| This work attempts to express the change, induced by the introduction of stratification, of the Rossby eigen-modes of a closed basin with bottom topography, filled with a uniform fluid in the unperturbed configuration. Such a modification has been found in the output of a set of numerical experiments on the Argentine Basin and then computed analytically: stratification has been introduced in the mathematical form of a perturbation of a homogeneous fluid over a non flat bottom. It has been found that the eigen-modes lose their barotropic character and differences appear in the dynamical fields (velocity and pressure) from upper to lower layer. Moreover, the frequency of the modes changes; an analytical expression of this frequency correction as a function of stratification has been found. The impact on modal frequency of a geostrophic background flow has also been computed analytically. Some simple analytical results for an elementary geometrical setting have been determined. |
