Geoscience Reference
In-Depth Information
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
sqrt(
σ
Phillips
)
Figure 5.28 Breaking probability
b
T
(
f
)
(2.4)
versus saturation parameter
√
σ(
f
)
. Asterisks denote
spectral-peak points. Threshold
σ
=
0
.
035 is shown with the solid line
the re
vised
plot of th
e break
ing probability
b
T
(
)
In
Figure
5.28
,
f
(2.4)
versus
σ(
)
Phillips
instead of
√
σ(
is shown;
√
σ
Phillips
rather than
σ
Phillips
is used to provide
a qualitative analogy with
Figures 5.22
-
5.25
where spectral steepness
)
f
f
was employed.
Asterisks denote the spectral-peak values, crosses are all the other data points from the fre-
quency range
(5.30)
. Based on such a figure,
Babanin & Young
(
2005
) and
Babanin
et al.
(
2007c
) concluded that the saturation
(5.31)
-
(5.32)
is not the most suitable parameter for
wave-breaking dependences. It is not possible to draw a general dependence through the
data cloud in the figure with any degree of certainty. The saturation is the fifth moment of
the spectrum, and any variations of the spectral shape, particularly at higher frequencies,
cause large scatter of this characteristic.
As a threshold property, however, the saturation produced quite a robust value. When
verified in the spectral model (
Babanin
et al.
,
2007d
,
2010c
), the threshold was chosen as
σ(
f
)
threshold
=
0
.
035
,
(5.36)
w
ith only a few ou
tliers below this value, which is also suitable as the revised threshold
σ(
f
)
Phillips
threshold
in
Figure 5.28
.
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