AMOC transport variability and coherence from observations and models

The Atlantic Meridional Overturning Circulation (AMOC) is a fundamental component of the climate system, transporting heat, freshwater, and momentum across the Atlantic basin and playing a critical role in regulating regional climate and global heat uptake. It is commonly portrayed as a conveyor belt, with warm saline waters travelling northward, losing heat to the atmosphere and freshening due to precipitation and ice melt. Sinking occurs at high latitudes once the water is sufficiently dense, and the newly formed dense waters travel southward. However, this picture is overly simplistic. The AMOC is not spatially uniform: transport anomalies at one latitude do not always map directly to anomalies elsewhere, because of internal recirculations, gyre-scale compensations, mixing, and local forcing.

Within the EU-funded EPOC (Explaining and Predicting the Ocean Conveyor) project we have examined transport variability and coherence on seasonal and longer timescales in observations and a range of numerical models. Starting from the Arctic gateways and progressing southward, transports and variability of volume, heat and freshwater are compared at key observational sections are compared. Meridional coherence of the AMOC is examined using latitude-correlation and EOF decomposition methods, and comparisons against recent Bayesian modelling heat and observation-based freshwater transports are made. In this poster we summarise the key analysis and work performed under WP1.

This work is funded by the UKRI (grant number 10038003) as part of the EPOC project (Explaining and Predicting the Ocean Conveyor; grant number: 101059547).