Diffusion Coefficients Calculated from the Mediterranean Salinity Anomaly in the North Atlantic Ocean

Vertical and horizontal austauch coefficients have been obtained from standard station data on the Mediterranean high-salinity tongue by use of a simple model including advection by a constant velocity and three-dimensional diffusion. It is shown that background effects can be reduced by applying the model to the salinity anomaly relative to a linear θ-S relationship. The analysis gives typical values for KH of 1.5 to 3×107 cm2 s−1 and for Kv of 0.3 to 0.7 cm2 s−1. It is argued that such values indicate the diffusion of potential density is not important in the main pycnocline of the North Atlantic anticyclonic gyre.