• ocean circulation;
  • atmospheric forcing

The response of the oceanic circulation to mesoscale atmospheric forcing is studied by comparing integrations of a global sea ice-ocean model with high-resolution European Centre for Medium-Range Weather Forecasts analysis data (0.4°) to those with the same forcing coarse grained to a resolution typically employed in climate models and atmospheric reanalyses (1.8°). It is shown that the representation of mesoscale features in atmospheric forcing fields leads to an increase in the strength of the wind-driven gyres in the North Atlantic and North Pacific regions of about 5–10% of its mean value. An increase of similar magnitude is found for the Atlantic meridional overturning circulation. From the results of this study it is argued that small-scale atmospheric phenomena such as fronts, mesoscale cyclones, and topographic jets play an important role in driving the mean oceanic circulation.