Lagrangian Coherent Structures and Network Approaches on Interannual Timescales in the Subpolar North Atlantic

The Atlantic meridional overturning circulation (AMOC) plays a critical role in regulating Earth’s climate by transporting heat and nutrients throughout the Atlantic Ocean. The AMOC consists of a northward-flowing surface branch of warm, saline Atlantic waters that cool as they move into subpolar regions. There, the cooling increases the water density, causing it to sink to depth in a process known as deep convection, which subsequently drives the southward branch of the AMOC in the deep ocean. Climate models suggest that increasing greenhouse gas concentrations over the past century have weakened circulation, altering AMOC variability. Subpolar regions such as the Labrador Sea, Irminger Sea, and Nordic Seas, are where deep convection influences AMOC variability. AMOC variability is an important topic because changes in circulation have direct consequences for weather patterns. The aim of the project is to first develop a computationally efficient framework that combines Lagrangian Coherent Structures and graph-theoretic measures on interannual scales to diagnose the flow of surface water and how it impacts deep convection within the subpolar regions. Once that has been established, the project will include how freshwater melt from Greenland reorganizes surface transport connectivity across subpolar regions on the interannual timescales, and how these changes influence deep convection within the AMOC.