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| Titel |
Stratospheric variability and trends in models used for the IPCC AR4 |
| VerfasserIn |
E. C. Cordero, P. M. de F. 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 ; 6, no. 12 ; Nr. 6, no. 12 (2006-11-29), S.5369-5380 |
| Datensatznummer |
250004191
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| Publikation (Nr.) |
 copernicus.org/acp-6-5369-2006.pdf |
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| Zusammenfassung |
| Atmosphere and ocean general circulation model (AOGCM) experiments for the
Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) are
analyzed to better understand model variability and assess the importance of
various forcing mechanisms on stratospheric trends during the 20th
century. While models represent the climatology of the stratosphere
reasonably well in comparison with NCEP reanalysis, there are biases and
large variability among models. In general, AOGCMs are cooler than NCEP
throughout the stratosphere, with the largest differences in the tropics.
Around half the AOGCMs have a top level beneath ~2 hPa and show a
significant cold bias in their upper levels (~10 hPa) compared to
NCEP, suggesting that these models may have compromised simulations near 10
hPa due to a low model top or insufficient stratospheric levels. In the
lower stratosphere (50 hPa), the temperature variability associated with
large volcanic eruptions is absent in about half of the models, and in the
models that do include volcanic aerosols, half of those significantly
overestimate the observed warming. There is general agreement on the
vertical structure of temperature trends over the last few decades,
differences between models are explained by the inclusion of different
forcing mechanisms, such as stratospheric ozone depletion and volcanic
aerosols. However, even when human and natural forcing agents are included
in the simulations, significant differences remain between observations and
model trends, particularly in the upper tropical troposphere (200 hPa–100 hPa),
where, since 1979, models show a warming trend and the observations a
cooling trend. |
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