A paper describing this work has been accepted for publication in the Journal of Physical Oceanography: "Internal Tide Reflection and Turbulent Mixing on the Continental Slope", by Jonathan D. Nash, Eric Kunze, John M. Toole, and Ray W. Schmitt.
TWIST (Turbulence and Waves
over Irregular Sloping Topography)
A pdf file of Ocean Sciences 2002 Talk "Shear Intensification through Near-Critical Reflection of Low-Mode Internal Waves" (With E. Kunze, K. Polzin, J. Toole and R. Schmitt) gives an overview of this work in progress.
Movies of plane reflection from bathymetry
near the TWIST site:
As part of this analysis, simulations were
performed to observe how shear of a low-mode internal wave is intensified upon reflection by the approximate two-dimensional bathymetry
at the TWIST site. In these simulations, an upward and downward propagating
internal wave at x=0 interacts to form a standing mode in the vertical.
This wave propagates onshore and reflects from the continental slope. Topography
with a slope similar to that of the propagating rays intensifies velocity
and shear. In these simulations, N is constant, and the internal wave characteristics
have slope of 0.02. The bathymetry has been WKB-stretched; corrugations
in the along-slope direction have been ignored.
Reflection of low-mode internal waves with 2 cm/s amplitude:
CONCLUDE: Internal wave reflection is a likely source of the intense mixing observed at TWIST.
- creates a 250-m thick beam of energy flux
- >10 cm/s velocities
- high shear: Ri ~ O(1)
Movies of plane reflection from idealized
For a simplified view of wave reflection,
we show in the following simple reflection from a plane surface. From top
to bottom, the seven panels show internal waves propagating:
onshore (upward + downward)
offshore (upward + downward)
total (offshore + onshore)
Return to Jonathan Nash's homepage
The narrowest and most intense reflected
beams are associated with bottom slopes close to critical (0.02). Simulations
were performed with the following bottom slopes: