The Atlantic Meridional Overturning Circulation (AMOC) is a basin-scale meridional ocean circulation system that strongly affects inter-basin redistribution of ocean heat and freshwater. Previous studies suggest that the Arctic outflow exerts a significant influence on AMOC strength via directly participating in the formation of North Atlantic Deep Water (NADW). However, the amount of Arctic outflow contributing to NADW formation, particularly its specific pathways and associated timescales, remain uncertain. To address this, we use Lagrangian trajectories of synthetic floats in a 300-year climate model to explore the characteristics of Arctic outflow entering the NADW layer at the subpolar latitudes. It is shown that in the mean state, Arctic outflow contributes approximately one-third of the subpolar AMOC on interdecadal timescales, mainly through the East Greenland Current (EGC) and recirculation within the subpolar gyre. Compared with the mean state, the contribution, pathways, and timescales of Arctic outflow are similar during the strong AMOC phase. In contrast, the Arctic outflow makes a minor contribution to the NADW during the weak AMOC phase, which predominantly occur on multidecadal timescales via recirculations in the Nordic Seas.

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