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| Titel |
Bulk microphysical properties of semi-transparent cirrus from AIRS: a six year global climatology and statistical analysis in synergy with geometrical profiling data from CloudSat-CALIPSO |
| VerfasserIn |
A. Guignard, C. J. Stubenrauch, A. J. Baran, R. Armante |
| 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. 1 ; Nr. 12, no. 1 (2012-01-10), S.503-525 |
| Datensatznummer |
250010448
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| Publikation (Nr.) |
 copernicus.org/acp-12-503-2012.pdf |
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| Zusammenfassung |
| This article presents a retrieval method and a statistical analysis of the
bulk microphysical properties of semi-transparent ice clouds using the
Atmospheric Infrared Sounder (AIRS). The method relies on spectral
differences of cirrus emissivities in the 8–12 μm range and is sensitive
to the effective ice crystal diameter (De) and ice water path (IWP) of up
to 85 μm and 120 g m−2, respectively. An indication of the most
frequent ice crystal habit in the cirrus has been obtained by using
separately single scattering properties of column-like and aggregate-like ice
crystals in the simulations. Uncertainties due to hypotheses on atmospheric
parameters and ice crystal single scattering properties are discussed and the
cirrus emissivity and temperature range for the applicability of the method
are determined. To be sure that the cirrus only includes ice crystals, one
has to restrict the cloud temperature range to Tcld<230 K. On a global
scale, these semi-transparent ice clouds (cirrus) represent about 25% of all
high clouds and are mainly encountered in the midlatitudes during winter and
in the tropics, with an average De and IWP of 52 μm and 27 g m−2,
respectively. A comparison with bulk microphysical properties from the
TIROS-N Operational Vertical Sounder (TOVS) shows an agreement on global mean
values. The addition of spectral information revealed improvements at the
limits of the cirrus emissivity range. Collocated Radar-Lidar Geometrical
Profiling (GEOPROF) data have been used to study the vertical structure of
these clouds and to infer average ice water content (IWC) for cirrus with a
small vertical extent. This allowed us to compare and contrast
parameterizations of De as functions of IWC and IWP, respectively. |
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