Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 10, 2377-2391, 2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
08 Mar 2010
On the transitions in marine boundary layer cloudiness
I. Sandu1, B. Stevens1,2, and R. Pincus3 1Max Planck Institute for Meteorology, Hamburg, Germany
2University of California at Los Angeles, Los Angeles, California, USA
3University of Colorado/NOAA Earth System Research Lab, Boulder, Colorado, USA
Abstract. Satellite observations and meteorological reanalysis are used to examine the transition from unbroken sheets of stratocumulus to fields of scattered cumulus, and the processes controlling them, in four subtropical oceans. A Lagrangian analysis suggests that both the transition, defined as the temporal evolution in cloudiness, and the processes driving the transition, are quite similar among the subtropical oceans. The increase in sea surface temperature and the associated decrease in lower tropospheric stability appear to play a far more important role in cloud evolution than other factors including changes in large scale divergence and upper tropospheric humidity. During the summer months, the transitions in marine boundary layer cloudiness appear so systematically that their characteristics obtained by documenting the flow of thousands of individual air masses are well reproduced by the mean (or climatological) fields of the different data sets. This highlights interesting opportunities for future observational and modeling studies of these transitions.

Citation: Sandu, I., Stevens, B., and Pincus, R.: On the transitions in marine boundary layer cloudiness, Atmos. Chem. Phys., 10, 2377-2391,, 2010.
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