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| Titel |
First experimental verification of summertime mesospheric momentum balance based on radar wind measurements at 69° N |
| VerfasserIn |
M. Placke, P. Hoffmann, M. Rapp |
| 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 ; 33, no. 9 ; Nr. 33, no. 9 (2015-09-10), S.1091-1096 |
| Datensatznummer |
250121243
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| Publikation (Nr.) |
 copernicus.org/angeo-33-1091-2015.pdf |
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| Zusammenfassung |
| Gravity waves (GWs) greatly influence the background state of the middle
atmosphere by imposing their momentum on the mean flow upon breaking and by
thus driving, e.g., the upper mesospheric summer zonal wind reversal. In
this situation momentum is conserved by a balance between the vertical
divergence of GW momentum flux (the so-called GW drag) and the Coriolis
acceleration of the mean meridional wind. In this study, we present first
quantitative mean annual cycles of these two balancing quantities from the
medium frequency Doppler radar at the polar site Saura (SMF radar,
69° N, 16° E). Three-year means for 2009 through 2011 clearly
show that the observed zonal momentum balance between 70 and 100 km with
contributions from GWs only is fulfilled during summer when GW activity is
strongest and more stable than in winter. During winter, the balance between
GW drag and Coriolis acceleration of the mean meridional wind is not
existent, which is likely due to the additional contribution from planetary waves, which
are not considered by the present investigation. The differences in the
momentum balance between summer and winter conditions are additionally
clarified by 3-month mean vertical profiles for summer 2010 and winter
2010/2011. |
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