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| Titel |
Flow angle dependence for the asymmetry of broad 50-MHz coherent echoes at large magnetic aspect angles |
| VerfasserIn |
A. V. Kustov, G. J. Sofko, J. A. Koehler, M. V. Uspensky |
| 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. 6 ; Nr. 15, no. 6, S.760-766 |
| Datensatznummer |
250012837
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| Publikation (Nr.) |
 copernicus.org/angeo-15-760-1997.pdf |
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| Zusammenfassung |
| The skewness of broad Type 2-like spectra has
been studied using data collected by two orthogonal CW 50-MHz radio links with
co-located scattering volumes. Geometrical aspect angles of observations were
about 10°. One short event was considered. For this event, the electron flow
direction was changing periodically (period about 9 minutes) presumably due to
the passage of a magnetospheric MHD wave through the ionosphere. It was found
that for the radar observations along the electrojet flow, the skewness had the
same sign as the mean Doppler shift with average absolute values in between
0.5-1.0. For observations perpendicular to the electrojet flow, spectra were
more symmetrical (average skewness was around 0) and the sign of the skewness
was sometimes opposite to the sign of the mean Doppler shift. These observations
are interpreted in terms of contribution from both the Farley-Buneman and
gradient-drift instabilities to the resultant spectrum. Differences with radar
observations at small aspect angles are discussed. |
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