Fundamental Equations and Their Simplification

Abstract

Dynamical processes in shallow seas and over continental shelves differ markedly from those in the deep ocean for several reasons. The horizontal scales of motion are much smaller and the presence of coasts is a strong constraining influence in most locations. The depths involved are only of the order of 100 m, so that surface effects such as wind stress or surface cooling or heating extend to a large fraction of the water column, sometimes to all of it, whereas in the deep ocean the same influences reach what amounts to only a thin skin at the surface. At the same time, basins or continental shelves with characteristic horizontal dimensions of the order of 100 km behave in an ‘oceanic’ manner in the sense that motions in them are strongly affected by the Earth’s rotation. Seas of this size and larger, with depth ranges of up to a few hundred meters will be taken to constitute the coastal ocean. This defmition includes enclosed shallow seas such as the North American Great Lakes, open seas such as the broad and flat continental shelves of ‘Atlantic’ type, or the narrow and steep shelves of ‘Pacific’ type, as well as semi-enclosed bodies of water such as the Gulf of Maine or the North Sea.