On the Role of Atmospheric Forcing on the North Atlantic Dynamic – Insights from Observations and Climate Models

The Atlantic Meridional Overturning Circulation (AMOC) plays a major role in shaping the Northern Hemisphere climate, and assessing the risk of a future slowdown has become a key challenge in ocean research. Over the past two decades, advances in observations and modeling have substantially refined our understanding of where and how deep waters are formed.

In this ‎Award Lecture of the OS‎ Division, I will review these developments to examine the drivers of North Atlantic dynamics and their representation in coupled climate models. First, I will focus on observation-based estimates of water mass transformation in the subpolar gyre, highlighting the dominant role of local buoyancy forcing in the Irminger and Iceland basins. Second, I will examine how deep water formation is simulated in coupled climate models, identifying key biases that lead to excessive formation in the Labrador Sea and assessing their implications for the AMOC at subpolar latitudes. Finally, I will discuss the southward propagation of deep waters and the coherence of AMOC variability across the North Atlantic, placing these results in the broader context of AMOC change at different timescale.