The Vertical Component of Epineutral Diffusion and the Dianeutral Component of Horizontal Diffusion

Abstract

Observations of the time-mean thermohaline state of the world oceans are used to identify temperature gradients (and implied diffusive heat fluxes) both horizontally and on density surfaces. Two types of density surface are used: neutral and isopycnal, with the latter giving significantly different (and poorer) results. Along-neutral-surface (epineutral) heat fluxes are estimated to have a vertical component that is upward and strong in the upper 1500 m of the extratropical oceans, and weakly downward elsewhere. Horizontal heat diffusion has a dianeutral component with a similar pattern of strong and weak fluxes, although almost all fluxes are toward water of greater density.