An interdecadal oscillation in an idealized ocean basin forced by constant heat flux

Abstract

The model is run using box geometry of size comparable to the North Atlantic and is driven by a constant, zonally uniform, surface heat flux. The meridional overturning in the model exhibits a peak to peak oscillation of 7 Sv about a mean of 15 Sv. The period is 50 years. Since the surface flux is constant, the oscillation is due to a balance between convergence in the oscillating part of the poleward heat transport and changes in local heat storage. A similar balance applies to the coupled model where changes in surface heat flux weakly oppose the oscillation. Including salinity, by adding a zonally uniform surface salt flux forcing, acts to weaken the oscillation but does not change its form. The oscillation is also found when the surface heat flux is calculated interactively, by coupling the ocean model to a zero-heat-capacity model of the atmosphere. -from Authors