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| Titel |
Correlation among cirrus ice content, water vapor and temperature in the TTL as observed by CALIPSO and Aura/MLS |
| VerfasserIn |
T. Flury, D. L. Wu, W. G. Read |
| 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 ; 12, no. 2 ; Nr. 12, no. 2 (2012-01-16), S.683-691 |
| Datensatznummer |
250010523
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| Publikation (Nr.) |
 copernicus.org/acp-12-683-2012.pdf |
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| Zusammenfassung |
| Water vapor in the tropical tropopause layer (TTL) has a local radiative
cooling effect. As a source for ice in cirrus clouds, however, it can also
indirectly produce infrared heating. Using NASA A-Train satellite
measurements of CALIPSO and Aura/MLS we calculated the correlation of water
vapor, ice water content and temperature in the TTL. We find that temperature
strongly controls water vapor (correlation r=0.94) and cirrus clouds at
100 hPa (r=−0.9). Moreover we observe that the cirrus seasonal cycle is
highly (r=−0.9) anticorrelated with the water vapor variation in the TTL,
showing higher cloud occurrence during December-January-February. We further
investigate the anticorrelation on a regional scale and find that the strong
anticorrelation occurs generally in the ITCZ (Intertropical Convergence
Zone). The seasonal cycle of the cirrus ice water content is also highly
anticorrelated to water vapor (r=−0.91) and our results support the
hypothesis that the total water at 100 hPa is roughly constant. Temperature
acts as a main regulator for balancing the partition between water vapor and
cirrus clouds. Thus, to a large extent, the depleting water vapor in the TTL
during DJF is a manifestation of cirrus formation. |
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