Internal tide reflection and turbulent mixing on the continental slope

Abstract

Observations of turbulence, internal waves, and subinertial flow were made over a steep, corrugated continental slope off Virginia during May-June 1998. At semidiurnal frequencies, a convergence of low-mode, onshore energy flux is approximately balanced by a divergence of high-wavenumber offshore energy flux. This conversion occurs in a region where the continental slope is nearly critical with respect to the semidiurnal tide. It is suggested that elevated near-bottom mixing (Kp ∼ 10-3 m2 s-1) observed offshore of the supercritical continental slope arises from the reflection of a remotely generated, low-mode, M2 internal tide. Based on the observed turbulent kinetic energy dissipation rate ε, the high-wavenumber internal tide decays on time scales O(1 day . No evidence for internal lee wave generation by flow over the slope's corrugations or internal tide generation at the shelf break was found at this site. © 2004 American Meteorological Society.