The Atlantic Meridional Overturning Circulation (AMOC) is the Atlantic expression of a global circulation that redistributes heat, salt, and other properties throughout the World Ocean.  The Energy Exascale Earth System Model (E3SM) has a well known weak AMOC bias at low resolution (approximately 10 Sv relative to 16.9 +/- 3 Sv at the RAPID array).  To deepen our understanding of the processes that contribute to the AMOC state in E3SM, members of the "Improving Projections of AMOC and Collapse Through analysis and Simulations" project have focused on mapping out the sensitivity of the simulated AMOC to model parameters in configurations of various complexities.

An ensemble of atmospheric-forced simulations of realistic geometry demonstrates a robust model behavior in producing a weak AMOC at low resolution. Yet, a small sample of simulations illustrate the importance of tracer diffusivities in setting high-latitude stratification. In addition, we developed an idealized configuration, deemed to be the minimal complexity to represent and quantify ocean overturning transport, to map out AMOC sensitivity in an ocean of reduced complexity. Investing in lower-complexity configurations provide a framework to investigate sensitivities at lower computational cost, allowing a larger sampling of the parameter space. We aim to gradually bridge the complexity gap between these configurations to highlight the key processes underlying the E3SM behavior.