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| Titel |
On the interaction between marine boundary layer cellular cloudiness and surface heat fluxes |
| VerfasserIn |
J. Kazil, G. Feingold, H. Wang, T. Yamaguchi |
| 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. 1 ; Nr. 14, no. 1 (2014-01-02), S.61-79 |
| Datensatznummer |
250118243
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| Publikation (Nr.) |
 copernicus.org/acp-14-61-2014.pdf |
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| Zusammenfassung |
| The interaction between marine boundary layer cellular cloudiness and surface
fluxes of sensible and latent heat is investigated. The investigation focuses
on the non-precipitating closed-cell state and the precipitating open-cell
state at low geostrophic wind speed. The Advanced Research WRF (Weather Research and Forecasting) model is used
to conduct cloud system-resolving simulations with interactive surface fluxes
of sensible heat, latent heat, and of sea salt aerosol, and with a detailed
representation of the interaction between aerosol particles and clouds. The
mechanisms responsible for the temporal evolution and spatial distribution of
the surface heat fluxes in the closed- and open-cell state are investigated
and explained. It is found that the closed-cell state imposes its horizontal
spatial structure on surface air temperature and water vapor, and, to a
lesser degree, on the surface sensible and latent heat flux. The responsible
mechanism is the entrainment of dry, free tropospheric air into the boundary
layer. The open-cell state is associated with oscillations in surface air
temperature, water vapor, and in the surface fluxes of sensible heat, latent
heat, and of sea salt aerosol. Here, the responsible mechanism is the
periodic formation of clouds, rain, and of cold and moist pools with elevated
wind speed. Open-cell cloud formation, cloud optical depth and liquid water
path, and cloud and rain water path are identified as good predictors of the
horizontal spatial structure of surface air temperature and sensible heat
flux, but not of surface water vapor and latent heat flux. It is shown that
the open-cell state creates conditions conducive to its maintenance by
enhancing the surface sensible heat flux. The open-cell state also enhances
the sea salt flux relative to the closed-cell state. While the open-cell
state under consideration is not depleted in aerosol and is insensitive to
variations in sea salt fluxes, in aerosol-depleted conditions, the
enhancement of the sea salt flux may replenish the aerosol needed for cloud
formation and hence contribute to the maintenance of the open-cell state.
Spatial homogenization of the surface fluxes is found to have only a small
effect on cloud properties in the investigated cases. |
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