Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Climate Année : 2020

Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales

Résumé

Mechanisms driving the North Atlantic meridional overturning circulation (AMOC) variability at low frequency are of central interest for accurate climate predictions. Although the subpolar gyre region has been identified as a preferred place for generating climate timescale signals, their southward propagation remains under consideration, complicating the interpretation of the observed time series provided by the Rapid Climate Change-Meridional Overturning Circulation and Heatflux Array-Western Boundary Time Series (RAPID-MOCHA-WBTS) program. In this study, we aim at disentangling the respective contribution of the local atmospheric forcing from signals of remote origin for the subtropical low-frequency AMOC variability. We analyze for this a set of four ensembles of a regional (208S-558N), eddy-resolving (1/128) North Atlantic oceanic configuration, where surface forcing and open boundary conditions are alternatively permuted from fully varying (realistic) to yearly repeating signals. Their analysis reveals the predominance of local, atmospherically forced signal at interannual time scales (2-10 years), whereas signals imposed by the boundaries are responsible for the decadal (10-30 years) part of the spectrum. Due to this marked timescale separation, we show that, although the intergyre region exhibits peculiarities, most of the subtropical AMOC variability can be understood as a linear superposition of these two signals. Finally, we find that the decadal-scale, boundary-forced AMOC variability has both northern and southern origins, although the former dominates over the latter, including at the site of the RAPID array (26.58N).

Domaines

Océanographie
Fichier principal
Vignette du fichier
Jamet2020.pdf (4.49 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-02879821 , version 1 (24-06-2020)

Identifiants

Citer

Quentin Jamet, William K Dewar, Nicolas Wienders, Bruno Deremble, Sally Close, et al.. Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales. Journal of Climate, 2020, ⟨10.1175/JCLI-D-19-0844.1⟩. ⟨hal-02879821⟩
63 Consultations
30 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More