How much water forms in the Southern Ocean? A maximum entropy approach to global water mass analysis.

A new water mass analysis method is developed to quantify the fraction of the interior ocean volume that was last ventilated in different parts of the surface ocean. The new method is formulated in terms of a deconvolution problem in which tracer observations are used to constrain the Green function, ?, for propagating prescribed surface tracer concentrations into interior concentrations. The deconvolution is regularized by maximizing the information entropy of ? subject to the constraints provided by observed surface and interior tracer concentrations. The new algorithm can be used to analyze combined steady and transient tracer data, and can incorporate in a straightforward way prior information about ? obtained from a dynamical circulation model. Applied to hydrographic data from the World Ocean Atlas (2005) the analysis suggests that approximately 70% of the total ocean volume below 1625 m is ventilated from the Southern Ocean.