Inferring Circulation and Lateral Eddy Fluxes in the Arctic Ocean's Deep Canada Basin Using an Inverse Method

The deep waters in the Canada Basin display a complex temperature and salinity structure, the evolution of which is poorly understood. The fundamental physical processes driving changes in these deep water masses are investigated using an inverse method based on tracer conservation combined with empirical orthogonal function analysis of repeat hydrographic measurements between 2003 and 2015. Changes in tracer fields in the deep Canada Basin are found to be dominated by along-isopycnal diffusion of water properties from the margins into the central basin, with advection by the large-scale Beaufort Gyre circulation as well as localized, vertical mixing playing important secondary roles. In the Barents Sea branch of the Atlantic Water layer, centered around 1200-m depth, diffusion is shown to be nearly twice as important as advection to lateral transport. Along-isopycnal diffusivity is estimated to be similar to 300-600 m(2) s(-1). Large-scale circulation patterns and lateral advective velocities associated with the anticyclonic Beaufort Gyre are inferred, with an average speed of 0.6 cm s(-1). Below about 1500 m, along-isopycnal diffusivity is estimated to be similar to 200-400 m(2) s(-1).