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| Titel |
Maintenance of polar stratospheric clouds in a moist stratosphere |
| VerfasserIn |
D. B. Kirk-Davidoff, J.-F. Lamarque |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 4, no. 1 ; Nr. 4, no. 1 (2008-03-31), S.69-78 |
| Datensatznummer |
250001513
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| Publikation (Nr.) |
 copernicus.org/cp-4-69-2008.pdf |
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| Zusammenfassung |
| Previous work has shown that polar stratospheric clouds (PSCs) could have
acted to substantially warm high latitude regions during past warm climates
such as the Eocene (55 Ma). Using a simple model of stratospheric water
vapor transport and polar stratospheric cloud (PSC) formation, we investigate
the dependence of PSC optical depth on tropopause temperature, cloud
microphysical parameters, stratospheric overturning, and tropospheric
methane. We show that PSC radiative effects can help slow removal of water
from the stratosphere via self-heating. However, we also show that the
ability of PSCs to have a substantial impact on climate depends strongly on
the PSC particle number density and the strength of the overturning
circulation. Thus even a large source of stratospheric water vapor (e.g.
from methane oxidation) will not result in substantial PSC radiative effects
unless PSC ice crystal number density is high compared to most current
observations, and stratospheric overturning (which modulates polar
stratospheric temperatures) is low. These results are supported by analysis
of a series of runs of the NCAR WACCM model with methane concentrations
varying up to one thousand times present levels. |
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