A global hybrid coupled model based on Atmosphere-SST feedbacks

TL;DR

This paper introduces a fast, hybrid climate model combining a global ocean model with a statistical atmosphere component to study Atlantic circulation stability and feedbacks efficiently.

Contribution

It develops a hybrid coupled model that captures key ocean-atmosphere feedbacks and is significantly faster than fully coupled models, while maintaining similar climate responses.

Findings

Model reaches a steady state similar to fully coupled climate models.

Replicates the collapse of Atlantic meridional overturning circulation under freshwater forcing.

More than ten times faster than traditional fully coupled climate models.

Abstract

A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater and wind-stress. A basic but consistent representation of ocean-atmosphere feedbacks is captured in the hybrid coupled model and it is more than ten times faster than the fully coupled climate model. The hybrid coupled model reaches a steady state with a climate close to the one of the fully coupled climate model, and the two models also have a similar response (collapse) of the Atlantic meridional overturning circulation to a freshwater hosing applied in the northern North Atlantic.