Abyssal upwelling and downwelling driven by near–‐‑ boundary mixing

(McDougall, Trevor J and Ferrari, Raffaele), Journal of Physical Oceanography, vol. 47, pp. pages, 2017.

Abstract

A buoyancy and volume budget analysis of bottom-intensified mixing in the abyssal ocean reveals simple expressions for the strong upwelling in very thin continental boundary layers, and the interior near-boundary downwelling in the stratified ocean interior. For a given amount of Antarctic Bottom Water which is upwelled through neutral density surfaces in the abyssal ocean (between 2000m and 5000m) up to five times this volume flux is upwelled in narrow turbulent sloping bottom boundary layers, while up to four times the net upward volume transport of Bottom Water flows downward across isopycnals in the near-boundary stratified ocean interior. These ratios are a direct result of a buoyancy budget with respect to buoyancy surfaces, and these ratios are calculated from knowledge of the stratification in the abyss along with the assumed e-folding height that characterizes the decrease of the magnitude of the turbulent diapycnal buoyancy flux away from the sea floor. These strong diapycnal upward and downward volume transports are confined to a few hundred kilometers of the continental boundaries, with no appreciable diapycnal motion in the bulk of the interior ocean.

doi = 10.1175/JPO-D-16-0082.1

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