2026-08-27 All-Hands Presentation Meeting Notes

Abstract: The Atlantic Meridional Overturning Circulation (AMOC) is expected to weaken under continued greenhouse forcing, but models disagree on the magnitude, timing, and reversibility of this response. Assessing AMOC stability requires understanding how overturning variability is related to changes in ocean temperature and freshwater transport, and assess whether these relationships are consistent across datasets and model resolutions. We do so focusing on how ocean models represent AMOC, and we compare four ocean reanalyses and a suite of forced ocean-sea-ice simulations from three model families, each available at coarse and mesoscale-permitting resolution over the past ~50 years. Using a dynamical-systems framework, we examine the joint evolution of the overturning circulation, overturning freshwater transport, and zonally averaged potential temperature. Across all datasets, the AMOC attractor has a much lower effective complexity than suggested by the number of variables needed to describe the underlying ocean fields. Its complexity generally increases with model resolution, especially for the overturning circulation. Temperature changes dominate the slow evolution of the multi-variate attractor, but in the mesoscale permitting datasets they share almost no statistical connection with the overtuning streamfunction. The relationship between the overturning and the freshwater transport is stronger than that with temperature, but weakens for increasing resolution, and is generally stronger in ocean models than in reanalyses.  Results indicate that how relationships among AMOC, temperature, and freshwater transport are represented depend strongly on dataset considered and resolution. Based on the approximately 50-year period considered here, individual proxy variables alone may therefore provide limited information about AMOC stability and proximity to tipping points.

• PT: 8:30 am

• ET: 11:30 am

• web session:   https://teams.microsoft.com/meet/27706540266546?p=2Wdth9vqnlihf3jkYJ
  Meeting ID: 277 065 402 665 46
  Passcode: te3AE2bB

Time	Title	Presenter	Presentation	Recording	Notes

Time	Title	Presenter	Presentation	Recording	Notes
30 min	A Dynamical Systems Perspective on AMOC Across Reanalyses and Models	Alessandro Raganato Georgia Institute of Technology		Open