Articles | Volume 19, issue 3
Research article
 | Highlight paper
06 Jun 2023
Research article | Highlight paper |  | 06 Jun 2023

Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective

Oliver John Tooth, Helen Louise Johnson, Chris Wilson, and Dafydd Gwyn Evans

Data sets

Lagrangian overturning in the eastern subpolar North Atlantic Ocean - ORCA025-GJM189 Particle Trajectory Dataset Oliver John Tooth

Model code and software

TRACMASS: Formal release of version 7.0 (v7.0-beta) Aitor Aldama-Campino, Kristofer Döös, Joakim Kjellsson, and Bror Jönsson

meom-configurations/ORCA025.L75-GJM189 (V-1.1) Jean-Marc Molines

The authors investigate the main contributors to the seasonal variability in the strength of the Atlantic Meridional Overturning Circulation in the eastern North Atlantic subpolar gyre using a Lagrangian approach. They analyze trajectories from a hindcast model that permits eddies. The insights gained from the study are important and of interest to the broader scientific community, as well as potentially to the public. Specifically, the study finds that the strong seasonality in the strength of the AMOC is explained by the rapid circulation of upper limb waters. Parcels with sufficiently long circulation times within the gyre experience a combination of surface buoyancy loss and interior mixing, which filters out their seasonal thermohaline variability.
Short summary
This study uses the trajectories of water parcels traced within an ocean model simulation to identify the pathways responsible for the seasonal cycle of dense water formation (overturning) in the eastern subpolar North Atlantic. We show that overturning seasonality is due to the fastest water parcels circulating within the eastern basins in less than 8.5 months. Slower pathways set the average strength of overturning in this region since water parcels cannot escape intense wintertime cooling.