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In physical oceanography, Langmuir circulation consists of a series of shallow, slow, counter-rotating vortices at the ocean's surface aligned with the wind. These circulations are developed when wind blows steadily over the sea surface. Irving Langmuir discovered this phenomenon after observing windrows of seaweed in the Sargasso Sea in 1927. [1]
The CL vortex force is used to explain the generation of Langmuir circulations by an instability mechanism. The CL vortex-force mechanism was derived and studied by Sidney Leibovich and Alex D. D. Craik in the 1970s and 80s, in their studies of Langmuir circulations (discovered by Irving Langmuir in the 1930s).
Langmuir circulation develops from the wind, which, through Ekman transport, creates alternating zones of convergence and divergence at the ocean surface. In convergent zones, marked by long strips of floating debris accumulation, such as the Great Pacific Garbage Patch , coherent vortices transport surface waters to the base of the mixed layer ...
Langmuir circulation results in the occurrence of thin, visible stripes, called windrows on the surface of the ocean parallel to the direction that the wind is blowing. If the wind is blowing with more than 3 m s −1 , it can create parallel windrows alternating upwelling and downwelling about 5–300 m apart.
In the upper ocean Langmuir circulations are a special case where the turbulent structures exhibit a dominant cell size. In general it is expected that Langmuir turbulence is a global ocean phenomenon and not confined to gentle wind conditions or shallow water ways (as with most observations of Langmuir circulation). [2]
Wunsch and Ferrari (2004) [citation needed] describe the global impact of spatially inhomogeneous mixing near midocean topography: “A number of lines of evidence, none complete, suggest that the oceanic general circulation, far from being a heat engine, is almost wholly governed by the forcing of the wind field and secondarily by deep water ...
In the 1940s, when Harald Sverdrup was thinking about calculating the gross features of ocean circulation, he chose to consider exclusively the wind stress component of the forcing. As he says in his 1947 paper, in which he presented the Sverdrup relation, this is probably the more important of the two.
The Ekman layer is the layer in a fluid where the flow is the result of a balance between pressure gradient, Coriolis and turbulent drag forces.