Generation of submesoscale frontal eddies in the Agulhas Current

Type Article
Date 2019-11
Language English
Author(s) Tedesco Pauline1, Gula Jonathan5, Ménesguen ClaireORCID1, Penven Pierrick5, Krug M.2, 3, 4
Affiliation(s) 1 : Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM Brest ,France
2 : Council for Scientific and Industrial Research, Natural Resources and the Environment Cape Town ,South Africa
3 : Department of OceanographyMa‐re Institute, University of Cape Town, South Africa
4 : Nansen‐Tutu Centre for Marine Environmental Research, Department of OceanographyUniversity of Cape Town ,South Africa
5 : Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM Brest ,France
Source Journal Of Geophysical Research-oceans (2169-9275) (American Geophysical Union (AGU)), 2019-11 , Vol. 124 , N. 11 , P. 7606-7625
DOI 10.1029/2019JC015229
WOS© Times Cited 8
Keyword(s) Submesoscale, Numerical Modelling, Barotropic Instability, Agulhas Current, Frontal Eddies
Abstract

This study addresses the dynamics of the Agulhas inshore front in the submesoscale range upstream of 26°E. Submesoscale frontal eddies are observed in the vicinity of Port Elizabeth (26°E) from satellite images and in observations collected from under‐water gliders. Using a submesoscale‐resolving numerical model (dx ~ 0.75 km) we are able to simulate similar submesoscale eddies. Barotropic instability is confirmed as the generation mechanism by a 1D linear stability analysis and an eddy kinetic energy budget. Kinetic energy is transferred from the mean flow to the eddies through the mean horizontal shear, which is a signature of barotropic instability. When the Agulhas Current is in a non‐meandering state, submesoscale eddy generation is a recurrent process which locally drives the front's variability. Along the front, the spatial variability of barotropic instability is shaped by the background strain. A large strain aligned with the frontal axis intensifies the frontal shear upstream of 28°E while a weakening of the strain allows for barotropic instability to be triggered downstream. Although an intermittent process, the barotropic instability shows a dominant period of variability comparable with the variability of the Agulhas Current and Undercurrent.

Full Text
File Pages Size Access
Publisher's official version 47 19 MB Open access
Top of the page