Localized stirring in a field of salt-fingers

• Published in: Dynamics of atmospheres and oceans Vol. 35; no. 4; pp. 327 - 350
• Main Authors: Wells, M.G, Griffiths, R.W
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.10.2002; Elsevier Science
• Subjects: Double diffusion; Earth, ocean, space; Exact sciences and technology; External geophysics; Finestructure; Marine; Other topics; Physics of the oceans; Salt-fingers; Turbulence; Salt-fingers; Turbulence; Finestructure; Double diffusion; Turbulent drift; Laboratory study; Salt finger; Buoyancy; Density gradient; Experimental study; Thickening; Concentration gradient
• ISSN: 0377-0265; 1872-6879
• DOI: 10.1016/S0377-0265(02)00050-7

In a series of laboratory experiments, a partially mixed patch was produced in thick linear concentration gradients favorable to salt-finger convection. Salt-fingers, which give rise to an up-gradient flux of buoyancy, can reduce and invert the density gradient in the initial imposed patch. This leads to overturning convection within the patch if (a) the ratio of ambient T and S gradients, R ρ = αT z / βS z , is near one; (b) the initial imposed turbulence results in a nearly well-mixed patch; and (c) the patch thickness is large enough that convective eddies are able to transport T and S faster than salt-fingers. Once overturning occurs, subsequent turbulent entrainment can lead to growth of the patch thickness. Experimental results for one-dimensional patches (layers) agree well with the theoretical prediction. This thickening is in contrast to the collapse that a partially mixed three-dimensional patch would experience due to lateral intrusion in a wide tank.