation of these surface waves,
denominated as Kruskal-Schwarzschild-modes (KS-modes), in the approximation
of the ideal, single-fluid magnetohydrodynamic theory for incompressible
plasmas. The calculations are performed in the simplified geometry of the box
magnetosphere with the magnetopause being a plane between two plasma regimes
of homogeneous conditions. The reflection of the KS-modes at the ionospheres
is being discussed. Under the given assumptions and realistic conditions the
validity of the calculations is shown to be limited to cases of parallel or
anti-parallel background magnetic fields on both sides of the magnetopause,
respectively. For these cases a detailed discussion of the mode structure is
presented. The magnetopause when affected by a KS-mode is found to resemble a
membrane under tension with respect to its motion; the ionospheres act as
supporting points of the membrane and the KS-modes correspond in this picture
to their eigenmodes of oscillation. Localized pressure enhancements in the
magnetosheath are discussed as possible excitation mechanism for the
KS-modes. |
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