Chapter 2: SEA SURFACE MICROLAYER
1988). The natural variance of the wind speed, and the implied variance of
the surface patches covered with capillaries, does not occur in the laboratory
airflow. This is an important difference between the tank airflow and the
open-ocean wind pattern; it is basically because timescales of wind velocity
fluctuations in the laboratory and in the field conditions are very different
(Soloviev and
, 1998).
Finally, as summarized by Cox (2001), several processes may be at
work:
1) Convergence/divergence of orbital motions in waves disturbs the
boundary layer at the interface where fluxes are controlled by molecular
diffusion.
2) The decay of capillary wave trains accompanying rollers delivers
horizontal momentum to the water in patches corresponding to the locations
of the wave trains. This patchy driving force can induce turbulent motions of
a size corresponding to the length of the wave train.
3) Short gravity waves and capillaries dramatically increase the
momentum transferred to the ocean via increased sea surface roughness, thus
enhancing near-surface mixing.
In addition, the properties of capillary waves depend considerably on the
presence of surfactants and surface films.
2.2.5 Chemical and photochemical reactions in the sea surface
microlayer
Complex chemical, photochemical, and biological metamorphoses take
place in the ocean microlayer. Photochemical and chemical reactions rapidly
developing within the microlayer could produce a variety of feedbacks to the
biological and physical processes (Plane et al., 1997). For example, elevated
levels of highly reactive intermediate products produced in the microlayer
could represent a ‘reaction barrier’ to the transport of gases and some
chemicals across the air-sea interface. Certain photochemical reactions
destroy or produce surfactants modifying surface films; altered surface
waves from the gravity-capillary band then affect gas exchange rates. Many
other reactions occur within the microlayer, in particular those increasing or
reducing the surface concentrations of certain gases relative to their bulk
water concentrations, as well as those influencing the types and the
distributions of microlayer materials ejected to the atmosphere during bubble
bursts and delivered to the deep ocean by coalescent particles.
2.2.6 Biological and anthropogenic influences
In this book, we mainly focus on the physics of aqueous molecular
sublayers. The physics, chemistry and biology of the sea surface,
85
Schl ssel
ü
1988). The natural variance of the wind speed, and the implied variance of
the surface patches covered with capillaries, does not occur in the laboratory
airflow. This is an important difference between the tank airflow and the
open-ocean wind pattern; it is basically because timescales of wind velocity
fluctuations in the laboratory and in the field conditions are very different
(Soloviev and
, 1998).
Finally, as summarized by Cox (2001), several processes may be at
work:
1) Convergence/divergence of orbital motions in waves disturbs the
boundary layer at the interface where fluxes are controlled by molecular
diffusion.
2) The decay of capillary wave trains accompanying rollers delivers
horizontal momentum to the water in patches corresponding to the locations
of the wave trains. This patchy driving force can induce turbulent motions of
a size corresponding to the length of the wave train.
3) Short gravity waves and capillaries dramatically increase the
momentum transferred to the ocean via increased sea surface roughness, thus
enhancing near-surface mixing.
In addition, the properties of capillary waves depend considerably on the
presence of surfactants and surface films.
2.2.5 Chemical and photochemical reactions in the sea surface
microlayer
Complex chemical, photochemical, and biological metamorphoses take
place in the ocean microlayer. Photochemical and chemical reactions rapidly
developing within the microlayer could produce a variety of feedbacks to the
biological and physical processes (Plane et al., 1997). For example, elevated
levels of highly reactive intermediate products produced in the microlayer
could represent a ‘reaction barrier’ to the transport of gases and some
chemicals across the air-sea interface. Certain photochemical reactions
destroy or produce surfactants modifying surface films; altered surface
waves from the gravity-capillary band then affect gas exchange rates. Many
other reactions occur within the microlayer, in particular those increasing or
reducing the surface concentrations of certain gases relative to their bulk
water concentrations, as well as those influencing the types and the
distributions of microlayer materials ejected to the atmosphere during bubble
bursts and delivered to the deep ocean by coalescent particles.
2.2.6 Biological and anthropogenic influences
In this book, we mainly focus on the physics of aqueous molecular
sublayers. The physics, chemistry and biology of the sea surface,
85
Schl ssel
ü