TY - THES

T1 - Dynamics of a tidally-forced stratified shear flow on the continental slope

AU - Bluteau, Cynthia

PY - 2011

Y1 - 2011

N2 - [Truncated abstract] The energy contained in large-scale ocean flows is dissipated via small-scale turbulent motions that control the rate at which heat, momentum, chemicals, nutrients, and biological matter are stirred in the ocean. On the global scale, a large proportion of the mechanical energy contained in the ocean’s tides is converted to internal wave energy that can propagate large distances before ultimately dissipating, particularly near bottom boundaries where enhanced mixing occurs. Some of the tidal energy is also dissipated locally during the internal wave generation process, especially in areas with large topographical gradients. The overall objective of this work was to investigate the physical processes governing near-bottom turbulent mixing at a continental shelf slope site to guide the development of mixing models for ocean circulation models. This first part of this thesis presents a rigorous methodology for estimating turbulence properties, in particular, the rate of dissipation of turbulent kinetic energy, from the inertial subrange of point velocity field observations. The developed methodology takes into consideration the sampling program, the instrument’s capabilities, and the flow characteristics. Notably, the method considers both the effect of large-scale anisotropy, induced by the mean velocity shear, and density stratification on turbulence spectral properties in a systematic and robust way, making the method applicable to a vast range of environmental flows.

AB - [Truncated abstract] The energy contained in large-scale ocean flows is dissipated via small-scale turbulent motions that control the rate at which heat, momentum, chemicals, nutrients, and biological matter are stirred in the ocean. On the global scale, a large proportion of the mechanical energy contained in the ocean’s tides is converted to internal wave energy that can propagate large distances before ultimately dissipating, particularly near bottom boundaries where enhanced mixing occurs. Some of the tidal energy is also dissipated locally during the internal wave generation process, especially in areas with large topographical gradients. The overall objective of this work was to investigate the physical processes governing near-bottom turbulent mixing at a continental shelf slope site to guide the development of mixing models for ocean circulation models. This first part of this thesis presents a rigorous methodology for estimating turbulence properties, in particular, the rate of dissipation of turbulent kinetic energy, from the inertial subrange of point velocity field observations. The developed methodology takes into consideration the sampling program, the instrument’s capabilities, and the flow characteristics. Notably, the method considers both the effect of large-scale anisotropy, induced by the mean velocity shear, and density stratification on turbulence spectral properties in a systematic and robust way, making the method applicable to a vast range of environmental flows.

KW - Turbulence

KW - Internal waves

KW - Physical oceanography

KW - Oceanographic observation

KW - Australia north-west shelf

M3 - Doctoral Thesis

ER -