WHOI PO

Title: Regime Shifts of AMOC-Sea Surface Temperature Relationship
Abstract: The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the climate system, and North Atlantic sea-surface temperature (SST) patterns are often used as an indirect indicator of AMOC variability. However, the relationship between AMOC and SST fingerprints may not be stationary across different climate states. In this seminar, I will present results from my recent study showing that the AMOC–SST relationship is state-dependent. Using CESM simulations spanning multiple climate states, together with a multi-model ensemble, we identify three distinct regimes: a strong-AMOC regime with a commonly-known North Atlantic dipole fingerprint, an intermediate regime with amplified subpolar SST anomalies, and a weak-AMOC regime in which North Atlantic SST signals become muted. These regime shifts are directly linked to atmospheric radiative processes, while ocean processes play an indirect role through air–sea interactions. I will also discuss how the year of peak AMOC–SST sensitivity can be used as a predictor for the transition into the weak-AMOC regime and for the decay of the North Atlantic warming hole, providing a physically based constraint on model uncertainty in climate projections.