• Bouret-Aubertot, P., J. Someria, and C. Staquet, 1995: Breaking of standing internal gravity waves through two-dimensional instabilities. J. Fluid Mech., 285 , 265301.

    • Search Google Scholar
    • Export Citation
  • Linden, P. F., 1978: The formation of banded salt finger structure. J. Geophys. Res., 83 , 29022912.

  • Mack, S. A., 1985: Two-dimensional measurements of ocean microstructure: The role of double-diffusion. J. Phys. Oceanogr., 15 , 15811604.

    • Search Google Scholar
    • Export Citation
  • Mack, S. A., 1989: Towed-chain measurements of ocean microstructure. J. Phys. Oceanogr., 19 , 11081129.

  • Merryfield, W. J., 2000: Origin of thermohaline staircases. J. Phys. Oceanogr., 30 , 10461068.

  • Schmitt, R. W., 1981: Form of the temperature-salinity relationship in the Central Water: Evidence for double-diffusive mixing. J. Phys. Oceanogr., 11 , 10151026.

    • Search Google Scholar
    • Export Citation
  • Shen, C. Y., 1995: Equilibrium salt-fingering convection. Phys. Fluids, 7 , 706717.

  • Stern, M. E., 1960: The “salt-fountain” and thermohaline convection. Tellus, 12 , 172175.

  • Stern, M. E., 1969: Collective instability of salt fingers. J. Fluid Mech., 35 , 209218.

  • Stern, M. E., T. Radko, and J. Simeonov, 2001: Salt fingers in an unbounded thermocline. J. Mar. Res., 59 (3) 355390.

  • St. Laurent, L., and R. W. Schmitt, 1999: The contribution of salt fingers to vertical mixing in the North Atlantic Tracer Release Experiment. J. Phys. Oceanogr., 29 , 14041424.

    • Search Google Scholar
    • Export Citation
  • Thorpe, S. A., 1973: Turbulence in stably stratified fluids: A review of laboratory experiments. Bound.-Layer Meteor., 5 , 95119.

  • Winters, K. B., and E. A. D'Assaro, 1994: Three dimensional instability near a critical layer. J. Fluid Mech., 272 , 255284.

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Internal Wave Overturns Produced by Salt Fingers

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  • 1 Oceanography Department, The Florida State University, Tallahassee, Florida
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Abstract

The salt finger fluxes obtained in small-domain direct numerical simulations (DNSs) are used to parameterize the fluxes in a larger domain that resolves internal gravity waves. For the case in which the molecular diffusivity ratio τ = KS/KT < 1 is not excessively small, the wave amplification and overturning in a large-domain DNS that resolves both fingers and waves agrees with the result of a parameterized model. Since such a DNS is not feasible for heat–salt (τ = 1/80), the parametric model is used for 2D spectral calculations with periodic boundary conditions. For density ratios R = 1.25 and 1.5 an initialized low-frequency internal wave amplifies because of the wave strain; the irreversible (finger) fluxes and the wave potential energy increase until the isopycnals overturn. The maximum value of heat–salt flux produced by the wave is comparable to the finger fluxes in the absence of the wave. Even larger total fluxes should occur in the subsequent turbulent overturning stage (not computed), in which the viscous dissipation should be very much larger than in the pure finger stage. Although a finite-amplitude internal wave is generated for a larger R = 2.5, the overturning effect is very weak and on a relatively small scale; these “traumata” are attributed to wave–wave interactions.

Corresponding author address: Dr. Melvin Stern, Oceanography Department, The Florida State University, Tallahassee, FL 32306-4320. Email: stern@ocean.fsu.edu

Abstract

The salt finger fluxes obtained in small-domain direct numerical simulations (DNSs) are used to parameterize the fluxes in a larger domain that resolves internal gravity waves. For the case in which the molecular diffusivity ratio τ = KS/KT < 1 is not excessively small, the wave amplification and overturning in a large-domain DNS that resolves both fingers and waves agrees with the result of a parameterized model. Since such a DNS is not feasible for heat–salt (τ = 1/80), the parametric model is used for 2D spectral calculations with periodic boundary conditions. For density ratios R = 1.25 and 1.5 an initialized low-frequency internal wave amplifies because of the wave strain; the irreversible (finger) fluxes and the wave potential energy increase until the isopycnals overturn. The maximum value of heat–salt flux produced by the wave is comparable to the finger fluxes in the absence of the wave. Even larger total fluxes should occur in the subsequent turbulent overturning stage (not computed), in which the viscous dissipation should be very much larger than in the pure finger stage. Although a finite-amplitude internal wave is generated for a larger R = 2.5, the overturning effect is very weak and on a relatively small scale; these “traumata” are attributed to wave–wave interactions.

Corresponding author address: Dr. Melvin Stern, Oceanography Department, The Florida State University, Tallahassee, FL 32306-4320. Email: stern@ocean.fsu.edu

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