Wind-driven observation and modelling in the Strait of Gibraltar

Meteorological forcing has been found to be responsible for 65% of the subtidal current variance through Gibraltar Strait. However this value does not discriminate between atmospheric pressure and wind. Conditional coherences applied to a 2-input/single output system are computed to distribute the total variance of current data from the Gibraltar Experiment into wind-only, pressure-only, noise and shared forcings. Evidence is presented which shows that, within the subtidal range, wind and atmospheric pressure force the flow equally.; This study focuses on understanding the dynamics of the wind-driven circulation in a 2-layer channel. A channel jet model proves to be very useful in explaining the dynamic balance in each of the two layers, but for relatively short time scales. To overcome this weakness, friction stresses are included, for which a steady state solution appears as an intriguing slab-flow. Numerical analysis is used to understand the dynamic processes which take place between the short time scale channel jet solution and the long-term steady state solution. The flow structure through Gibraltar Strait is shown to reach steady state in approximately one day.