THE NEAR-SURFACE LAYER OF THE OCEAN
microbial degradation, chemical and photo chemical processes, and loss due
to absorption and adsorption onto particulates.
Under favorable physical conditions, the concentration of dissolved
organic matter is sufficient to produce surface enrichments of organic matter
even in oligotrophic waters, where biological productivity is low. Lifecycles
of neuston organisms and phytoplankton blooms also lead to the production
of the surface-active substances.
The source contribution primarily controls the chemical composition of
surface films. A variety of biological, chemical and physical processes may,
nevertheless, change composition, concentration, and spatial structure of the
surface films and thus modify physical properties of the air-sea interface.
Turbulence and diffusion, scavenging and transport by bubbles and buoyant
particles effectively spread surfactants over broad areas of the ocean surface.
At the same time, flow convergences associated with organized structures,
upwelling events, and internal waves have tendency to localize surfaceactive materials on various spatial scales, ranging from a few meters to
kilometers (Bock and Frew, 1993; Liss and Duce, 1997).
2.2 Physics of Aqueous Molecular Sublayers
The surface microlayer is subject to disturbances from near-surface
turbulence (wave breaking, shear, convection, rising bubbles, spray hitting
the sea surface, raindrops etc.) Breaking waves that entrain air and thereby
produce whitecaps are the most intense and obvious manifestation of the
turbulent disturbance. Waves may also break without entraining air and
producing whitecapping. This phenomenon is associated with the free(Banner and Phillips, 1974) or rollers (Csanady, 1990). Surface films
on the ocean significantly complicate the physics of the microlayer due
to the involvement of chemical and biological processes.
2.2.1 Convective and shear instability
Convection and wind-induced shear are important factors in the physics
of aqueous molecular sublayers. The molecular sublayers are not stationary
and continuous but intermittent in time and space. The boundary layer
processes in the near-surface layer of the ocean are altered by the presence of
the free surface (see Chapter 3).
Surface cooling and/or salinity increase due to evaporation initiate
convection in the upper layer of the ocean. Convection as a type of
hydrodynamic process has a tendency to self-organization and therefore
exhibits features of organization (Section 5.8). The absorption of solar
radiation or rainfall inhibits the convective instability.
76
surface boundary condition and is called microscale wave breaking
microbial degradation, chemical and photo chemical processes, and loss due
to absorption and adsorption onto particulates.
Under favorable physical conditions, the concentration of dissolved
organic matter is sufficient to produce surface enrichments of organic matter
even in oligotrophic waters, where biological productivity is low. Lifecycles
of neuston organisms and phytoplankton blooms also lead to the production
of the surface-active substances.
The source contribution primarily controls the chemical composition of
surface films. A variety of biological, chemical and physical processes may,
nevertheless, change composition, concentration, and spatial structure of the
surface films and thus modify physical properties of the air-sea interface.
Turbulence and diffusion, scavenging and transport by bubbles and buoyant
particles effectively spread surfactants over broad areas of the ocean surface.
At the same time, flow convergences associated with organized structures,
upwelling events, and internal waves have tendency to localize surfaceactive materials on various spatial scales, ranging from a few meters to
kilometers (Bock and Frew, 1993; Liss and Duce, 1997).
2.2 Physics of Aqueous Molecular Sublayers
The surface microlayer is subject to disturbances from near-surface
turbulence (wave breaking, shear, convection, rising bubbles, spray hitting
the sea surface, raindrops etc.) Breaking waves that entrain air and thereby
produce whitecaps are the most intense and obvious manifestation of the
turbulent disturbance. Waves may also break without entraining air and
producing whitecapping. This phenomenon is associated with the free(Banner and Phillips, 1974) or rollers (Csanady, 1990). Surface films
on the ocean significantly complicate the physics of the microlayer due
to the involvement of chemical and biological processes.
2.2.1 Convective and shear instability
Convection and wind-induced shear are important factors in the physics
of aqueous molecular sublayers. The molecular sublayers are not stationary
and continuous but intermittent in time and space. The boundary layer
processes in the near-surface layer of the ocean are altered by the presence of
the free surface (see Chapter 3).
Surface cooling and/or salinity increase due to evaporation initiate
convection in the upper layer of the ocean. Convection as a type of
hydrodynamic process has a tendency to self-organization and therefore
exhibits features of organization (Section 5.8). The absorption of solar
radiation or rainfall inhibits the convective instability.
76
surface boundary condition and is called microscale wave breaking