Critical role for mesoscale eddy diffusion in supplying oxygen to hypoxic ocean waters

Abstract

Estimates of the oceanic lateral eddy diffusion coefficient A redi vary by more than an order of magnitude, ranging from less than a few hundred m2/s to thousands of m2/s. This uncertainty has first-order implications for the intensity of oceanic hypoxia, which is poorly simulated by the current generation of Earth System Models. Using satellite-based estimate of oxygen consumption in hypoxic waters to estimate the required diffusion coefficient for these waters gives a value of order 1000 m2/s. Varying Aredi across a suite of Earth System Models yields a broadly consistent result given a thermocline diapycnal diffusion coefficient of 1 × 10-5 m2/s. Key Points Intensity of oceanic hypoxia is controlled by the lateral diffusion coefficient. Lateral diffusion coefficient is poorly constrained. A new estimate of this coefficient is made using ocean color. ©2013. American Geophysical Union. All Rights Reserved.