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The ocean has entranced mankind for as long as we have gazed upon it, traversed it, dived into it, and studied it. It remains ever changing and seemingly never changing. Each wave that progresses through the. imme diate surf zone on every coast is strikingly different, yet the waves come again and again, as if never to end. The seasons come with essential reg ularity, and· yet each is individual-whatever did happen to that year of the normal rainfall or tidal behavior? This fascination with the currents of the ocean has always had a most immediate practical aspect: shipping, transportation, commerce, and war have depended upon our knowledge, when we had it, and floundered on our surprising ignorance more often than we wish to reflect. These important practical issues have commanded attention from commercial, academic, and military research scientists and engineers from the earliest era of organized scientific investigation. The matter of direct and insistent investigation was from the outset the behavior of ocean currents with long time scales; namely, those varying on annual or at least seasonal cycles. Planning for all the named enterprises depended, as they still do, of course, on the ability to predict with some certainty this class of phenomena. That ability, as with most physical sci ence, is predicated on a firm basis of observational fact to establish what, amorig the myriad of mathematical possibilities, is chosen by Nature as her expression of fact.
Sommario
The Observational Basis for Large Scale Circulation.- 1. Introduction.- 2. Surface Circulation.- 3. The Subtropical Gyres and Western Boundary Currents.- 4. Deep Circulation.- Thermocline Theories.- 1. Introduction.- 2. Formulation.- 3. Conservation Principles.- 4. Scaling and the Governing Partial Differential Equation.- 5. The Search for Similarity Solutions.- 6. Ideal Fluid Solutions of Welander.- 7. Layered Models.- Inverse Methods for Ocean Circulation.- 1. Introduction.- 2. The Physical Problem.- 3. Treatment of the Data.- 4. An Empirical Search.- 5. The Inverse Problem.- 6. Results of Inverse Calculations.- 7. Concluding Remarks.- Baroclinic Theories of the Wind Driven Circulation.- Abstract.- 1. Scale Analysis of the Equations of Motion.- 2. The Two Layer Model.- 3. The Geometry of Geostrophic Contours.- 4. The Eddy Flux of Passive Scalar and Potential Vorticity.- 5. Homogenization of Tracer Inside Closed Streamlines.- Single Layer Models of the General Circulation.- 1.1 Introduction.- 1.2 From the Sphere to the Beta Plane.- 1.3 Linear Models.- 1.4 Quasigeostrophy.- 1.5 Ekman Layers.- 1.6 The Quasigeostrophic Potential Vorticity Equation.- 1.7 Layered Models.- 2.1 The Sverdrup Balance.- 2.2 The Stommel Problem.- 2.3 The Munk Problem.- 2.4 Comparison with Observations.- 2.5 Nonlinear Perturbation of the Linear Problem.- 2.6 Free Nonlinear Solutions and Inertial Boundary Layers.- 2.7 The Nonlinear Stommel Problem.- 2.8 The Nonlinear Munk Problem.- 2.9 Abyssal Circulation.- 2.10 Effects of Relief.- 3.1 Impulsively Started Midlatitude Flow.- 3.2 Rossby Waves in a Rectangular Midlatitude Basin.- 3.3 The Midlatitude Initial Value Problem.- 3.4 The Relationship Between Transient and Steady Midlatitude Flows.- 3.5 Free Waves in the Tropics.- 3.6 The Tropical Initial Value Problem.- 3.7 The Relationship Between Transient and Steady Tropical Flows.
