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Coastal upwelling is the best known type of upwelling, and the most closely related to human activities as it supports some of the most productive fisheries in the world. Coastal upwelling will occur if the wind direction is parallel to the coastline and generates wind-driven currents.
A Wind generated current is a flow in a body of water that is generated by wind friction on its surface. Wind can generate surface currents on water bodies of any size. The depth and strength of the current depend on the wind strength and duration, and on friction and viscosity losses, [1] but are limited to about 400 m depth by the mechanism, and to lesser depths where the water is shallower. [2]
Another important factor to take into account, especially when considering ocean-wind interaction, is the role played by eddy-induced Ekman pumping. [7] Some other limitations of the explanation above are due to the idealised, quasi circular linear dynamical response to perturbations that neglects the vertical displacement that a particle can ...
The wind stress curl in this region drives the Ekman suction, which creates an upwelling of nutrient-rich water from the lower depths. [ 25 ] Subpolar circulation in the southern hemisphere is dominated by the Antarctic Circumpolar Current , due to the lack of large landmasses breaking up the Southern Ocean .
Due to upwelling and downwelling, which are both wind-driven, mixing of different layers can occur through the rise of cold nutrient-rich and sinking of warm water, respectively. Generally, layers are based on water density : heavier, and hence denser, water is below the lighter water, representing a stable stratification .
The upwelling is less intense and takes place over a wider band under the divergence zone. In wind speeds ranging from 2–12 m/s (6.6–39.4 ft/s) the maximum vertical velocity ranged from 2–10 cm/s (0.79–3.94 in/s) with a ratio of down-welling to wind velocities ranging from −0.0025 to −0.0085. [8]
From an oceanographic point of view, the equatorial cold tongue is caused by easterly winds. Were the Earth climate symmetric about the equator, cross-equatorial wind would vanish, and the cold tongue would be much weaker and have a very different zonal structure than is observed today. [3] The Walker circulation was discovered by Gilbert Walker.
In fluid dynamics, a wind wave, or wind-generated water wave, is a surface wave that occurs on the free surface of bodies of water as a result of the wind blowing over the water's surface. The contact distance in the direction of the wind is known as the fetch. Waves in the oceans can travel thousands of kilometers before reaching land.