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| Titel |
Impact of cirrus clouds heterogeneities on top-of-atmosphere thermal infrared radiation |
| VerfasserIn |
T. Fauchez, C. Cornet, F. Szczap, P. Dubuisson, T. Rosambert |
| 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 ; 14, no. 11 ; Nr. 14, no. 11 (2014-06-05), S.5599-5615 |
| Datensatznummer |
250118776
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| Publikation (Nr.) |
 copernicus.org/acp-14-5599-2014.pdf |
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| Zusammenfassung |
| This paper presents a study of the impact of cirrus cloud heterogeneities on
the thermal infrared brightness temperatures at the top of the atmosphere (TOA).
Realistic 3-D cirri are generated by a cloud generator based on simplified
thermodynamic and dynamic equations and on the control of invariant scale
properties. The 3-D thermal infrared radiative transfer is simulated with a
Monte Carlo model for three typical spectral bands in the infrared
atmospheric window. Comparisons of TOA brightness temperatures resulting from
1-D and 3-D radiative transfer show significant differences for optically
thick cirrus (τ > 0.3 at 532 nm) and are mainly due to the
plane-parallel approximation (PPA). At the spatial resolution of
1 km × 1 km, two principal parameters control the heterogeneity
effects on brightness temperatures: i) the optical thickness standard
deviation inside the observation pixel, ii) the brightness temperature
contrast between the top of the cirrus~and the clear-sky atmosphere.
Furthermore, we show that the difference between 1-D and 3-D brightness
temperatures increases with the zenith view angle from two to ten times
between 0° and 60° due to the tilted independent pixel
approximation (TIPA). |
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