Variability of the thermohaline circulation of the North Atlantic: Sensitivity to overflows of dense water masses

• Published in: Ocean Dynamics
• Main Authors: Beismann, Jens-Olaf, Barnier, Bernard
• Other Authors: Technische Fakultät der Universität Kiel, Kiel, Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2004
• Subjects: [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]; [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]; Nordic Seas; North Atlantic
• Online Access: https://hal.science/hal-00182980; https://hal.science/hal-00182980/document; https://hal.science/hal-00182980/file/Beismann2004.pdf; https://doi.org/10.1007/s10236-003-0088-x

A numerical model of the Atlantic Ocean was used to study the low-frequency variability of meridi-onal transports in the North Atlantic. The model shows a behaviour similar to those used in previous studies, and the temporal variability of certain variables compares favourably to observed time series. By changing the depth and width of the sills between the subpolar North Atlantic and the Nordic Seas, the mean horizontal and overturning circulation as well as some water mass properties are modified significantly. The reaction of meridional oceanic transports to atmospheric forcing fluctuations remains, however, unchanged. The critical role of the surface heat flux retroaction term for the meridional heat transport in stand-alone ocean models is discussed. The experiments underline the role of atmospheric variability for fluctuations of the large-scale ocean circulation on time scales from years to decades, and they support the hypothesis that the mean overturning strength is controlled by the model representation of the density of the overflow water masses.