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| Titel |
The impact of planetary waves on the latitudinal displacement of sudden stratospheric warmings |
| VerfasserIn |
V. Matthias, P. Hoffmann, A. Manson, C. Meek, G. Stober, P. Brown, 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 ; 31, no. 8 ; Nr. 31, no. 8 (2013-08-09), S.1397-1415 |
| Datensatznummer |
250086093
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1397-2013.pdf |
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| Zusammenfassung |
| The Northern Hemispheric winter is disturbed by large scale variability
mainly caused by Planetary Waves (PWs), which interact with the mean flow and
thus result in Sudden Stratospheric Warmings (SSWs). The effects of a SSW on
the middle atmosphere are an increase of stratospheric and a simultaneous
decrease of mesospheric temperature as well as a wind reversal to westward
wind from the mesosphere to the stratosphere. In most cases these
disturbances are strongest at polar latitudes, get weaker toward the south
and vanish at mid-latitudes around 50° to 60° N as for example during
the winter 2005/06. However, other events like in 2009, 2010 and 2012 show a
similar or even stronger westward wind at mid- than at polar latitudes either
in the mesosphere or in the stratosphere during the SSW. This study uses
local meteor and MF-radar measurements, global satellite observations from
the Microwave Limb Sounder (MLS) and assimilated model data from MERRA
(Modern-ERA Retrospective analysis for research and Applications). We compare
differences in the latitudinal structure of the zonal wind, temperature and
PW activity between a "normal" event, where the event in 2006 was chosen
representatively, and the latitudinal displaced events in 2009, 2010 and
2012. A continuous westward wind band between the pole and 20° N is
observed during the displaced events. Furthermore, distinctive temperature
differences at mid-latitudes occur before the displaced warmings compared to
2006 as well as a southward extended stratospheric warming afterwards. These
differences between the normal SSW in 2006 and the displaced events in 2009,
2010 and 2012 are linked to an increased PW activity between 30° N and
50° N and the changed stationary wave flux in the stratosphere around
the displaced events compared to 2006. |
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