Mechanisms of turbulent mixing in the Continental Shelf bottom boundary layer
Shaw, William J.
MetadataShow full item record
LocationNew England shelf
The bottom boundary layer is an important dynamical region of shallow water flows. In this thesis, the problem of turbulent mixing in the coastal bottom boundary layer is investigated with a unique set of field measurements of velocity and sound speed that span a significant fraction of the boundary layer obtained over a six-week long period in the late summer of 1996 on the New England shelf. The energetics of the turbulent fluctuations are investigated by testing simplified budgets for turbulent kinetic energy and scalar variance. The turbulent kinetic energy budget is locally balanced while the scalar variance budget is not, probably due to turbulent diffusion. The direct effects of stratification are consistently significant only in the outer part of the boundary layer, where the flux Richardson number is approximately equal to a critical value of 0.2. Turbulence closure is investigated in terms of non-dimensional profiles of velocity and sound speed. Close to the bottom, the results are consistent with Monin-Obukhov similarity theory, while in the outer part of the boundary layer other scales including the height of the boundary layer are important for setting the turbulent length scale.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1999
Showing items related by title, author, creator and subject.
A continental shelf bottom boundary layer model : the effects of waves, currents, and a movable bed Glenn, Scott M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1983-01)A simple model for the bottom boundary layer on the continental shelf is presented. The governing equations are developed for a stratified, turbulent Ekman layer in a combined wave and current flow over a moveable sediment ...
Development of the BASS rake acoustic current sensor : measuring velocity in the continental shelf wave bottom boundary layer Morrison, Archie T. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-06)Surface swell over the continental shelf generates a sheet of oscillatory shear flow at the base of the water column, the continental shelf wave bottom boundary layer. The short periods of surface swell sharply limit the ...
Fredericks, Janet J.; Trowbridge, John H.; Williams, Albert J. (Woods Hole Oceanographic Institution, 1998-07)Electromagnetic fluctuations and turbulent vorticity fluctuations were measured over a nine month period in the strong tidal flows of the Strait of Juan De Fuca off the coast of the Olympic Peninsula of Washington. ...