Interdecadal variability of thermohaline circulation

Abstract

The variability of thermally driven circulation from a depth level coordinate ocean circulation model (GFDL MOM3) has been investigated. The model ocean is driven by a zonally uniform heat flux at the surface at the absence of surface wind stresses. It has been suggested that bottom geometries play important role in the variability of thermohaline circulation and different types of bottom geometries are considered. As reported in earlier studies, variability occurs over the polar ocean and is strongest in the flat bottom case and weakest in the bowl shaped bottom case. In the flat bottom case, the variability produces a temperature anomaly that circulates cyclonically over the polar ocean. When a continental slope of exponential shape is added along the northern or eastern wall, the variability is reduced significantly. A continental slope along the western wall, however, cannot weaken the variability. This suggests that the interaction between eastwards zonal flow at the surface driven by meridional temperature gradient and the boundaries near the northeastern corner of the basin is the main cause of the variability.