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| Titel |
A comparison of field-line resonances observed at the Goose Bay and Wick radars |
| VerfasserIn |
G. Provan, T. K. Yeoman |
| 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 ; 15, no. 2 ; Nr. 15, no. 2, S.231-235 |
| Datensatznummer |
250012630
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| Publikation (Nr.) |
 copernicus.org/angeo-15-231-1997.pdf |
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| Zusammenfassung |
| Previous observations with the Goose Bay HF
coherent-scatter radar have revealed structured spectral peaks at ultra-low
frequencies. The frequencies of these spectral peaks have been demonstrated to
be extremely consistent from day to day. The stability of these spectral peaks
can be seen as evidence for the existence of global magnetospheric cavity modes
whose resonant frequencies are independent of latitude. Field-line resonances
occur when successive harmonics of the eigenfrequency of the magnetospheric
cavity or waveguide match either the first harmonic eigenfrequency of the
geomagnetic field lines or higher harmonics of this frequency. Power spectra
observed at the SABRE VHF coherent-scatter radar at Wick, Scotland, during night
and early morning are revealed to show similarly clearly structured spectral
peaks. These spectral peaks are the result of local field-line resonances due to
Alfvén waves standing on magnetospheric field lines. A comparison of the
spectra observed by the Goose Bay and Wick radars demonstrate that the
frequencies of the field-line resonances are, on average, almost identical,
despite the different latitudinal ranges covered by the two radars. Possible
explanations for the similarity of the signatures on the two radar systems are
discussed. |
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