Instabilités barocline et paramétrique des courants de bord, application au front d'Ouessant

The first chapter of this thesis provides a detailed presentation of the motives and implications of this work, as well as a bibliographical study. Chapter two presents two preliminary analytical studies, each of them having been dealt with in earlier publications. Chapter three deals with a comprehensive study of parametrical instability in a quasi-geostrophic model, with a digital processing of non-linear developments. Lastly, chapter four assesses the possibility of parametrical instability in a concrete example. The chosen site for the realistic application is the Iroise Sea.