EAPS

Trevor McDougall, University of New South Wales

Small-scale mixing processes, of order one meter or less in vertical extent, are weak in some sense, but they are a leading order process in the bottom half of the ocean. The smallness of these processes and the absence of radiation and phase changes in seawater, enables us to often think of density surfaces as impervious plastic sheets, but there are limitations tothis way of thinking, particularly in the deep ocean. Progress will be described in the thermodynamic understanding of ocean mixing processes. A simple volume and buoyancy budget study will be described that shows that the abyssal ocean has strong upwelling very close to the sloping side walls, with sinking in the ocean interior. These strong upward and downward flows are four and three times as strong, respectively, as the mean rate of upwelling of Bottom Water in the abyssal ocean.

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