Tracking coherent structures in a regional ocean model with wavelet analysis: Application to Cape Basin eddies

Abstract

This study is mainly aimed at proposing objective tools for the identification and tracking of three‐dimensional eddy structures. It is conducted with a high‐resolution numerical model of the ocean region around South Africa, and emphasis is put on Cape Basin anticyclones and cyclones thought to be actively implicated in the Indian‐Atlantic interocean exchange. We settle on wavelet analysis for the decomposition and processing of successive maps of relative vorticity for a simulation run with ° resolution. The identification of three‐dimensional coherent structures comes with the calculation of eddy trajectories and the time evolution of eddy properties. Instantaneous mass transport and momentum of eddies are calculated from the knowledge of instantaneous drift velocities, volumes, and diameters. The success of the regional model and of the analysis technique is assessed through comparisons with equivalent observations.