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Influence of the Madagascar Ridge on Eddy Variability in the Agulhas Current System: A Modelling Study
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  • Issufo Halo,
  • Roshin Pappukutty Raj,
  • Pierrick Penven,
  • Tarron Lamont,
  • Isabelle Ansorge,
  • Johnny A. Johannessen
Issufo Halo
Department of Forestry Fisheries and the Environment

Corresponding Author:[email protected]

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Roshin Pappukutty Raj
Bjerknes Center for Climate Research, University of Bergen, Norway
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Pierrick Penven
Univ Brest, CNRS, Ifremer, IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS)
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Tarron Lamont
Oceans & Coasts Research Branch
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Isabelle Ansorge
UCT, Cape Town
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Johnny A. Johannessen
Nansen Environmental and Remote Sensing Center
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A regional ocean model was used to study the influence of the Madagascar Ridge on the circulation and eddy variability in the Agulhas Current system. In the control experiment, the model was run with a realistic bathymetry, whereas in the idealized run the bathymetry was modified by flattening Madagascar Ridge. When the Ridge was suppressed, no obvious changes were observed in the large-scale circulation. However, integrated transports revealed an excess of about 10 Sv (1 Sv = 106 m3s-1) in the recirculation of the greater Agulhas Current system. Dynamic and statistically (p < 0.05) significant changes were observed at the mesoscale variability. Composite analysis of the radial distribution of the eddy azimuthal velocity, surface height, and relative vorticity within the Ridge domain in the experiments revealed that the presence of the Madagascar Ridge determines the emergence of a secondary class of large anticyclonic eddy types in the region, the “Madagascar rings”.
18 Apr 2024Submitted to ESS Open Archive
18 Apr 2024Published in ESS Open Archive