1404 / 2024-09-26 20:54:11

Advances in understanding the Atlantic Meridional Overturning Circulation variability using climate models

Clima,A,Atlantic Meridional Overturning Circulation,External forcings

The Atlantic Meridional Overturning Circulation (AMOC) plays a crucial role in transporting heat northward, significantly influencing the climate of the Northern Hemisphere. Continuous AMOC observations have only been available since the early 2000s, making climate models essential tools for estimating AMOC variability. We focus on the variability simulated by successive versions of the IPSL (Institut Pierre Simon Laplace) models. In these models, the AMOC exhibits bidecadal variability driven by oceanic processes, while its multi-decadal variability is primarily influenced by salinity exchanges between the Arctic and North Atlantic. Using various numerical experiments, we demonstrate that both modes of variability are sensitive to the mean ocean state, with a notable reduction in variability in a warmer climate. Finally, we examine the sea surface temperature (SST) signature of AMOC variability and its associated climate impacts. Recent changes in subpolar SST anomalies over the past few decades are analyzed using a multi-model ensemble of climate simulations. If time allows, we will explore the role of internally-generated variability and external forcing using model simulations with observational data.