Chapter 2: SEA SURFACE MICROLAYER
increases with decreasing temperature and decreases with decreasing
salinity.
4) Rainfall can enhance the surface roughness as much as two orders of
magnitude by generation of impact craters, Rayleigh jets, splash
drops, and small waves (Houk and Green, 1976).
5) Raindrops falling into the ocean fragment and partly remove surface
films (Green and Houk, 1979).
6) Raindrops penetrating through the surface disturb wave motions and
damp the short gravity waves by reducing the amplitudes at which
they break (Yakimov, 1959; Manton, 1973; Tsimplis and Thorpe,
1989; Méhauté and Khangaonkar, 1990; Poon et al., 1992). As a
result, small-scale wave breaking intensifies and the surface-renewal
time period decreases.
7) Raindrops impact the sea surface and submerge into the ocean,
generating additional surface renewals.
8) Raindrops obtain horizontal momentum from the airflow at cloud
levels. These raindrops subsequently pass this momentum to the
atmospheric boundary layer and to the sea surface, adding to the
wind stress that acts on the surface (Caldwell and Elliot, 1971). All
the momentum of the drop is transferred to the ocean, as opposed to
only a small fraction of air momentum.
9) The freshwater skin coexisting with the cool skin is subject to
irreversible thermodynamic processes due to significant local
temperature and salinity gradients (Doney, 1995).
et al. (1997) made an attempt to quantify the various effects of
rain on the aqueous molecular sublayers. The irreversible thermodynamics
processes in the presence of the cool skin and freshwater skin, however,
have not yet been quantified.
2.5.1 Effects of rain on the cool skin
Following again the same approach as in Section 2.3.2, consider a fluid
element adjacent to the sea surface that participates in the process of cyclic
renewal of the surface water in the presence of rain. Initially, the fluid
element has a uniform temperature equal to the bulk-water value w
T . As it is
exposed to the interface, the molecular diffusion law governs the evolution
of the temperature difference across the thermal sublayer:
In the framework of the surface renewal theory described in Section 2.3.2
the temperature change between subsequent renewal events in the thermal
molecular sublayer of the ocean including a volume source is described by
the molecular diffusion equation similar to (2.69) but, instead of solar
radiation term, including the volume source of heat due to rain:
121
Schl ssel
ü
increases with decreasing temperature and decreases with decreasing
salinity.
4) Rainfall can enhance the surface roughness as much as two orders of
magnitude by generation of impact craters, Rayleigh jets, splash
drops, and small waves (Houk and Green, 1976).
5) Raindrops falling into the ocean fragment and partly remove surface
films (Green and Houk, 1979).
6) Raindrops penetrating through the surface disturb wave motions and
damp the short gravity waves by reducing the amplitudes at which
they break (Yakimov, 1959; Manton, 1973; Tsimplis and Thorpe,
1989; Méhauté and Khangaonkar, 1990; Poon et al., 1992). As a
result, small-scale wave breaking intensifies and the surface-renewal
time period decreases.
7) Raindrops impact the sea surface and submerge into the ocean,
generating additional surface renewals.
8) Raindrops obtain horizontal momentum from the airflow at cloud
levels. These raindrops subsequently pass this momentum to the
atmospheric boundary layer and to the sea surface, adding to the
wind stress that acts on the surface (Caldwell and Elliot, 1971). All
the momentum of the drop is transferred to the ocean, as opposed to
only a small fraction of air momentum.
9) The freshwater skin coexisting with the cool skin is subject to
irreversible thermodynamic processes due to significant local
temperature and salinity gradients (Doney, 1995).
et al. (1997) made an attempt to quantify the various effects of
rain on the aqueous molecular sublayers. The irreversible thermodynamics
processes in the presence of the cool skin and freshwater skin, however,
have not yet been quantified.
2.5.1 Effects of rain on the cool skin
Following again the same approach as in Section 2.3.2, consider a fluid
element adjacent to the sea surface that participates in the process of cyclic
renewal of the surface water in the presence of rain. Initially, the fluid
element has a uniform temperature equal to the bulk-water value w
T . As it is
exposed to the interface, the molecular diffusion law governs the evolution
of the temperature difference across the thermal sublayer:
In the framework of the surface renewal theory described in Section 2.3.2
the temperature change between subsequent renewal events in the thermal
molecular sublayer of the ocean including a volume source is described by
the molecular diffusion equation similar to (2.69) but, instead of solar
radiation term, including the volume source of heat due to rain:
121
Schl ssel
ü