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| Titel |
High-latitude HF Doppler observations of ULF waves: 2. Waves with small spatial scale sizes |
| VerfasserIn |
D. M. Wright, 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 ; 17, no. 7 ; Nr. 17, no. 7, S.868-876 |
| Datensatznummer |
250013783
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| Publikation (Nr.) |
 copernicus.org/angeo-17-868-1999.pdf |
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| Zusammenfassung |
The DOPE (Doppler Pulsation Experiment) HF
Doppler sounder located near Tromsø, Norway (geographic: 69.6°N 19.2°E; L
= 6.3) is deployed to observe signatures, in the high-latitude ionosphere, of
magnetospheric ULF waves. A type of wave has been identified which exhibits no
simultaneous ground magnetic signature. They can be subdivided into two classes
which occur in the dawn and dusk local time sectors respectively. They generally
have frequencies greater than the resonance fundamentals of local field lines.
It is suggested that these may be the signatures of high-m ULF waves
where the ground magnetic signature has been strongly attenuated as a result of
the scale size of the waves. The dawn population demonstrate similarities to a
type of magnetospheric wave known as giant (Pg) pulsations which tend to be
resonant at higher harmonics on magnetic field lines. In contrast, the waves
occurring in the dusk sector are believed to be related to the storm-time Pc5s
previously reported in VHF radar data. Dst measurements support these
observations by indicating that the dawn and dusk classes of waves occur
respectively during geomagnetically quiet and more active intervals.
Key words. Ionosphere (auroral ionosphere;
ionosphere-magnetosphere interactions) · Magnetospheric physics (MHD waves and
instabilities) |
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