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| Titel |
High-latitude HF Doppler observations of ULF waves. 1. Waves with large spatial scale sizes |
| VerfasserIn |
D. M. Wright, T. K. Yeoman, P. J. Chapman |
| 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. 12 ; Nr. 15, no. 12, S.1548-1556 |
| Datensatznummer |
250013039
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1548-1997.pdf |
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| Zusammenfassung |
A quantitative study of observations of the
ionospheric signatures of magnetospheric ultra low frequency (ULF) waves by a
high-latitude (geographic: 69.6°N 19.2°E) high-frequency Doppler sounder has
been undertaken. The signatures, which are clearly correlated with pulsations in
ground magnetometer data, exhibit periods in the range 100–400 s and have
azimuthal wave numbers in the range 3–8. They are interpreted here as local
field line resonances. Phase information provided by O- and X-mode Doppler data
support the view that these are associated with field line resonances having
large azimuthal scale sizes. The relative phases and amplitudes of the
signatures in the Doppler and ground magnetometer data are compared with a model
for the generation of Doppler signatures from incident ULF waves. The outcome
suggests that the dominant mechanism involved in producing the Doppler signature
is the vertical component of an E × B bulk
motion of the local plasma caused by the electric field perturbation of the ULF
wave.
Key words. Auroral ionosphere ·
Magnetosphere-ionosphere interactions · MHD waves and instabilities HF Doppler
· ULF Waves |
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