Schedule May 25, 2018
Evolution & arrest of a turbulent stratified oceanic bottom BL over a slope
Andy Thompson (Caltech)

Ocean bottom boundary layers (BBLs) occur very close to the seafloor when currents flow over it, producing vertical mixing and motion affected by the shape of the terrain. These dynamics affect large-scale ocean circulation by extracting energy and momentum (movement of mass) from the currents. They also affect stratification (layering of the ocean by density) by mixing water with different temperatures and salt content, causing them to rise and sink due to buoyancy. Currents flowing over sloping terrain - such as along coasts - produce small but strong movement very close to the surface that moves up and down the slope due to Earth's rotation. This movement is produced because the seafloor does not allow momentum or buoyancy to be transferred into it. This effect is known as Ekman arrest, which changes how the density layers interact with the slope, causing them to tilt perpendicular to the sloping surface and reduce the amount of turbulence (mixing) that occurs in the BBL. This study uses a numerical model called large eddy simulation to characterize Ekman arrest and its effect on turbulence under different conditions, which could prove useful for ocean circulation models. Observations of ocean currents hugging the coast of the Antarctic Peninsula provide evidence that BBL mixing can have significant effects on the large-scale ocean circulation that is driven by buoyancy.

To download: Right-click and choose "Save Link As..."   (Other video options)

To begin viewing slides, click on the first slide below. (Or, view as pdf.)

[01] [02] [03] [04] [05] [06] [07] [08] [09] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31]

Author entry (protected)