Relationship between drizzle rate, liquid water path and droplet concentration at the scale of a stratocumulus cloud system O. Geoffroy, J.-L. Brenguier, and I. Sandu GAME/CNRM (Météo-France, CNRS) 42, av. Gaspard Coriolis, 31057 Toulouse, France
Abstract. The recent ACE-2, EPIC and DYCOMS-II field experiments showed that the
drizzle precipitation rate of marine stratocumulus scales with the cloud
geometrical thickness or liquid water path, and the droplet concentration,
when averaged over a domain typical of a GCM grid. This feature is
replicated here with large-eddy-simulations using state-of-the-art bulk
parameterizations of precipitation formation in stratocumulus clouds. The
set of numerical simulations shows scaling relationships similar to the ones
derived from the field experiments, especially the one derived from the
DYCOMS-II data set. This result suggests that the empirical relationships
were not fortuitous and that they reflect the mean effect of cloud physical
processes. Such relationships might be more suited to GCM parameterizations
of precipitation from shallow clouds than bulk parameterizations of
autoconversion, that were initially developed for cloud resolving models.
Citation: Geoffroy, O., Brenguier, J.-L., and Sandu, I.: Relationship between drizzle rate, liquid water path and droplet concentration at the scale of a stratocumulus cloud system, Atmos. Chem. Phys., 8, 4641-4654, doi:10.5194/acp-8-4641-2008, 2008.