The influence of tides on the AMOC in an eddy-permitting global general circulation model

The energy budget of the global ocean circulation highlights the importance of winds and tides as primary energy sources. Tidal influence extends throughout the water column, particularly in regions of rough topography where internal waves are generated, leading to the conversion of energy from barotropic to baroclinic high-frequency modes. Our study explores the impact of tidal forcing on the general circulation using different experiments of a mesoscale-permitting global ocean model, with the addition of a topographic wave drag parametrization for unresolved scales. The focus is specifically on the Atlantic meridional overturning circulation (AMOC). Our findings reveal that tides interact with mesoscale structures, either reinforcing or weakening the mean circulation based on the dynamic conditions of the flow. On a basin scale, we find that the meridional circulation is weakened by tides on multidecadal time scales, despite robust interannual variability. We analyze these impacts in the momentum balance, concentrating on the role of tides in altering the AMOC geostrophic balance.