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| Titel |
Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison |
| VerfasserIn |
M. C. Wyant, C. S. Bretherton, R. Wood, G. R. Carmichael, A. Clarke, J. Fast, R. George, W. I. Jr. Gustafson, C. Hannay, A. Lauer, Y. Lin, J.-J. Morcrette, J. Mulcahy, P. E. Saide, S. N. Spak, Q. Yang |
| 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. 1 ; Nr. 15, no. 1 (2015-01-09), S.153-172 |
| Datensatznummer |
250119291
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| Publikation (Nr.) |
 copernicus.org/acp-15-153-2015.pdf |
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| Zusammenfassung |
| A diverse collection of models are used to simulate the marine boundary
layer in the southeast Pacific region during the period of the
October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study
Regional Experiment) field campaign. Regional models simulate
the period continuously in boundary-forced free-running mode, while global
forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared
to extensive observations along a line at 20° S extending
westward from the South American coast. Most of the models simulate cloud
and aerosol characteristics and gradients across the region that are
recognizably similar to observations, despite the complex interaction of
processes involved in the problem, many of which are parameterized or poorly
resolved. Some models simulate the regional low cloud cover well, though
many models underestimate MBL (marine boundary layer) depth near the coast. Most models
qualitatively simulate the observed offshore gradients of SO2, sulfate
aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in
concentration between the MBL and the free troposphere. Most models also
qualitatively capture the decrease in cloud droplet number away from the
coast. However, there are large quantitative intermodel differences in both
means and gradients of these quantities. Many models are able to represent
episodic offshore increases in cloud droplet number and aerosol
concentrations associated with periods of offshore flow. Most models
underestimate CCN (at 0.1% supersaturation) in the MBL and free
troposphere. The GCMs also have difficulty simulating coastal gradients in
CCN and cloud droplet number concentration near the coast. The overall
performance of the models demonstrates their potential utility in simulating
aerosol–cloud interactions in the MBL, though quantitative estimation of
aerosol–cloud interactions and aerosol indirect effects of MBL clouds with
these models remains uncertain. |
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