Mixing and vertical heat flux estimates in the Arctic Eurasian Basin

Abstract

This paper presents results of an analysis into the magnitude and distribution of vertical heat flux from the warm Atlantic Water core into the upper ocean over the southern Eurasian Basin of the Arctic Ocean as determined by Acoustic Doppler Current Profiles (ADCP) and Conductivity, Temperature, and Depth (CTD) casts made in 1993 and 1995. Vertical diffusivity parameterizations based on shear and buoyancy frequency squared are utilized, including one that assumes that turbulent dissipation rates associated with internal wave variance dissipation can be estimated from vertical shear and buoyancy frequency profiles [Gregg, M.C., 1989. Scaling turbulent diffusion in the thermocline. J. Geophys. Res., 94, pp. 9686–9698; D'Asaro, E.A., Morison, J.H., 1992. Internal waves and mixing in the Arctic Ocean. Deep-Sea Res., 39 (Suppl. 2), pp. S459–S484], and another based on an inverse Richardson number parameterization [Pacanowsky, R.C., Philander, S.G.H., 1981. Parameterization of vertical mixing in numerical models of tropical oceans. J. Phys. Oceanogr., 11, pp. 1443–1451]. Due to the scarcity of measurements in the Arctic, these data provide a preliminary indication as to the magnitude and spatial distribution of vertical heat flux from the warm core, below the halocline, into the upper ocean. The data suggest that vertical heat flux peaks over the continental slope region of the Eurasian Basin. It is possible that this diffusion is associated with elevated tidal forcing over the shelf break and slope regions, although our ship board ADCP records are too short to resolve tidal currents directly.