NONLINEAR-INTERACTION BETWEEN TIDAL AND SUBINERTIAL BAROTROPIC FLOWS IN THE STRAIT-OF-GIBRALTAR

The present work establishes clear relationships of the amplitude and phase variation of the barotropic M-2 signal in the velocity of the cu rrent with the barotropic subinertial flow in the Strait of Gibraltar. The analytical procedure is applied on data from Gibraltar Experiment in order to obtain barotropic subinertial series and the amplitude an d phase variation of the M-2 signal series involves harmonic analysis, empirical orthogonal function analysis and complex demodulation. In a ddition, cross-spectral analysis has been applied to study these relat ionships, concerning which non-linear interaction between M-2 and the subinertial oscillation is proposed as the responsible physical mechan ism. An analytical solution characterizing this type of non-linear int eraction is offered in explanation of the experimental results. (C) El sevier, Paris.