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| Titel |
The annual cycle in lower stratospheric temperatures revisited |
| VerfasserIn |
S. Fueglistaler, P. H. Haynes, P. M. Forster |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 8 ; Nr. 11, no. 8 (2011-04-21), S.3701-3711 |
| Datensatznummer |
250009643
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| Publikation (Nr.) |
 copernicus.org/acp-11-3701-2011.pdf |
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| Zusammenfassung |
| Observed lower stratospheric temperatures show a
prominent annual cycle. The cycles in the tropics and Northern
Hemisphere are in phase and the cycle in the Southern Hemisphere has
the opposite phase.
In an elegant and influential paper, Yulaeva, Holton and Wallace (1994) explained the observed pattern as a direct consequence
of hemispheric asymmetries in the dynamical forcing of the
stratospheric circulation. They showed that in
Microwave Sounding Unit channel 4 (weighting
centered in the lower stratosphere) data the combined extratropical
and the tropical temperature cycle nearly compensate and interpreted
the out-of-phase temperature variations between tropics and
extratropics as the
temperature response to an annual cycle
in the wave driven residual circulation.
We show that the near-compensation of temperature variations
observed by Yulaeva et al. (1994)
is artefact of the weighting
function of the MSU-4 channel and does not hold on individual pressure
levels.
We discuss in detail the conditions required that temperature
variations compensate, and what insights can be obtained from
analysis of tropical, extratropical and global mean temperature
variations.
Dynamically induced seasonal variations of lower stratospheric
ozone lead to an amplification of the seasonal
temperature cycle particularly in the tropics. The
latitudinal structure of
static stability also
induces a significant deviation from compensation of
tropical and combined extratropical temperature variations.
In line with Yulaeva et al. (1994) we affirm that the
see-saw pattern in the annual cycles of tropical and combined
extratropical temperatures provides an important pointer to
mechanistic models for interannual variability and trends, but
additionally conclude that
the feedback of dynamically induced ozone
variations on temperatures and the
latitudinal structure of static stability
should be included as leading order
processes in such models. |
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