Final technical rept.
OREGON STATE UNIV CORVALLIS COLL OF OCEANOGRAPHY
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Under the sponsorship of this grant a pitot tube for turbulence and eddy-correlation flux measurements from vertical profilers in the ocean was developed. The development of the pitot tube led to the first critical assessment of mixing efficiencies in the ocean. These show a variability that may be due to the form of the initial instability, once again emphasizing the need to examine the physics of the instability process leading to the turbulence. The development also led to the introduction of new scalings for turbulent dissipation rate and eddy diffusivity based on the energy-containing scales of the turbulence -- this is significant in that it does not require resolution of dissipation scales and eases the measurement requirements. Measurements in mixed layers led to the discovery of the superadiabatic surface layer during convection. The analogy between the temperature structure of the convective boundary layers of ocean and atmosphere have been elucidated. Turbulence measurements near the surface led to the communitys acknowledgement that turbulence beneath a free surface cannot be predicted by standard wall boundary layer scaling. A theory of wave-turbulence interactions was developed as an attempt to explain the physics of the conversion of wave energy to turbulence which leads to the observed enhanced turbulence in the wave zone. Measurements off northern California following local storms led to detailed observations of the decay of a near-inertial wave, from which we were able to quantify the energy loss to turbulence for the first time. Small scale conductivity measurements using a new sensor led to the first estimates of salinity variance dissipation rate. This required quantifying the role of the temperature salinity cross-spectrum to the conductivity spectrum, a factor not widely appreciated in our field.
- Physical and Dynamic Oceanography