Contents vii 



Page 



Forces and their Relationship to the Structure of the Ocean 312 



1. External, internal and secondary forces 312 



2. The basic hydrodynamic equations 320 



3. The continuity equation and the boundary-surface conditions 323 



4. Potential flow, the Bernoulli equation, impulse and the impulse form 



of the hydrodynamic equations 325 



5. Circulation and vorticity 329 



XI. The Ocean at Rest (Statics of the Ocean) 337 



1. The basic static equation and the conditions for static equilibrium 337 



2. Quasi-static equilibrium and its importance in the dynamic evalu- 



ation of oceanographic observations 338 



3. Disturbances and re-establishment of static equilibrium 339 



XII. The Representation of Oceanic Movements and Kinematics 342 



1 . Methods of observation and measurement of oceanographic currents 342 



2. The current field and its representation 356 



3. Special cases of current fields near land and at the boundaries of water 



masses (compensation currents) 370 



4. Divergence of the current field and the continuity equation 374 



5. The Knudsen relations 379 



XIII. General Theory of Ocean Currents in a Homogeneous Sea 382 



1. Introduction 382 



2. Steady currents in a homogeneous sea without friction 383 



3. Eddy viscosity (turbulent friction) in ocean currents 387 



4. Steady currents in a homogeneous ocean under the action of external 



forces 398 



5. Ice drift 436 



6. Inertia currents 441 



XIV. Water Bodies and Stationary Current Conditions at Boundary Surfaces 45 1 



1. Water bodies and the boundary surface between them 451 



2. Stable discontinuity surfaces 453 



3. Stable stratification of water masses 458 



4. Up-and down-gliding surfaces : pulsations of stationary vortices 469 



XV. Ocean Currents in a Non-homogeneous Ocean 476 



1. Introduction 476 



2. Relationships between current and density fields in a horizontal plane. 



The law of parallel fields 476 



3. Horizontal steady currents in a stratified ocean ' 479 



4. Ekman's theory of density currents including friction 482 



5. Oceanographic applications of Bjerknes's circulation theorem 486 



6. The "reference-level" for the conversion of the relative topography of 



the pressure surfaces into the absolute one 492 



7. Remarks about the observational material necessary for a dynamic 



computation and critical discussion of the procedure 504 



8. The determination of water transport in density currents 508 



