Circulation and water mass formation in the Red Sea, and the exchange with the Indian Ocean

In this dissertation work, processes involved in the circulation and water mass formation in the Red Sea and the exchange with the Indian Ocean are investigated. The study is carried out with a variety of methods, including analytical models and an Ocean General Circulation Model (the Miami Isopycnic Coordinate Ocean Model - MICOM).; First, the annual mean freshwater and heat budgets of the Red Sea are estimated, using direct observations at the strait of Bab el Mandeb. The advective salt and heat fluxes in the strait are used in the Knudsen formulation and the annual mean freshwater loss to the atmosphere is estimated at 2.06 +/- 0.22 m/year while the annual mean heat flux over the surface of the Red Sea is 11 +/- 5 Wm-2; The three-dimensional circulation in the Red Sea basin is studied analyzing the results of the MICOM simulations. The main findings of this analysis include an intensification toward the coasts, with a transition from western intensified boundary flow in the south to eastern intensified flow in the north, and a series of strong seasonal or permanent eddy-like features.; The rate of Red Sea Water (RSW) formation is also investigated with MICOM and was found to depend on the seasonal buoyancy flux. It is during winter and in the northern part of the basin that the largest amount of this water mass (about 2/3 of the final outflowing layer) is formed. The results of the simulation indicate also that the permanent cyclonic gyre in the northern end of the basin is the most probable location for the RSW formation to take place. Inside this feature the stratification becomes weaker due to doming of the isopycnals.; Finally, the variability of the exchange flow at Bab el Mandeb at synoptic time scales is examined, and a simple, linear, two-dimensional model is employed to explain the main mechanisms involved. The local wind-stress seems to be the most important forcing mechanism, which, together with changes of the atmospheric pressure inside the Red Sea basin, can explain 70% of the observed variance at synoptic time scales. (Abstract shortened by UMI.)...