R.W. Stewart

Abstract

The physical mechanism that causes an interdecadal oscillation in a coarse resolution sector ocean model forced by mixed boundary conditions is studied. The oscillation is characterized by large fluctuations in convective activity and air/sea heat exchange on a decadal timescale. Changes in the subsurface temperature and surface salinity are essential for the existence of the oscillation. It is shown that a large part of these variations can be explained with the hypothesis of a constant ocean velocity field. This may easily lead to the erroneous conclusion that the oscillation is mainly a “nondynamical” phenomenon. In this paper it is demonstrated that the ocean dynamics play an essential role in explaining decadal oscillations.