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| Titel |
Generation of the lower-thermospheric vertical wind estimated with the EISCAT KST radar at high latitudes during periods of moderate geomagnetic disturbance |
| VerfasserIn |
S. Oyama, B. J. Watkins, S. Maeda, H. Shinagawa, S. Nozawa, Y. Ogawa, A. Brekke, C. Lathuillere, W. Kofman |
| 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 ; 26, no. 6 ; Nr. 26, no. 6 (2008-06-11), S.1491-1505 |
| Datensatznummer |
250016120
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| Publikation (Nr.) |
 copernicus.org/angeo-26-1491-2008.pdf |
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| Zusammenfassung |
| Lower-thermospheric winds at high latitudes during moderately-disturbed
geomagnetic conditions were studied using data obtained with the European
Incoherent Scatter (EISCAT) Kiruna-Sodankylä-Tromsø (KST) ultrahigh
frequency (UHF) radar system on 9–10 September 2004. The antenna-beam
configuration was newly designed to minimize the estimated measurement error
of the vertical neutral-wind speed in the lower thermosphere. This method
was also available to estimate the meridional and zonal components. The
vertical neutral-wind speed at 109 km, 114 km, and 120 km heights showed
large upward motions in excess of 30 m s−1 in association with an
ionospheric heating event. Large downward speeds in excess of −30 m s−1
were also observed before and after the heating event. The meridional
neutral-wind speed suddenly changed its direction from equatorward to
poleward when the heating event began, and then returned equatorward
coinciding with a decrease in the heating event. The magnetometer data from
northern Scandinavia suggested that the center of the heated region was
located about 80 km equatorward of Tromsø. The pressure gradient caused
the lower-thermospheric wind to accelerate obliquely upward over Tromsø
in the poleward direction. Acceleration of the neutral wind flowing on a
vertically tilted isobar produced vertical wind speeds larger by more than
two orders of magnitude than previously predicted, but still an order of
magnitude smaller than observed speeds. |
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