The effects of shoaling internal tides on benthic exchange events and near-boundary mixing along the continental shelf

• Main Author: Pastrana, Darren L.
• Other Authors: Stanton, Timothy
• Published: Monterey, California: Naval Postgraduate School 2013
• Online Access: http://hdl.handle.net/10945/34719

Approved for public release; distribution is unlimited === The effects of shoaling inner shelf internal tidal bores and solitons on the bottom boundary layer have been observed and analyzed during October 2012 at Monterey Bay in Monterey, CA. This research utilized measurements from two different observing systems: the long range propeller-driven AUV called Daphne, and a bottom boundary layer frame measuring changes in temperature, conductivity, pressure, optics, and turbulence during a four week time period. The data collected from these platforms were used to capture the strength of the internal tides and their influence on the bottom boundary layer as they propagate and entrain sediment up into the water column. The focus of this field study, sponsored by the National Science Foundation, was to quantify turbulent intensity levels for active events near the bed and determine correlations with turbulence higher in the water column and the generation of internal nepheloid layers. Typical dissipation rate values for high turbulent events were 1e-7 m2/s3, and as a result, turbidity levels near the bed increased on average by a third. Observations show how strong changes in the water column currents, turbidity, and turbulence potentially have a large effect on divers and subsurface operating vehicles. Further research is required to provide a predictive capability of this variability.