Observation of Vertical Shear Increase on Eddies Mounting the Shelf
Abstract
The anticyclones that detach from the Loop Current migrate with a westward component and remainders of them reach the western shelf of the Gulf of Mexico. By the time these eddies approach the shelf they are up to 100 km in radius and deflecting isopycnals downward over 100 m at the 500 m level. Instrumented moorings, anchored over bottom depths of 130, 500, 2000 and 3500 m in the western Gulf of Mexico, allow the measurement of currents as these eddies drift over them. Altimetry data and vertical profiles of subinertial horizontal currents show a contrast in shear intensity and profile smoothness within these eddies. The most noticeable and recurrent feature is the increase in; both, vertical shear and irregularity of the velocity profile as eddies reach the 500 m isobaths. As the eddies drift over the 2000 and 3500 m deep moorings the observations show, in the top 500 m, a typical maximum shear of 1 m/(s·km) and a quite smooth profile, however, when mounting the shelf and circulating over 500 m bottom depth, the shear doubles and the smoothness is lost. In eddies over deep waters, the top 500 m have the maximum shear nearly coincident with the maximum velocity. The cases of Cameron (Jan., 2009) and Ekman (Mar., 2010) are shown in detail as they mount the shelf with a simultaneous shear increase and loss of smoothness.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMOS31C2048O
- Keywords:
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- 4520 Eddies and mesoscale processes;
- OCEANOGRAPHY: PHYSICALDE: 4528 Fronts and jets;
- OCEANOGRAPHY: PHYSICALDE: 4568 Turbulence;
- diffusion;
- and mixing processes;
- OCEANOGRAPHY: PHYSICALDE: 4572 Upper ocean and mixed layer processes;
- OCEANOGRAPHY: PHYSICAL