Ocean dynamics
Ocean dynamics define and describe the
Ocean dynamics has traditionally been investigated by sampling from instruments in situ.[1]
The
The upper ocean, characterized by warm temperatures and active motion, varies in depth from 100 m or less in the tropics and eastern oceans to in excess of 800 meters in the western subtropical oceans. This layer exchanges properties such as heat and freshwater with the atmosphere on timescales of a few years. Below the mixed layer the upper ocean is generally governed by the hydrostatic and
The deep ocean is both cold and dark with generally weak velocities (although limited areas of the deep ocean are known to have significant recirculations). The deep ocean is supplied with water from the upper ocean in only a few limited geographical regions: the subpolar
Primitive equations
Ocean dynamics are governed by
- the zonal momentum equation:
- the meridional momentum equation:
- the vertical momentum equation (assumes the ocean is in hydrostatic balance):
- the incompressible):
- the temperature equation:[2]
- the salinity equation:[2]
Here "u" is zonal velocity, "v" is meridional velocity, "w" is vertical velocity, "p" is pressure, "ρ" is density, "T" is temperature, "S" is salinity, "g" is acceleration due to gravity, "τ" is wind stress, and "f" is the Coriolis parameter. "Q" is the heat input to the ocean, while "P-E" is the freshwater input to the ocean.
Mixed layer dynamics
Mixed layer dynamics are quite complicated; however, in some regions some simplifications are possible. The wind-driven horizontal transport in the mixed layer is approximately described by
Upper ocean dynamics
Horizontal convergences and divergences within the mixed layer due, for example, to Ekman transport convergence imposes a requirement that ocean below the mixed layer must move fluid particles vertically. But one of the implications of the geostrophic relationship is that the magnitude of horizontal motion must greatly exceed the magnitude of vertical motion. Thus the weak vertical velocities associated with Ekman transport convergence (measured in meters per day) cause horizontal motion with speeds of 10 centimeters per second or more. The mathematical relationship between vertical and horizontal velocities can be derived by expressing the idea of conservation of
References
- hdl:2060/19840019194– via NASA Technical Reports Server.
- ^ WP:RS)
- ^ a b Pickard, G.L. and W.J. Emery, 1990: Descriptive Physical Oceanography, Fifth Edition. Butterworth-Heinemann, 320 pp.