A simple model for the three-dimensional, thermally and wind-driven ocean circulation

Neglecting rotation, the Howard-Malkus loop oscillation is retrieved, governed by the Lorenz equations. This has the equations employed in box models, in the restricted sense where no distinction is made between the restoring time scales of the temperature and salinity fields, as a special case. Although the atmospheric circulation may be chaotic, parameter values in the ocean are such that the circulation is steady or, at most, exhibits a self-sustained oscillation. For a purely thermally forced ocean, this is always a unique state. Addition of a wind-induced horizontal circulation allows for multiple equilibria, despite the neglect of the salinity field. -from Author