Exchange of heat and momentum between the atmosphere and the ocean: a minimal model of decadal oscillations

A model of the large-scale interaction between the troposphere and the uppe r ocean, wind-driven circulation is formulated. Simplified parametrizations , built upon the conservation of global heat and momentum, relate the atmos pheric eddy heat and momentum fluxes to the zonally averaged oceanic and at mospheric temperatures. The formulation shows that the wind-driven circulat ion influences the winds by controlling the strength of the oceanic northwa rd heat transport, and thus the atmospheric northward heat transport and te mperature distribution. Because the ocean takes decades to adjust to change s in the winds, the coupled system equilibrates into a state which is perio dic in time, rather than steady. The period is linearly proportional to the transit time of long Rossby waves across the basin, and thus is of the ord er of decades for largescale basins.