Preface
The waters of the earth are gathered in shallow, irregular,
interconnecting basins. Heated by the sun and driven by the wind,
the oceans circulate endlessly.
The general circulation of the ocean is the persistent pattern of
this flow on the scale of the basins. It is the heart and soul of physical
oceanography, and the explanation and prediction of the flow from
the principles of fluid dynamics is the chief goal of the physical
oceanographer. Along with the pattern of the motion, the associated
fields of pressure, temperature, salinity, and density are also
necessary components of a complete theory for the ocean circulation
since they are dynamically linked to the motion of the oceans.
The physical problem posed by the general circulation of the
oceans is a difficult one both experimentally and theoretically. From
the point of view of theoretical fluid mechanics the difficulty springs
fundamentally from the recirculating character of the circulation.
The fluid is gathered into a single, though highly contorted basin.
Aside from a relatively small amount of water which enters as
precipitation and leaves the ocean to enter the atmosphere due to
evaporation, the water remains in its basin and never leaves. As is
well known, the hardest problems in fluid mechanics are just those
of recirculating fluid flows since there is no location in the fluid that
can be taken as a starting point at which the properties of the flow
can be prescribed a priori. Dissipation, no matter how small, has all
the time it needs to affect the circulation in fundamental ways.
When we realize that the ocean circulation is vigorous enough that
its dynamics are also nonlinear, the difficulty becomes even more
obvious.
Nevertheless, considerable progress has been achieved in the
past 15 years in understanding the oceanic general circulation.
Problems which stubbornly defied solution for decades, such as the
theory of the thermocline, have been clarified to a considerable
degree. At the same time, problems which had been considered
"solved," such as the homogeneous model of wind-driven circulation, have displayed new and unforeseen complexities and richness
in the underlying dynamics.
The waters of the earth are gathered in shallow, irregular,
interconnecting basins. Heated by the sun and driven by the wind,
the oceans circulate endlessly.
The general circulation of the ocean is the persistent pattern of
this flow on the scale of the basins. It is the heart and soul of physical
oceanography, and the explanation and prediction of the flow from
the principles of fluid dynamics is the chief goal of the physical
oceanographer. Along with the pattern of the motion, the associated
fields of pressure, temperature, salinity, and density are also
necessary components of a complete theory for the ocean circulation
since they are dynamically linked to the motion of the oceans.
The physical problem posed by the general circulation of the
oceans is a difficult one both experimentally and theoretically. From
the point of view of theoretical fluid mechanics the difficulty springs
fundamentally from the recirculating character of the circulation.
The fluid is gathered into a single, though highly contorted basin.
Aside from a relatively small amount of water which enters as
precipitation and leaves the ocean to enter the atmosphere due to
evaporation, the water remains in its basin and never leaves. As is
well known, the hardest problems in fluid mechanics are just those
of recirculating fluid flows since there is no location in the fluid that
can be taken as a starting point at which the properties of the flow
can be prescribed a priori. Dissipation, no matter how small, has all
the time it needs to affect the circulation in fundamental ways.
When we realize that the ocean circulation is vigorous enough that
its dynamics are also nonlinear, the difficulty becomes even more
obvious.
Nevertheless, considerable progress has been achieved in the
past 15 years in understanding the oceanic general circulation.
Problems which stubbornly defied solution for decades, such as the
theory of the thermocline, have been clarified to a considerable
degree. At the same time, problems which had been considered
"solved," such as the homogeneous model of wind-driven circulation, have displayed new and unforeseen complexities and richness
in the underlying dynamics.