The use of tidally induced vertical-mixing schemes in simulating the Pacific deep-ocean state

Abstract

An optimization experiment was conducted to reproduce the climatological distribution of water properties with an ocean general circulation model in which interior vertical mixing below the surface mixed layer is represented by tidally induced near- and far-field vertical-mixing schemes. Globally constant parameters in the tidally induced mixing schemes along with other physical parameters are optimally estimated based on the Green’s function method. The optimized model performs reasonably well in reproducing the deep-water properties of the Pacific Ocean, suggesting that the combination of tidally induced vertical-mixing schemes is useful in providing a reliable simulation of the deep-ocean state, consistent with both observed broad-scale hydrographic characteristics and recent knowledge of mixing. Adjustment of the parameters in the near-field mixing scheme was effective in improving simulation of the deep-ocean state. These results suggest that the adjustment of a small number of globally constant parameters in tidally induced and other mixing schemes based on recent knowledge of mixing through data assimilation may enable improvements in ocean state estimation throughout the entire water column, including the deep ocean.