HEAT-TRANSPORT BY MESOSCALE EDDIES IN AN OCEAN CIRCULATION MODEL

The role of mesoscale eddies in the poleward heat transport in the ocean is investigated; in particular, the compensation of poleward eddy heat transport by an eddy-induced mean meridional circulation is examined. A multilayer isopycnic primitive equation model of an idealized western North Atlantic is presented to test whether compensation also occurs within an isopycnic model and when the poleward eddy heat transport becomes comparable to the mean transport. Also, in this model configuration compensation of the poleward eddy heat transport arises. It is brought about by a westward eddy heat transport in the midlatitude jet, which results in a pressure drop across the basin and consequently in a modified mean meridional overturning. This compensation is discussed;within the framework of wave-mean flow interaction. It is demonstrated that compensation results from eddy-mean flow interaction when the diabatic forcing is sufficiently weak; rings are recaptured before their SST anomaly is modified significantly; When the time scale of SST anomalies is smaller than the lifetime of mesoscale rings, it is hypothesized that the non-heat transport character of eddies breaks down.