Effects of ambient stratification and shelfbreak topography on offshore transport of dense water on continental shelves

Abstract

The transport of dense water offshore from an idealized coastal polynya is examined using a primitive equation numerical model. First, the prior scaling of the equilibrium density of water produced within the polynya is extended to include the effects of linear bottom slope. Next, ambient linear stratification is added. The equilibrium density is modified slightly by the density at the bottom at the initial time. Next, shelfbreak topography is included with both weak and strong ambient stratification. For the case of weak stratification, dense water carried to the shelfbreak within eddies moves rapidly downslope and is trapped near the bottom. The along‐shelf scale of the dense water cascading down the slope is set by the diameter of the dense water eddies that form along the periphery of the coastal polynya. For the case of strong stratification, dense water is carried offshore across the shelfbreak at an intermediate depth, injecting water originally within the polynya across the shelf and over the continental slope. A bottom‐trapped current flowing near the shelfbreak in the direction of coastal‐trapped wave propagation also forms. These results suggest that water formed within coastal polynyas over Arctic shelves may be capable of ventilating the continental slope regions and possibly central basins of the Arctic Ocean via eddy fluxes.