Fluid Dynamics of Atlantic Meridional Overturning Circulation Stability

The Atlantic Ocean circulation is susceptible to large-scale instabilities with potentially disrupting climate and societal impacts. These instabilities are caused by the sensitivity of the zonally integrated flow, the Atlantic meridional overturning circulation (AMOC), to surface freshwater perturbations. The fluid dynamics of this stability problem is addressed here by focusing on the processes that set the pattern and amplitude of the equilibrium flow state, by identifying the feedback mechanisms responsible for the instabilities, and by connecting the resulting flow changes to variability and transition behavior. This framework is then used to explore why current Earth system models show such a diversity in simulating the present-day AMOC state, its multidecadal to multicentennial variability, and its projections under global warming.