Salt fingering

Salt fingering

Salt fingering is a mixing process that occurs when warm salty water overlies cold fresh water. It is driven by the fact that the molecular diffusion coefficient for salt is much smaller than that for heat. A small parcel of warm, salty water moving downwards into a cold fresh region will thus lose its heat before losing its salt, thus becoming denser than the water around it and sinking further. Likewise a small parcel of cold fresh water displaced upwards will gain heat by diffusion from the surrounding waters, which will then make it lighter than the surrounding waters, and cause it to rise further. Thus the fact that salinity diffuses much less efficiently than temperature paradoxically results in a turbulent process that mixes salinity much more efficiently than temperature.

Salt fingering was first described mathematically by Prof. Melvin Stern of Florida State University in 1960 and important field measurements of the process have been made by Raymond Schmitt of the Woods Hole Oceanographic Institution and Mike Gregg and Eric Kunze of the University of Washington, Seattle. A particularly interesting area for salt fingering is found in the Caribbean Sea, where it is responsible for producing a "staircase" of well-mixed layers a few meters in thickness that extend for hundreds of kilometers.

A classic paper by the American oceanographer Henry Stommel (actually predating the work of Stern) discussed the creation of a large-scale salt finger in which a column of water would be surrounded by a membrane that would allow diffusion of temperature, but not salinity. Once primed by moving cold fresher intermediate upwards, such a "perpetual salt fountain" would be able to draw energy from the local ocean stratification.

References

Gregg, M.C., (1988). Mixing in the thermohaline staircase east of Barbados. In Small Scale Turbulence and Mixing in the Ocean, eds. J.C.J. Nihoul and B.M. Jamart, Elsevier Oceanograohy Ser., 46, 453-470.

Kunze, Eric, (1987). Limits on growing, finite–length salt fingers: A Richrdson number constraint. Journal of Marine Research., 45, 533-556.

Schmitt, Raymond W. The Ocean's Salt Fingers. Scientific American, May 1995, pp. 70-75.

Stern, Melvin E., (1960). The ”salt-fountain” and thermohaline convection. Tellus, 12,172-175.

Stommel, H., Arons, A.B., & Blanchard, D. (1956). An oceanographic curiosity: theperpetual salt fountain. Deep-Sea Research, 3,152-153.

Links

http://www.planetwater.ca/research/oceanmixing/saltfingers.html


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Rayleigh–Taylor instability — The Rayleigh–Taylor instability, or RT instability (after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities, which occurs when the lighter fluid is pushing the heavier fluid. [citation… …   Wikipedia

  • Halocline — In oceanography, a halocline is a strong, vertical salinity gradient. Because salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification. Increasing salinity by one kg/m3 results in… …   Wikipedia

  • Buoyancy — The forces at work in buoyancy In physics, buoyancy (  / …   Wikipedia

  • Melvin Stern — is a U.S. academic oceanographer who focuses on fluid dynamics. He serves as the Ekman Professor of Oceanography at Florida State University and is an elected member of both the National Academy of Sciences and the American Academy of Arts… …   Wikipedia

  • Inestabilidad Rayleigh-Taylor — Evidencia de IRT en la nebulosa del Cangrejo. Simulación …   Wikipedia Español

  • Guitar tunings — Guitar standard tuning, shown one octave higher than actual pitch. (E2.A2.D3.G3.B3.e4) Guitar tunings almost always refers to the pitch of the open ( unfretted ) string, though some tunings may only realistically be attained by the use of a capo… …   Wikipedia

  • Nuclear program of Iran — See also: Iran and weapons of mass destruction Nuclear program of Iran …   Wikipedia

  • arts, East Asian — Introduction       music and visual and performing arts of China, Korea, and Japan. The literatures of these countries are covered in the articles Chinese literature, Korean literature, and Japanese literature.       Some studies of East Asia… …   Universalium

  • Khalid Sheikh Mohammed — Arabic: خالد شيخ محمد‎ Born March 1, 1964 (1964 03 01) (age 47)[ …   Wikipedia

  • Iran and weapons of mass destruction — This article is about Iran and weapons of mass destruction. For Iran s nuclear power program, see Nuclear program of Iran. Weapons of mass destruction …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”