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Figure 5.39 Total dissipation in the wave water column T a (5.73) versus measured total wind input
I a (denoted as T and I , respectively). Parameterisation (5.69) is used for integrating D a in (5.67) .
Figure is reproduced from Babanin et al. ( 2005 )
Figure 5.40 shows the total dissipation T a (5.73) plotted versus the total input I a , while
dissipation D a (5.67) was estimated on the basis of the wall-layer distribution for
dis
(5.68) as was suggested by a number of authors mentioned above. Dissipation for the
light-wind points now matches the wind input quite well, whereas the dissipation at winds
U 10 >
s is greatly underestimated.
An obvious conclusion to be drawn is that the volumetric rate of total turbulent kinetic
energy dissipation
7
.
5m
/
z 1 law (5.68) for waves generated
dis is distributed according to the
z 2 (i.e. similar to predictions of (5.69) ) for waves under stronger
winds. Since the inverse-quadratic dissipation has always been associated with wave break-
ing, such a conclusion is consistent with observations that the breaking does not occur for
waves forced by light winds of U 10
by light winds and as
s.
Finally, to provide better agreement between the dissipation and the energy input of the
strong-wind points in the top panel, the scale for H in (5.69) had to be adjusted. To obtain
the H
5-7m
/
6 H s scale in (5.69) , Terray et al. ( 1996 ) had to rely on an inferred wind-input
rate. Babanin et al. ( 2005 ) used the total wind input I a measured, and the comparisons
led to a conclusion that the constant-dissipation layer does not reach below H
=
0
.
=
0
.
4 H s .
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