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| Titel |
On the relationship between responses in cloud water and precipitation to changes in aerosol |
| VerfasserIn |
Z. J. Lebo, G. Feingold |
| 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. 21 ; Nr. 14, no. 21 (2014-11-11), S.11817-11831 |
| Datensatznummer |
250119149
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| Publikation (Nr.) |
 copernicus.org/acp-14-11817-2014.pdf |
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| Zusammenfassung |
| Climate models continue to exhibit strong sensitivity to the representation
of aerosol effects on cloud reflectance and cloud amount. This paper
evaluates a proposed method to constrain modeled cloud liquid water path
(LWP) adjustments in response to changes in aerosol concentration
Na using observations of precipitation susceptibility. Recent
climate modeling has suggested a linear relationship between relative LWP
responses to relative changes in Na, i.e.,
dln LWP / dln Na, and the precipitation frequency
susceptibility Spop, which is defined as the relative change in the
probability of precipitation for a relative change in Na. Using
large-eddy simulations (LES) of marine stratocumulus and trade wind cumulus
clouds, we show that these two cloud regimes exhibit qualitatively different
relationships between λ and Spop; in stratocumulus clouds,
λ increases with Spop, while in trade wind cumulus,
λ decreases with Spop. The LES-derived relationship for
marine stratocumulus is qualitatively similar but quantitatively different
than that derived from climate model simulations of oceanic clouds aggregated
over much larger spatial scales. We explore possible reasons for variability
in these relationships, including the selected precipitation threshold and
the various definitions of precipitation susceptibility that are currently in
use. Because aerosol–cloud–precipitation interactions are inherently
small-scale processes, we recommend that when deriving the relationship
between λ and Spop, careful attention be given to the cloud
regime, the scale, and the extent of aggregation of the model output or the
observed data. |
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