Fine structure and microstructure characteristics across the northwest Atlantic Subtropical Front Academic Article uri icon

abstract

  • Vertical profiles of temperature, salinity, horizontal velocity, rate of dissipation of turbulent kinetic energy, and thermal variance are used to examine the parameterization of turbulent mixing associated with internal waves in an upper,ocean front. Previous attempts to quantify the rate of turbulent dissipation [e.g., Gi egg, 1989; Polzin et al., 1995] are based upon dynamical models of wave-wave interactions using the Garrett and Munk [1979] (GM) spectrum. Non-GM conditions (vertical and horizontal anisotropy, deviations iii-vertical wavenumber and frequency spectral shapes, and the presence of a background flow) may affect the character of wave interactions, altering the upwavenumber energy flux, which is equated with the rate of turbulent dissipation; Non-GM conditions in the data are documented, and revisions to the wave-wave interaction models are discussed. Additionally, the strength of wave-wave interactions is directly compared with the strength of wave-mean flow interactions. These data indicate that the dissipation rate is relatively insensitive to the presence of a background flow and anisotropic wave Conditions, in agreement with theoretical expectations based upon wave-wave interaction models and a model of wave-mean flow interaction at high background. Richardson number. These data support the findings of Polzin et al. [1995], who argue that the dissipation rate is most sensitive to variations in wave frequency.

publication date

  • June 15, 1996