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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 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]
Buoyancy-forced downwelling, often termed convection, is the deepening of a water parcel due to a change in the density of that parcel.Density changes in the surface ocean are primarily the result of evaporation, precipitation, heating, cooling, or the introduction and mixing of an alternate water or salinity source, such as river input or brine rejection.
If ocean currents vary with depth, waves can interact with them to drive the process known as Langmuir circulation, large eddies that stir down to depths of tens of meters. [3] [4] The second is wind-driven currents, which create layers in which there are velocity shears. When these shears reach sufficient magnitude, they can eat into ...
The langmuir (symbol: L) is a unit of exposure (or dosage) to a surface (e.g. of a crystal) and is used in ultra-high vacuum (UHV) surface physics to study the adsorption of gases. It is a practical unit, and is not dimensionally homogeneous , and so is used only in this field.
Gargett's research encompasses turbulence, [9] internal waves, [10] and the connections between mixing in the water column and biological processes. [11] Her research on turbulence levels in shallow waters [12] has identified Langmuir supercells, or large-scale Langmuir circulation, that cause extensive mixing of sediment in the coastal zone. [13]