On the transitions in marine boundary layer cloudiness 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
Received: 02 October 2009 – Published in Atmos. Chem. Phys. Discuss.: 05 November 2009 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.
Revised: 02 February 2010 – Accepted: 26 February 2010 – Published: 08 March 2010
Citation: Sandu, I., Stevens, B., and Pincus, R.: On the transitions in marine boundary layer cloudiness, Atmos. Chem. Phys., 10, 2377-2391, doi:10.5194/acp-10-2377-2010, 2010.