Turbulent mixing near rough topography

Microstructure and velocity observations were analyzed for three distinct topographic regions: Monterey Submarine Canyon, Monterey Bay shelf, and the Kaena Ridge, Hawaii. Processes observed include: internal wave focusing (canyon), internal wave generation (canyon, shelfbreak, ridge), internal solitary-like waves (shelf), nonlinear energy transfer (ridge) and topographic steering of flow (ridge).; The observations in Monterey Canyon were the first microstructure survey near the head of a submarine canyon and confirmed earlier inferences that coastal submarine canyons were sites of intense mixing. Mixing, which was amongst the highest observed, occurred mainly in an on-axis stratified turbulent layer. As well as the predicted focusing of internal waves, our flux estimates suggest local generation within the canyon.; Observations on the Monterey Bay shelf showed what we believe to be large high-aspect-ratio downslope-propagating internal solitary-like waves of elevation (upward displacement). Upon reaching the canyon rim, these waves propagated into deep water and transformed into waves of depression (downward displacement). Over the canyon, the solitary-like waves accounted for 45% of the dissipation observed in the upper 150 m. The observed velocity field was normally dominated by upward energy propagation from a locally generated internal tide, but downward energy propagation from an offshore generated internal tide was also observed.; The Hawaiian Ridge is one of the regions of largest M 2 barotropic-to-baroclinic conversion by unit area. Although the M2 tide dominates both the barotropic currents and the barotropic-to-baroclinic conversion, the shear field above the ridge crest was dominated by near-diurnal internal waves with a frequency of 1/2 M2 (i.e., 24.84 hour period). Analysis suggests that the 1/2 M2 waves were nonlinearly coupled to the M 2 tide between 525- and 595-m depth, which corresponded to an observed M2 characteristic.; Observations over a small seamount, 34 km northwest of Oahu, showed asymmetry in the along-ridge and across-ridge directions. Comparison with horizontal kinetic energies from a 1 km resolution numerical simulation showed the across-ridge asymmetry correlated to a M2 tidal beam emanating from the northern edge of the Kaena Ridge. Whereas, the along-ridge asymmetry was likely the result of undersampling a spatially and temporally varying flow field.