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| Titel |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
| VerfasserIn |
R. Rüster, K. Schlegel |
| 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. 10 ; Nr. 17, no. 10, S.1284-1292 |
| Datensatznummer |
250013823
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| Publikation (Nr.) |
 copernicus.org/angeo-17-1284-1999.pdf |
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| Zusammenfassung |
Backscatter from E-region irregularities was
observed at aspect angles close to 90° (almost parallel to the direction of the
magnetic field) using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric
fields and increased E-region electron temperatures simultaneously measured with
the incoherent scatter facility EISCAT proved that the Farley-Buneman plasma
instability was excited. In addition, strong particle precipitation was present
as inferred from EISCAT electron densities indicating that the gradient drift
instability may have been active, too. Backscatter at such large aspect angles
was not expected and has not been observed before. The characteristics of the
observed echoes, however, are in many aspects completely different from usual
auroral radar results: the Doppler velocities are only of the order of 10 m/s,
the half-width of the spectra is around 5 m/s, the echoes originate at altitudes
well below 100 km, and they seem to be not aspect-sensitive with respect to the
magnetic field direction. We, therefore, conclude that the corresponding
irregularities are not caused by the mentioned instabilities and that other
mechanism have to be invoked.
Key words. Ionosphere (plasma waves and instabilities;
ionosphere irregularities; particle precipitaion) · Meteorology and atmospheric
dynamics (middle atmosphere dynamics) |
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