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| Titel |
Stratospheric sudden warming effects on winds and temperature in the middle atmosphere at middle and low latitudes: a study using WACCM |
| VerfasserIn |
A. Chandran, R. L. Collins |
| 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. 7 ; Nr. 32, no. 7 (2014-07-28), S.859-874 |
| Datensatznummer |
250121086
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| Publikation (Nr.) |
 copernicus.org/angeo-32-859-2014.pdf |
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| Zusammenfassung |
| A stratospheric sudden warming (SSW) is a dynamical phenomenon of the
wintertime stratosphere caused by the interaction between planetary Rossby
waves propagating from the troposphere and the stratospheric zonal-mean flow.
While the effects of SSW events are seen predominantly in high latitudes,
they can also produce significant changes in middle and low latitude
temperature and winds. In this study we quantify the middle and low latitude
effects of SSW events on temperature and zonal-mean winds using a composite
of SSW events between 1988 and 2010 simulated with the specified dynamics
version of the Whole Atmosphere Community Climate Model (WACCM). The
temperature and wind responses seen in the tropics also extend into the low
latitudes in the other hemisphere. There is variability in observed zonal-mean winds and temperature depending on the observing location within the
displaced or split polar vortex and propagation direction of the planetary
waves. The propagation of planetary waves show that they originate in
mid–high latitudes and propagate upward and equatorward into the mid-latitude
middle atmosphere where they produce westward forcing reaching peak values of
~ 60–70 m s−1 day−1. These propagation paths in the
lower latitude stratosphere appear to depend on the phase of the quasi-biennial oscillation (QBO). During
the easterly phase of the QBO, waves originating at high latitudes propagate
across the equator, while in the westerly phase of the QBO, the planetary
waves break at ~ 20–25° N and there is no propagation across
the equator. The propagation of planetary waves across the equator during the
easterly phase of the QBO reduces the tropical upwelling and poleward flow in
the upper stratosphere. |
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