Influence of the Madagascar Ridge on Eddy Variability in the Agulhas
Current System: A Modelling Study
Abstract
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”.