One possible scenario for the demise of the low-mode internal tides is that they impinge upon continental shelves and dissipate their energy via a variety of mechanisms, including reflection at a near-critical angle. To understand this process, Drs. Nash, Kunze (UVic), and I deployed a line of 6 moored profilers for 44 days, and performed many lowered ADCP/CTD stations and XBT drops spanning the Oregon continental shelf (figure 1). Strong low-mode fluxes appear to impinge upon the area from deep-water sources, and figure 2). We aim to understand the fate of this energy, as well as a very strong and complex field of locally generated internal tide energy. With our estimates of energy flux at each site, and estimating the mixing via several methods, we hope to obtain an energy budget for the region, and thus determine the role of the continental shelves in dissipating internal-tidal energy generated in the deep ocean.

Figure 1:
Bathymetry of the Oregon continental slope (top right), near our experiment (lower), and a close-up of a mixing hotspot (upper right). Colors in lower panel indicate bottom roughness, and the symbols show our moored and dropped measurements. Tidal ellipses from TPXO.6 are shown.

Figure 2:
Bathymetery of the NE Pacific, and baroclinic M2 flux vectors from satellite (black), Princeton Ocean Model (yellow) and moorings (red).