Energy dissipation across the wave spectrum - Breaking and Dissipation of Ocean Surface Waves - page 321

wave-forecast models. The newly-found characteristics and properties of the wave-breaking
dissipation are still slow in making their way into operational forecast, but they are a con-
sistent feature of research wave models and hindcasting exercises these days, and new
perspectives of the operational modelling are also very encouraging.
Finally, the present Section 7.5 is dedicated to dissipation processes and their estimates,
which are unrelated to the breaking. These are many, but they are often disregarded because
in the presence of wave breaking their relative efficiency is small. It is not small, however,
for the swell, and without essential energy inputs and nonlinear interactions, the swell-
energy evolution is mainly driven by such dissipation processes. Two of them, which are
secondary in the presence of breaking, but primary in its absence are analysed in detail:
the production of turbulence by the mean wave-orbital motion, and the friction of surface
waves against the turbulent air. As also discussed in the section, the significance of such
dissipation processes extends far beyond the associated wave-energy loss and provides a
link between the surface waves, the ocean below and the atmosphere above. This loss may
be small, but the role of the lost energy in the upper-ocean mixing and in the dynamics of
the near-surface atmospheric boundary layer can be large.