Sack Lunch Seminar (SLS)

Rebecca Walsh Dell (EAPS/WHOI) - Boundary Layers and Mixing in Abyssal
Canyons

Physical oceanographers have known for several decades the
total amount of abyssal mixing and upwelling required to
balance the deep-water formation, but are still working to
understand the mechanisms and locations—how and where it
happens. From observational studies, we know that areas of
rough topography are important and the hundreds of Grand Canyon-sized canyons that line mid-ocean ridges have particularly energetic mixing. I will present a mechanism for
creating energetic currents and mixing over rough topography,
based on diffusive bottom boundary layers. These boundary
layers have a previously unknown capacity to accelerate into
non-linear overflows for oceanographically-relevant topography
and can alter the stratification far from the boundary. Therefore,
these boundary layer processes may affect abyssal dynamics on
the basin scale.