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| Titel |
Quasiperiodic ULF-pulsations in Saturn's magnetosphere |
| VerfasserIn |
G. Kleindienst, K.-H. Glassmeier, S. Simon, M. K. Dougherty, N. Krupp |
| 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 ; 27, no. 2 ; Nr. 27, no. 2 (2009-02-23), S.885-894 |
| Datensatznummer |
250016423
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| Publikation (Nr.) |
 copernicus.org/angeo-27-885-2009.pdf |
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| Zusammenfassung |
| Recent magnetic field investigations made onboard the Cassini spacecraft in
the magnetosphere of Saturn show the existence of a variety of ultra low
frequency plasma waves. Their frequencies suggest that they are presumably
not eigenoscillations of the entire magnetospheric system, but excitations
confined to selected regions of the magnetosphere. While the main magnetic
field of Saturn shows a distinct large scale modulation of approximately
2 nT with a periodicity close to Saturn's rotation period, these ULF
pulsations are less obvious superimposed oscillations with an amplitude
generally not larger than 3 nT and show a package-like structure. We have
analyzed these wave packages and found that they are correlated to a certain
extent with the large scale modulation of the main magnetic field. The
spatial localization of the ULF wave activity is represented with respect to
local time and Kronographic coordinates. For this purpose we introduce a
method to correct the Kronographic longitude with respect to a rotation
period different from its IAU definition. The observed wave packages occur in
all magnetospheric regions independent of local time, elevation, or radial
distance. Independent of the longitude correction applied the wave packages
do not occur in an accentuated Kronographic longitude range, which implies
that the waves are not excited or confined in the same selected longitude
ranges at all times or that their lifetime leads to a variable phase with
respect to the longitudes where they have been exited. |
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