The Meridional Overturning Circulation in the Sub-Polar North Atlantic Ocean: a Model-Observation Comparison

The Meridional Overturning Circulation (MOC) is a key component of the Earth's climate system as it contributes to the redistribution of heat, salt and anthropogenic carbon in the world ocean. The variability of the MOC is widely studied and results have shown that there is a strong variability of transport in the subpolar North Atlantic Ocean. The observational program OSNAP provides a multiyear continuous measure of the Atlantic Meridional Overturning Circulation (AMOC) and the associated transports in the subpolar North Atlantic. Previous numerical studies have also shown that the variability of the AMOC is linked to the formation of Labrador Sea Water (LSW). However, the impact of the formation of the LSW on the AMOC remains unclear and is still under debate. Especially, there is no observational evidence of this link. In this study, we analyze the variability of the AMOC at the OSNAP array using the observational data and an ocean simulation. We use a simulations from the DRAKKAR project: an eddy permitting 1/12 degree Arctic and Northern Hemisphere Atlantic (ANHA) configuration, and covering the time period from 2002 to 2018. We will address the differences and similarities between the model and the observations to understand the driving mechanisms in the variability of the AMOC at the OSNAP array (transport in the boundary currents, transport in the interior and Ekman transport), as well as in what extent the formation of the LSW plays a role in the variability of the AMOC.