Representation of Surface Mixed-Layer Eddies Affects the Large-Scale Ventilation of the Global Ocean

Surface mixed-layer dynamics play a crucial role in modulating the climate as it is the oceanic layer that directly communicates with the atmosphere. The resolution of global ocean models is, however, often restricted to (Formula presented.); this is too coarse to adequately resolve mixed-layer processes, and we depend on parametrizations. One of such parametrizations is the mixed-layer eddy (MLE) parametrization. Here, we compare the performance of two MLE parametrizations [Fox-Kemper et al. (2011, https://doi.org/10.1016/j.ocemod.2010.09.002 hereon BFF11) and Bodner et al. (2023, https://doi.org/10.1175/jpo-d-21-0297.1 hereon BOD23)], and document their impact in three global ocean simulations. Upon tuning, and diagnosing submesoscale-permitting truth simulations, the MLE efficiency coefficient in BOD23 ranges between the values of 0.003–0.038, while 0.06 to 0.07 for BFF11. We find that the spatial distribution of mixed-layer depth and ventilation of the abyssal ocean, using the ideal-age tracer and Atlantic Meridional Overturning Circulation as its proxy, are sensitive to the interaction between MLE parametrizations and ocean surface boundary-layer mixing schemes.