Sa. Smith et Pr. Jonas, OBSERVATIONS OF THE TURBULENT FLUXES IN FIELDS OF CUMULUS CLOUDS, Quarterly Journal of the Royal Meteorological Society, 121(526), 1995, pp. 1185-1208
Aircraft observations in fields of small maritime cumulus clouds aroun
d the British Isles have been analysed to yield kinetic energy spectra
and vertical turbulent fluxes, both within clouds and in the clear re
gions between clouds, for five cases where a cool airmass flowed over
a warmer sea surface. The flights were made at various times of the ye
ar. Profiles of the kinetic energy and turbulent fluxes have been obta
ined from observations made at several levels. It is shown that, while
the dominant source of turbulent kinetic energy may be due to evapora
tive cooling following entrainment at cloud top, in some cloud fields
production by latent heating near cloud base dominates. The location o
f the dominant energy source depends on whether the clouds penetrate t
he inversion sufficiently for instability due to cloud-top entrainment
to occur. While the resulting flux profiles observed in some of the c
ases examined here resemble those observed in stratocumulus, profiles
of similar shape are not always observed, End there are significant di
fferences between cumulus layers and stratocumulus in the magnitudes o
f the fluxes.