Abstract
A model is constructed for the circulation of a combined subtropical and subpolar ocean. The model is similar to that first proposed by Parsons with the important difference that where the isopycnal separating the upper and lower layer outcrops, the Ekman flux is allowed to freely cross the outcrop fine instead of being blocked by the isopycnal.
It is shown that this completely alters the global circulation pattern. Outcropping of the cold layer still occurs but along the path described by Luyten, Pedlosky and Stommel, i.e., without an associated separated “Gulf Stream” current.
The Ekman flux across the outcrop line implies a water mass conversion which can be calculated directly from the wind stress distribution and is of the order of 5 Sverdrups. This water is allowed to return to the cold water domain along the northern rim and forms a novel branch to the classical Stommel-Arons circulation picture.
A free parameter in this model is the depth of the warm water layer, H, on the eastern boundary. However, it is shown that the requirement of continuous solutions requires H to be greater than a critical minimum value which depends only on the reduced gravity γ, the maximum wind stress, τM, and the ocean width Ξε according to the relationThe nature of the model is then reviewed when a deep upwelling from lower to upper layer is allowed.
