On the role of the ocean in the Atlantic Multi-decadal

13 The relative roles of the ocean and the atmosphere in driving the Atlantic Multi-decadal Os14 cillation (AMO) are investigated by isolating the AMO components forced by anomalous 15 surface heat fluxes and ocean dynamics in a fullyand partially-coupled experiments. The 16 impact of the ocean-dynamics-forced SST on air-sea interaction is disabled in the partially17 coupled experiment in order to isolate the atmosphere-forced variability. In the partially18 coupled experiment, the ocean-forced AMO component exhibits a strong multi-decadal 19 variability (25to 50-yr periods), while the atmosphere-forced component has weak multi20 decadal variability. This ocean-forced variability is imprinted on the fully-coupled surface 21 heat fluxes, which however, damp the ocean-forced SST variability inducing them, so that the 22 fully-coupled AMO multi-decadal power is only slightly stronger than that forced by the at23 mosphere alone. Our results suggest that the multi-decadal variability of the AMO is largely 24 driven by ocean dynamics, but its power is also determined by the strength air-sea coupling. 25