Vertical Scales and Dynamics of Eddies in the Arctic Ocean’s Canada Basin

A decade of moored measurements from the Arctic Ocean’s northwestern Beaufort Gyre (collected as a component of the Beaufort Gyre Exploration Project) are analyzed to examine the range of mesoscale eddies over the water column, and the dynamical processes that set eddy vertical scales. Three classes of eddies are identified based on core depth (shallow, mid-depth and deep), with eddy vertical structure a strong function of the ambient water stratification around its core depth. Mid-depth eddies all have two distinct cores (vertically aligned and separated in depth) characterized by azimuthal velocity maxima and anomalous temperature and salinity properties. One core is located at the base of the halocline (around 200 m depth) and the other at the depth of the Atlantic Water layer (around 400 m depth). The strongly decreasing stratification in their depth range motivates a derivation for the quasi-geostrophic adjustment of a nonuniformly stratified water column to a potential vorticity anomaly. The result aids in interpreting the dynamics and origins of the double-core eddies, providing insight into heat transport across a major water mass front separating Canadian and Eurasian Water.