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sublayer is missing and is replaced by a viscous sublayer. The wave sublayer is
approximately five wave heights deep and the constant-flux sublayer depth depends
on the surface roughness, too.
At the top of unstably stratified marine boundary layers rolls and cellular con-
vection patterns can develop. Since the detection and monitoring of these cloud
features is beyond the present abilities of ground-based remote sensing, they are not
addressed further here.
Overviews of air-sea interaction, the drag forces exerted on the marine boundary
layer, and detailed discussions of momentum transfer between the sea surface and
the air above may be found in Donelan (
1990
), Banner and Peirson (
1998
), and
Foreman and Emeis (
2010
). Sullivan and McWilliams (
2010
) discuss the coupling
processes between surface gravity waves and adjacent winds and currents in the
turbulent boundary layers of the atmosphere and the ocean.
2.5.1 Land-Sea Wind System
Due to the different thermal inertia of land and sea surfaces, secondary circulation
systems - land-sea wind systems - can form at the shores of oceans and larger lakes,
which modify the ABL structure. Under clear-sky conditions and low to moderate
winds, land surfaces become cooler than the adjacent water surface due to long-
wave emittance at night and they become warmer than the water surface due to
the absorption of short-wave irradiance during daytime. As a consequence, rising
motion occurs over the warmer and sinking motion over the cooler surfaces. A flow
from the cool surface towards the warm surface develops near the surface and a
Fig. 2.9
Schematic presentation of a height cross-section of a land-sea breeze system during
daytime (
top
) and night-time (
below
)
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