Abstract
This works corresponds to classes given by A. Rousseau in February 2014 in Toulouse, in the framework of the CIMI labex. The objective is to describe and question the models that are traditionaly used for large scale oceanography, whether in 2D or 3D. Starting from fundamental equations (mass and momentum conservation), it is explained how-thanks to approximations for which we provide justifications-one can build simpler models that allow a realistic numerical implementation. We particularly focus on the so-called traditional approximation that neglects part of the Coriolis force.