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| Titel |
Cirrus cloud-temperature interactions in the tropical tropopause layer: a case study |
| VerfasserIn |
J. R. Taylor, W. J. Randel, E. J. Jensen |
| 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. 19 ; Nr. 11, no. 19 (2011-10-06), S.10085-10095 |
| Datensatznummer |
250010113
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| Publikation (Nr.) |
 copernicus.org/acp-11-10085-2011.pdf |
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| Zusammenfassung |
| Thin cirrus clouds in the Tropical Tropopause Layer (TTL) have important
ramifications for radiative transfer, stratospheric humidity, and vertical
transport. A horizontally extensive and vertically thin cirrus cloud in the
TTL was detected by the Cloud Aerosol LIDAR and Infrared Pathfinder Satellite
Observations (CALIPSO) on 27–29 January 2009 in the Tropical Eastern
Pacific region, distant from any regions of deep convection. These
observations indicate that the cloud is close to 3000 km in length along the
CALIPSO orbit track. Measurements over this three day period indicate that
the cloud event extended over a region from approximately 15° S to
10° N and 90° W to 150° W and may be one of the
most extensive cirrus events ever observed. Coincident temperature
observations from the Constellation of Observing Satellites for Meteorology,
Ionosphere, and Climate (COSMIC) suggest that the cloud formed in-situ as a
result of a cold anomaly arising from a midlatitude intrusion. The event
appears to last for up to 2 days and the temperature observations do not show
any indication of the expected infrared heating. It is hypothesized that the
cloud could be maintained by either nucleation of numerous small ice crystals
that don't sediment or by multiple localized ice nucleation events driven by
temperature variability at scales smaller than the overall cloud field,
producing small ice-crystal sizes which have sufficiently long residence
times (≈53 h) to maintain the cloud. It is possible that the
residence times are augmented by vertical motion which could also act to
offset the expected infrared heating. Further observations of similar events
will be required in order to conclusively explain this curious cloud. |
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