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| Titel |
The impact of horizontal heterogeneities, cloud fraction, and liquid water path on warm cloud effective radii from CERES-like Aqua MODIS retrievals |
| VerfasserIn |
D. Painemal, P. Minnis, S. Sun-Mack |
| 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 ; 13, no. 19 ; Nr. 13, no. 19 (2013-10-11), S.9997-10003 |
| Datensatznummer |
250085743
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| Publikation (Nr.) |
 copernicus.org/acp-13-9997-2013.pdf |
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| Zusammenfassung |
| The impact of horizontal heterogeneities, liquid water path (LWP from
AMSR-E), and cloud fraction (CF) on MODIS cloud effective radius (re),
retrieved from the 2.1 μm (re2.1) and 3.8 μm
(re3.8) channels, is investigated for warm clouds over the southeast
Pacific. Values of re retrieved using the CERES algorithms are averaged
at the CERES footprint resolution (∼20 km), while heterogeneities
(Hσ) are calculated as the ratio between the standard deviation
and mean 0.64 μm reflectance. The value of re2.1 strongly
depends on CF, with magnitudes up to 5 μm larger than those for
overcast scenes, whereas re3.8 remains insensitive to CF. For cloudy
scenes, both re2.1 and re3.8 increase with Hσ for any
given AMSR-E LWP, but re2.1 changes more than for re3.8.
Additionally, re3.8–re2.1 differences are positive (<1 μm) for
homogeneous scenes (Hσ < 0.2) and LWP > 45 gm−2, and
negative (up to −4 μm) for larger Hσ. While
re3.8–re2.1 differences in homogeneous scenes are qualitatively
consistent with in situ microphysical observations over the region of study,
negative differences – particularly evinced in mean regional maps – are more
likely to reflect the dominant bias associated with cloud heterogeneities
rather than information about the cloud vertical structure. The consequences
for MODIS LWP are also discussed. |
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