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| Titel |
Long-term lidar observations of wintertime gravity wave activity over northern Sweden |
| VerfasserIn |
B. Ehard, P. Achtert, J. Gumbel |
| 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 ; 32, no. 11 ; Nr. 32, no. 11 (2014-11-13), S.1395-1405 |
| Datensatznummer |
250121130
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| Publikation (Nr.) |
 copernicus.org/angeo-32-1395-2014.pdf |
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| Zusammenfassung |
| This paper presents an analysis of gravity wave activity over northern Sweden
as deduced from 18 years of wintertime lidar measurements at Esrange
(68° N, 21° E). Gravity wave potential energy density
(GWPED) was used to characterize the strength of gravity waves in the
altitude regions 30–40 km and 40–50 km. The obtained values exceed
previous observations reported in the literature. This is suggested to be due
to Esrange's location downwind of the Scandinavian mountain range and due to
differences in the various methods that are currently used to retrieve
gravity wave parameters. The analysis method restricted the identification of
the dominating vertical wavelengths to a range from 2 to 13 km. No
preference was found for any wavelength in this window. Monthly mean values
of GWPED show that most of the gravity waves' energy dissipates well below
the stratopause and that higher altitude regions show only small dissipation
rates of GWPED. Our analysis does not reproduce the previously reported
negative trend in gravity wave activity over Esrange. The observed
inter-annual variability of GWPED is connected to the occurrence of
stratospheric warmings with generally lower wintertime mean GWPED during
years with major stratospheric warmings. A bimodal GWPED occurrence frequency
indicates that gravity wave activity at Esrange is affected by both
ubiquitous wave sources and orographic forcing. |
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