The role of barotropic and baroclinic instabilities in the formation of mesoscale eddies around the Canary Islands

Abstract

This study analyzed the formation, evolution, and dynamics of eddies generated by barotropic and baroclinic instabilities in the waters surrounding the Canary Islands. Using the satellite altimetry database from the META product and 3D structure data on salinity, temperature, and geostrophic velocity from the ARMOR3D product, the eddies were grouped according to their core spin (anticyclonic and cyclonic) and the triggering instability (barotropic and baroclinic). The results show that barotropic anticyclonic eddies are the most abundant, long-lived, with the longest and most energetic trajectories, recording the highest amplitude, radius, and mean velocity values. Seasonal variation plays a notable role in the generation and duration of eddies, especially in baroclinic eddies, which depend on their location and proximity to the North African coastal upwelling. Analysis of the vertical structure of salinity, temperature, and geostrophic velocity shows greater coherence and stability in anticyclonic eddies, with cores located at greater depths and higher surface geostrophic velocities. Eddy Kinetic Energy spatial distribution data along eddy paths confirm the higher energy of barotropic anticyclonic eddies and suggest that mesoscale eddies are structures capable of conveying both physical and biogeochemical properties.