Tracking eddies in a regional model of the "Cape Basin" off South Africa

• Main Authors: A. M. Doglioli, B. Blanke, S. Speich, G. Lapeyre
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Oceanic eddies; regional modeling; Agulhas Current system; South- east Atlantic Ocean; wavelets; Lagrangian diagnostics; Indian; Southern Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.60.1126; http://www.lmd.ens.fr/glapeyre/papers/Doglioli_et_al.pdf

The main goal of our study is to propose objective and quantitative tools to better evaluate the net mass exchanges across the "Cape Basin Cauldron" between the Southern Ocean, the South Atlantic and the Indian Basin. Our work is done in a regional ocean model that accounts for eddy displacements within this region where mesoscale eddies are an important means of transporting and distributing temperature and salt. Our wavelet analysis identifies objectively three-dimensional coherent structures in a simulation with resolution. Furthermore, it enables to track eddy trajectories and time evolution of eddy properties. Mass transports are calculated from the knowledge of instantaneous values of eddy volume, diameter and drift velocity. Numerical Lagrangian computations coupled with the wavelet-based definition of each eddy allow the diagnostic of the origins and fates of the water masses brought into play. Our preliminary results shed light on the dynamical and thermodynamical behavior of modeled cyclones and anticyclones. For both types of structures, we find waters originating in the South Atlantic and the Indian Ocean. We interpret the di#erences between cyclones and anticyclones mostly in terms of contrasts in the proportion of the two geographical origins and in remote water mass properties. Keywords: Oceanic eddies, regional modeling, Agulhas Current system, Southeast Atlantic Ocean, wavelets, Lagrangian diagnostics. 1.