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Titel Ionospheric conductance distribution and MHD wave structure: observation and model
VerfasserIn F. Budnik, M. Stellmacher, K.-H. Glassmeier, S. C. Buchert
Medientyp Artikel
Sprache Englisch
ISSN 0992-7689
Digitales Dokument URL
Erschienen In: Annales Geophysicae ; 16, no. 2 ; Nr. 16, no. 2, S.140-147
Datensatznummer 250013150
Publikation (Nr.) Volltext-Dokument vorhandencopernicus.org/angeo-16-140-1998.pdf
 
Zusammenfassung
The ionosphere influences magnetohydrodynamic waves in the magnetosphere by damping because of Joule heating and by varying the wave structure itself. There are different eigenvalues and eigensolutions of the three dimensional toroidal wave equation if the height integrated Pedersen conductivity exceeds a critical value, namely the wave conductance of the magnetosphere. As a result a jump in frequency can be observed in ULF pulsation records. This effect mainly occurs in regions with gradients in the Pedersen conductances, as in the auroral oval or the dawn and dusk areas. A pulsation event recorded by the geostationary GOES-6 satellite is presented. We explain the observed change in frequency as a change in the wave structure while crossing the terminator. Furthermore, selected results of numerical simulations in a dipole magnetosphere with realistic ionospheric conditions are discussed. These are in good agreement with the observational data.

Key words. Ionosphere · (Ionosphere · magnetosphere interactions) · Magnetospheric physics · Magnetosphere · ionosphere interactions · MHD waves and instabilities.
 
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