Remarks on the westward intensification of wind-driven ocean transport

A new reading of westward intensification is put forward by decomposing the transport stream function in the sum of a couple of symmetric and anti-symmetric terms, relatively to the mirror reflection with respect to the central longitude of a reference basin, rectangular in shape and included into a certain beta plane. The consequence of the decomposition is twofold: first, the anti-symmetric term turns out to be a strict consequence of the latitudinal dependence of Coriolis acceleration, in the sense that it disappears in a hypothetical f-plane; second, whatever the wind forcing may be, the symmetric and anti-symmetric components of the meridional transport are always parallel in the western region of the basin and anti parallel in the eastern one. As a consequence of their superposition, the meridional transport is more energetic into the western region and it gives rise to the phenomenon of westward intensification. On the other hand, the components of the meridional transport tend to compensate each other in the eastern region in accordance with the Sverdrup balance.