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| Titel |
Observations of thermospheric neutral winds within the polar cusp and the auroral oval using a Doppler imaging system (DIS) |
| VerfasserIn |
D. Rees, R. W. Smith, F. Signernes, K. Henriksen, U. Brandstrom, M. Harris, G. Maskall |
| 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 ; 16, no. 11 ; Nr. 16, no. 11, S.1461-1474 |
| Datensatznummer |
250013543
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| Publikation (Nr.) |
 copernicus.org/angeo-16-1461-1998.pdf |
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| Zusammenfassung |
Two Doppler imaging systems (DIS) or
wide-field imaging Fabry-Perot interferometers (FPI), have recently been
commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard,
and the second at the IRF, Kiruna, Sweden. These instruments can provide
wide-field (600 * 800 km) images of neutral wind flows in the upper
thermosphere, by measuring the Doppler shift of the atomic oxygen forbidden near
630 nm, which is emitted from an altitude of approximately 240 km. From the
instrument in Svalbard, at mid-winter, it is possible to observe the dayside
polar cusp and the polar cap throughout the entire day, whereas from Kiruna, the
night-time auroral oval is observable during the hours of darkness. Measurements
of thermospheric dynamics from the DIS can be used in conjunction with
observations of ionospheric plasma flows and thermal plasma densities by the
EISCAT-Svalbard radar (ESR) and by EISCAT, along with other complementary
observations by co-located instruments such as the auroral large-scale imaging
system (ALIS). Such combined data sets will allow a wide range of scientific
studies to be performed concerning the dynamical response of the thermosphere
and ionosphere, and the important energetic and momentum exchange processes
resulting from their complex interactions. These processes are particularly
important in the immediate vicinity of the polar cusp and within the auroral
oval. Early results from Svalbard in late 1995 will be discussed. The DIS in
Kiruna observed two interesting geomagnetic disturbances in early 1997, the
minor geomagnetic storm of 10, 11 January, and the disturbed period from 7–10
February. During these events, the thermospheric wind response showed some
interesting departures from the average behaviour, which we attribute to the
result of strong and variable Lorenz forcing (ion drag) and Joule and particle
heating during these geomagnetic disturbances.
Key words. Ionosphere (Polar ionosphere) · Meteorology
and atmospheric dynamics (thermospheric dynamics; instruments and techniques). |
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