Modelling the seasonal cycle of the exchange flow in Bab el Mandab (Red Sea)

A minimum complexity, three-layer hydraulic model has been further developed to simulate the seasonal cycle of the exchange flow in Bab el Mandab (Red Sea). Unlike earlier versions our model incorporates a realistic channel cross-section. To a good approximation the model simulates observed fluxes through the strait and the layer depths at Hanish Sill. The model results indicate that the summertime intrusion of Gulf of Aden Intermediate Water into the Red Sea has been a robust feature of the exchange for the last 10 500 years. The modern intrusion acts as a dynamic barrier to the exchange in the upper and lower layers effectively, reducing the mean annual flux in each layer by 26% and 33% compared to model runs without the intrusion.