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| Titel |
Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes |
| VerfasserIn |
A. G. Feofilov, C. J. Stubenrauch, J. Delanoë |
| 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 ; 15, no. 21 ; Nr. 15, no. 21 (2015-11-09), S.12327-12344 |
| Datensatznummer |
250120145
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| Publikation (Nr.) |
 copernicus.org/acp-15-12327-2015.pdf |
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| Zusammenfassung |
| In this article, we discuss the shape of ice water content (IWC) vertical
profiles in high ice clouds and its effect on their radiative properties, both in short- and in long-wave bands (SW and LW). Based on the
analysis of collocated satellite data, we propose a minimal set of primitive
shapes (rectangular, isosceles trapezoid, lower and upper triangle), which
represents the IWC profiles sufficiently well. About 75 % of all
high-level ice clouds (P < 440 hPa) have an ice water path (IWP) smaller
than 100 g m−2, with a 10 % smaller contribution from single layer
clouds. Most IWC profiles (80 %) can be represented by a rectangular or
isosceles trapezoid shape. However, with increasing IWP, the number of lower
triangle profiles (IWC rises towards cloud base) increases, reaching up to
40 % for IWP values greater than 300 g m−2. The number of upper
triangle profiles (IWC rises towards cloud top) is in general small and
decreases with IWP, with the maximum occurrence of 15 % in cases of IWP
less than 10 g m−2. We propose a statistical classification of the IWC
shapes using IWP as a single parameter. We have estimated
the radiative effects of clouds with the same IWP and with different IWC
profile shapes for five typical atmospheric scenarios and over a broad range
of IWP, cloud height, cloud vertical extent, and effective ice crystal
diameter (De). We explain changes in outgoing LW fluxes at the top of the
atmosphere (TOA) by the cloud thermal radiance while differences in TOA SW
fluxes relate to the De vertical profile within the cloud. Absolute
differences in net TOA and surface fluxes associated with these parameterized
IWC profiles instead of assuming constant IWC profiles are in general of the
order of 1–2 W m−2: they are negligible for clouds with
IWP < 30 g m−2, but may reach 2 W m−2 for clouds with
IWP > 300 W m−2. |
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