Abstract

Ocean mixing regulates the Global Overturning Circulation. Lack of knowledge of ocean mixing, its magnitude and spatial variation, leads to large uncertainties in our estimates of the volume, heat, freshwater, nutrient and tracer transports and, the role of the ocean in climate variability and feedbacks.

Methods presently used for estimating ocean circulation from hydrographic data will be discussed including their difficulty in elucidating mixing processes. The benefit of considering flow in a ‘contourwise’ sense will be demonstrated, including an example from the Southern Ocean.

A new method called the tracer-contour inverse method will be introduced. The tracer-contour inverse method is able to infer the general circulation and mixing from mean hydrographic data alone. The method is apparently less sensitive to error than conventional techniques and has been validated against the output of a numerical model. The method has been applied in the eastern North Atlantic and reproduces in-situ observations of mixing from the region.