When an eddy encounters shelf-slope topography

Advisor: Ken Brink (WHOI)

I studied the interaction of eddies with continental shelf-slope topography. I used the ROMS ocean model to simulate the interaction after distilling the elements of the problem down to an idealized setup.

The following video shows the evolution of a passive tracer initialized to the initial latitude location of a water parcel. The coast is at the southern boundary; and horizontal lines are isobaths. The time series is the cross-shelfbreak flux of shelf-water (defined as water parcels starting on the shelf at t = 0.)

The formation of stacked cyclones

As seen in the video, the interaction clearly results in the formation of smaller-scale secondary vortices. We term these ’stacked’ vortices to reflect their (unexpected) vertical structure wherein shelf-slope water is stacked over eddy water.

Figure 1: This sequence of images illustrates their formation. Eddy water parcels are tagged by red dye, and shelf water parcels are tagged by blue dye. A major implication is that the shelf water export is permanent, the shelf water parcels being trapped in these cyclones.

Shelf flow field forced by eddies

Figure 2: I studied the shelf flow field forced by such eddies, yielding the following schematic.