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| Titel |
Spectral structure of Pc3–4 pulsations: possible signatures of cavity modes |
| VerfasserIn |
P. R. Sutcliffe, B. Heilig, S. Lotz |
| 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 ; 31, no. 4 ; Nr. 31, no. 4 (2013-04-23), S.725-743 |
| Datensatznummer |
250019028
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| Publikation (Nr.) |
 copernicus.org/angeo-31-725-2013.pdf |
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| Zusammenfassung |
| In this study we investigate the spectral structure of Pc3–4 pulsations
observed at low and midlatitudes. For this purpose, ground-based
magnetometer data recorded at the MM100 stations in Europe and at two low
latitude stations in South Africa were used. In addition, fluxgate
magnetometer data from the CHAMP (CHAllenging Minisatellite Payload) low Earth orbit satellite were used. The
results of our analysis suggest that at least three mechanisms contribute to
the spectral content of Pc3–4 pulsations typically observed at these
latitudes. We confirm that a typical Pc3–4 pulsation contains a field line
resonance (FLR) contribution, with latitude dependent frequency, and an
upstream wave (UW) contribution, with frequency proportional to the IMF (interplanetary magnetic field)
magnitude BIMF. Besides the FLR and UW contributions, the Pc3–4
pulsations consistently contain signals at other frequencies that are
independent of latitude and BIMF. We suggest that the most likely
explanation for these additional frequency contributions is that they are
fast mode resonances (FMRs) related to cavity, waveguide, or virtual modes.
Although the above contributions to the pulsation spectral structure have
been reported previously, we believe that this is the first time where
evidence is presented showing that they are all present simultaneously in
both ground-based and satellite data. |
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