Decoupling of the Surface and Bottom-Intensified Antarctic Slope Current in Regions of Dense Shelf Water Export

Abstract

The Antarctic Slope Current is guided by the topographic gradient of the Antarctic continental slope and creates a dynamical barrier between the continental shelf and the open ocean. The current's vertical structure varies around the continent affecting cross-slope water mass exchange with consequences for Antarctic mass loss, ventilation of the deep ocean, and carbon uptake. The Antarctic Slope Current is surface-intensified in many regions but bottom-intensified in regions of dense overflows. This study investigates the role of dense overflows in modifying the dynamics of the bottom-intensified flow using a 0.1° global ocean-sea ice model. The occurrence of bottom-intensification is tightly linked with dense overflows and bottom speeds correlate with dense overflows on interannual time scales. A lack of vertical connectivity between the bottom and surface flow, however, suggests that the along-slope bottom water flows are coincidentally co-located with the Antarctic Slope Current, rather than dynamically a part of the current.