On the Eddy Isopycnal Thickness Diffusivity of the Gent-McWilliams Subgrid Mixing ParameterizationOutput of an eddy-resolving model of the North Atlantic Ocean is used to diagnose the eddy thickness diffusivity coefficient, K, defined by Gent and McWilliams (1990) in their quasi-adiabatic parameterization for transports by mesoscale eddies.