On the transition from non-linear to linear regimes in the homogeneous models of the wind-driven ocean circulation

A homogeneous model of wind-driven circulation is investigated in the dynamic regimes between moderate non-linearity and linearity. The smallness of the inertial boundary layer width, relatively to the frictional one, poses the alternative of an unrealistically low horizontal velocity of the interior together with an exaggerated depth of the motion or the impossibility to produce westward intensified flows. This discontinuity, of physical nature, between moderate non-linearity and linearity suggests that the linear regime should be regarded as quite autonomous, which cannot be derived from the non-linear by suitably lowering the width of the inertial boundary layer with respect to the frictional regime.