| Summary: | Natural variability of the Atlantic Meridional Overturning Circulation (AMOC) in a 720-year pre-industrial simulation from the coupled climate model INMCM3.0 is analyzed. In the model, AMOC has the strongest spectral maximum at a period of 15 years. On the basis of a 5-year running mean AMOC index it is shown that the transition from negative to positive AMOC phase corresponds with high water density at 35-60N and low density at 15-25N, while during the positive AMOC phase, density anomalies are weaker. A correspondence between the positive AMOC phase and positive Arctic Oscillation is identified. Positive, negative and delayed feedbacks between AMOC and surface heat and fresh water fluxes, and heat and salinity transport in the ocean are studied. The meridional oceanic fresh water flux is found to be mainly responsible for a positive feedback, while the meridional heat flux is a main factor for a delayed negative feedback for the AMOC variability.
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