ORTEGA, Pablo; MIGNOT, Juliette; SWINGEDOUW, Didier; SÉVELLEC, Florian; GUILYARDI, Éric

doi:10.1016/j.pocean.2015.06.009

MIGNOT, Juliette
Processus de la variabilité climatique tropicale et impacts [PARVATI]
Oeschger Centre for Climate Change Research [OCCR]

SWINGEDOUW, Didier

Environnements et Paléoenvironnements OCéaniques [EPOC]

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Article de revue

Ce document a été publié dans

Progress in Oceanography. 2015-09, vol. 137, n° Part A, p. 237–249

Résumé en anglais

Understanding the preferential timescales of variability in the North Atlantic, usually associated with the Atlantic meridional overturning circulation (AMOC), is essential for the prospects for decadal prediction. However, the wide variety of mechanisms proposed from the analysis of climate simulations, potentially dependent on the models themselves, has stimulated the debate of which processes take place in reality. One mechanism receiving increasing attention, identified both in idealized models and observations, is a westward propagation of subsurface buoyancy anomalies that impact the AMOC through a basin-scale intensification of the zonal density gradient, enhancing the northward transport via thermal wind balance. In this study, we revisit a control simulation from the Institut Pierre-Simon Laplace Coupled Model 5A (IPSL-CM5A), characterized by a strong AMOC periodicity at 20 years, previously explained by an upper ocean–atmosphere–sea ice coupled mode driving convection activity south of Iceland. Our study shows that this mechanism interacts constructively with the basin-wide propagation in the subsurface. This constructive feedback may explain why bi-decadal variability is so intense in this coupled model as compared to others.< Réduire

URI

https://oskar-bordeaux.fr/handle/20.500.12278/200209

DOI

http://dx.doi.org/10.1016/j.pocean.2015.06.009

Projet Européen

Seasonal-to-decadal climate Prediction for the improvement of EuropeanClimate Services

Project ANR

Oscillations et rétroactions climatiques aux échelles décennales : mécanismes, sensibilité et incertitudes - ANR-13-SENV-0002

Unités de recherche

EPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805

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Reconciling two alternative mechanisms behind bi-decadal variability in the North Atlantic