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variability on multi-decadal timescales. Heat exchange between the ocean and the
atmosphere (heat
fluxes), atmospheric circulation and hence the effect of winds on
the ocean surface (wind stress) and a large-scale anomaly of sea surface temperature
are principal areas of investigations based on the numerous observations and
models.
Ocean-atmosphere coupling in different latitudes remains a subject of intense
research and even heated debate. Climate variability is determined to a large extent
by random atmospheric variability, also known as the atmospheric
fl
and
passive oceanic response to the atmospheric forcing. Numerous efforts to param-
eterize the ocean-atmosphere interactions within different aspects of simulation
modeling did not give some successful results. The main dif
“
noise,
”
culties arising in the
solution of tasks are caused by instability of the ocean-atmosphere system (OAS).
For this reason, Soldatov (2009a, b) proposed a new approach to the study of the
ocean-atmosphere interactions considering the state of this system as the assembly
of its phases.
There exist scales that classify the OAS states. The most known of them are
Saf
r-Simpson Hurricane scale, Beaufort scale and Fujita-Pearson scale.
Saf
r and
meteorologist Bob Simpson, who at the time was director of the U.S. National
Hurricane Center (NHC). This scale is a classi
r-Simpson scale was developed in 1971 by civil engineer Herbert Saf
cation used for some Western
Hemisphere tropical cyclones that exceed the intensities of tropical depressions and
tropical storms. The scale divides hurricanes into
five categories distinguished by
the intensities of their sustained winds. To be classi
ed as a hurricane, a tropical
cyclone must have maximum sustained winds of at least 74 mph (33 m/s; 64 kn;
119 km/h). The highest classi
cation in the scale, Category 5, is reserved for storms
with winds exceeding 155 mph (69 m/s; 135 kn; 249 km/h). Really there exist two
additional categories that correspond to storm and depression (Table
7.1
).
The Beaufort scale (Table
7.2
) is an empirical measure of describing wind speed
based mainly on observed sea conditions. The scale was created in 1806 by Sir
Francis Beaufort, an Irish-born British admiral and hydrographer. The Beaufort scale
was extended in 1946, when Forces 13
17 were added. However, Forces 13
17 were
-
-
Table 7.1 The Saffir-Simpson scale for the measure of the hurricane magnitude (Webster et al.
2005)
Hurricane category
Maximum wind
speed
Minimum atmospheric
pressure (hPa)
Storm surge
height (m)
m/s
km/h
Tropical depression
0
-
17
0
-
62
Tropical storm
18
-
32
63
-
118
One
33
43
119
153
≥
980
1.0
1.7
-
-
-
Two
43
50
154
177
979
965
1.8
2.6
-
-
-
-
Three
50
-
56
178
-
209
964
-
945
2.7
-
3.8
Four
56
67
210
249
944
920
3.9
5.6
-
-
-
-
Five
>67
>250
<920
≥
5.7
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