THE NEAR-SURFACE LAYER OF THE OCEAN
where U 10 is the wind speed at 10 m height. Bortkovskii (1983) found that
the whitecap coverage varies with temperature (though he offered no
parameterization for its temperature dependence).
Equation (6.14) predicts that W c = 1 at U 10 = 38.7 m s
-1 . Extrapolation of
(6.14) to such high wind speed of course does not make sense. Nevertheless,
sea state photographs taken during a hurricane (Figure 6-1) show that at very
high wind speeds, the sea surface in fact becomes completely covered with
whitecaps. This suggests that a significant part of the energy transferred
from the atmosphere to the ocean in hurricanes may go to air entrainment in
breaking waves.
Sufficiently large rising bubbles by themselves induce turbulence in the
near-surface layer of the ocean. Bubbles with radius exceeding
approximately 1 mm shed unsteady vortices; the bubble trajectory also
becomes unstable, changing from rectilinear to zig-zagging (LimaOchoterena and Zenit, 2003). Which leads to collective behavior. Generally, the
bubble-induced water turbulence and the rise velocity of bubble swarms are
different from those of single bubbles, due to bubble interactions (Göz et al.,
2001). Also, the rising bubbles interact with the sea surface microlayer,
influencing its structure and dynamics. So far neither the bubble buoyancy
contribution to near-surface turbulence nor the bubble-induced turbulence
has been investigated thoroughly.
6.2 Sea Spray and Marine Aerosol Production
6.2.1 Introduction
The ocean surface layer is a source of sea spray and marine aerosols.
According to estimates given in Monin and Krasitskii (1985), about 0.3% of
the World Ocean surface is covered with breaking waves, and the total salt
flux into the atmosphere is about 10
12 kg per year.
The sea spray is an important factor in the air-sea transfer of heat,
moisture, and momentum under high wind speed conditions. The primary
marine aerosol is composed of seawater enriched with chemical compounds
as well as with bacteria and viruses. Both natural (biogenic) and
anthropogenic sources, dissolved in the near-surface layer of the ocean or as
a thin film on the ocean surface, contribute to the content of marine aerosols.
Large spray drops return to the ocean before evaporating. Smaller drops are
entrained into the turbulent flow in the marine boundary layer and, under
favorable conditions, completely evaporate producing sea salt aerosol
particles, which are effective cloud condensation nuclei. Influencing the
lifetime and albedo of clouds, sea salt aerosols can influence climate.
410
where U 10 is the wind speed at 10 m height. Bortkovskii (1983) found that
the whitecap coverage varies with temperature (though he offered no
parameterization for its temperature dependence).
Equation (6.14) predicts that W c = 1 at U 10 = 38.7 m s
-1 . Extrapolation of
(6.14) to such high wind speed of course does not make sense. Nevertheless,
sea state photographs taken during a hurricane (Figure 6-1) show that at very
high wind speeds, the sea surface in fact becomes completely covered with
whitecaps. This suggests that a significant part of the energy transferred
from the atmosphere to the ocean in hurricanes may go to air entrainment in
breaking waves.
Sufficiently large rising bubbles by themselves induce turbulence in the
near-surface layer of the ocean. Bubbles with radius exceeding
approximately 1 mm shed unsteady vortices; the bubble trajectory also
becomes unstable, changing from rectilinear to zig-zagging (LimaOchoterena and Zenit, 2003). Which leads to collective behavior. Generally, the
bubble-induced water turbulence and the rise velocity of bubble swarms are
different from those of single bubbles, due to bubble interactions (Göz et al.,
2001). Also, the rising bubbles interact with the sea surface microlayer,
influencing its structure and dynamics. So far neither the bubble buoyancy
contribution to near-surface turbulence nor the bubble-induced turbulence
has been investigated thoroughly.
6.2 Sea Spray and Marine Aerosol Production
6.2.1 Introduction
The ocean surface layer is a source of sea spray and marine aerosols.
According to estimates given in Monin and Krasitskii (1985), about 0.3% of
the World Ocean surface is covered with breaking waves, and the total salt
flux into the atmosphere is about 10
12 kg per year.
The sea spray is an important factor in the air-sea transfer of heat,
moisture, and momentum under high wind speed conditions. The primary
marine aerosol is composed of seawater enriched with chemical compounds
as well as with bacteria and viruses. Both natural (biogenic) and
anthropogenic sources, dissolved in the near-surface layer of the ocean or as
a thin film on the ocean surface, contribute to the content of marine aerosols.
Large spray drops return to the ocean before evaporating. Smaller drops are
entrained into the turbulent flow in the marine boundary layer and, under
favorable conditions, completely evaporate producing sea salt aerosol
particles, which are effective cloud condensation nuclei. Influencing the
lifetime and albedo of clouds, sea salt aerosols can influence climate.
410