Role of tidal mixing on ocean exchange through the Strait of Hormuz

We investigate the influence of tides on the exchange of water between the Arabian Gulf and the Sea of Oman through the Strait of Hormuz using a high-resolution numerical model. Two numerical simulations are contrasted, one with and one without tidal forcing. We find that tides suppress exchange through the Strait, by ∼20% in the annual mean, being largest in the summer (∼30%) and diminishing in the winter (∼13%). Tides enhance the parameterised shear-driven vertical mixing inside the Gulf and Strait, mixing warm, relatively fresh surface waters downward thus reducing the density of bottom waters flowing outwards. This reduces the lateral difference of density between Gulf and Sea of Oman and hence the exchange through the Strait. Maximum reductions occur in summer when both the vertical stratification and mixing is the largest.