Variability of Water Exchanges Through the Strait of Hormuz

The variability of the water mass exchange between the Arabian Gulf and the Indian Ocean is investigated using a high-resolution (1/36°) ocean model. We focus on the period from December 1996 to March 1998, having as reference in-situ measurements at the Strait of Hormuz. Previous studies, based on models and observations, suggested a perpetual deep outflow, mainly in the southern part of the Strait, and a variable flow in the upper layers. Our results confirm that there is a permanent core of a deep outflow in the Strait at depths greater than 40 m, characterized by high-salinity waters. In the southern part of the Strait, the net flow in the upper layers is seasonally varying, altering from net inflow during winter/spring to net outflow during summer/fall. The mean annual inflow/outflow transport through the Strait is estimated at 0.22 ± 0.01 Sv. Analysis of the daily net transport fields reveals significant variability that emphasize the importance of synoptic processes for the water mass exchange through the Strait. These processes influence the structure and intensity of the exchange flow pattern, exhibiting a 2–4 days period. It is shown that, on synoptic time scales, the flow is predominantly wind driven and barotropic. The wind plays the dominant role in determining the synoptic structure of the transport, with a 2-day lag.