On the Magnitude of Canyon-Induced Mixing

The location of mixing due to internal tides is important for both the ocean circulation as well as local biogeochemical processes. Numerous observations and modeling studies have shown that submarine canyons may be regions of enhanced internal tide-driven mixing, but there has not yet been a systematic study of all submarine canyons resolved in bathymetric datasets. Here, we parameterize the internal tide-driven dissipation from a suite of simulations and pair this with a global high-resolution, internal tide-resolving model and bathymetric dataset to estimate the internal-tide-driven dissipation that occurs in all documented submarine canyons. We find that submarine canyons dissipate a significant fraction of the incoming internal tide's energy, which is consistent with observations. When globally integrated, submarine canyons are responsible for dissipating 30.8–75.3 GW, or 3.2%–7.8% of the energy input into the M₂-frequency internal tides. This percentage of the internal tide energy that is dissipated in submarine canyons is comparable to or larger than previous calculations using extrapolations from observations of single canyons.