Seminar: Dr. Sutanu Sarkar, UC San Diego

Internal gravity waves and turbulence at rough, underwater topography (Hosted: Alberto Scotti)

The oscillating tide over rough, underwater topography launches internal gravity waves, which propagate across long distances through non-uniform stratification, interact with oceanic currents and eddies, and reflect at boundaries before eventually dissipating. Internal waves can have large amplitude at depth, for instance order 300 m tall overturns recorded at Luzon Strait during the recent IWISE campaign, and are able to transport energy and nutrients into coastal waters as well as affect underwater submersibles and structures during their propagation. The vertical turbulent mixing that results from the breakdown of these waves, although critical to maintain the oceanic stratification and important for the prediction of oceanic flow patterns, is not adequately parameterized in operational numerical models.  We will present results from high-resolution numerical simulations of topographic internal waves. We will show that, by accurate representation of nonlinear processes operative in large-amplitude lee waves, at critical slopes and during parametric subharmonic instability, these simulations enable quantification of mixing at turbulent hot spots.