New insights into the eastern Subpolar North Atlantic meridional overturning circulation from OVIDE

• Published in: Ocean Science
• Main Authors: Mercier, Herle, Desbruyères, Damien, Lherminier, Pascale, Velo, Antón, Carracedo, Lidia, Fontela, Marcos, Perez, Fiz F.
• Other Authors: Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Instituto de Investigaciones Marinas y Costeras Mar del Plata (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires (CONICET)-Facultad de Ciencias Exactas y Naturales Mar del Plata, Universidad Nacional de Mar del Plata Mar del Plata (UNMdP)-Universidad Nacional de Mar del Plata Mar del Plata (UNMdP)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDU]Sciences of the Universe [physics]; Greenland; East Greenland; east greenland current; North Atlantic
• Online Access: https://hal.science/hal-04669236; https://hal.science/hal-04669236/document; https://hal.science/hal-04669236/file/os-20-779-2024.pdf; https://doi.org/10.5194/os-20-779-2024

International audience The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the Earth's climate. However, there are few long series of observations of the AMOC and the study of the mechanisms driving its variability depends mainly on numerical simulations. Here, we use four ocean circulation estimates produced by different data-driven approaches of increasing complexity to analyze the seasonal to decadal variability of the subpolar AMOC across the Greenland–Portugal OVIDE line since 1993. We show that the variance of the time series is dominated by seasonal variability, which is due to both seasonal variability in the volume of the AMOC limbs (linked to the seasonal cycle of density in the East Greenland Current) and to seasonal variability in the transport of the Eastern Boundary Current. The decadal variability of the subpolar AMOC is mainly caused by changes in velocity, which after the mid-2000s are partly offset by changes in the volume of the AMOC limbs. This compensation means that the decadal variability of the AMOC is weaker and therefore more difficult to detect than the decadal variability of its velocity-driven and volume-driven components, which is highlighted by the formalism that we propose.