Evidence of multimodal structure of the baroclinic tide in the Strait of Gibraltar

The multimodal structure of the baroclinic tides in the Strait of Gibraltar is studied using observations and numerical simulations. Observational data and model results revealed the presence of two types of tidal internal waves generated over Camarinal Sill (CS). One propagates toward the Mediterranean and disintegrates into series of nonlinear short internal waves with amplitudes of 50 m and more. The second type, behind the first, propagates slower and has a longer wavelength. The vertical structure with both upward and downward displacements of isopycnals can be identified as a manifestation of higher baroclinic modes. Analysis of the empirical orthogonal functions of the ADCP measurements performed over CS and model time series has shown that the second baroclinic mode predominates in the second type of internal waves. Its amplitude can reach one third that of the first baroclinic mode of the leading waves of depression.