Damping of climate-scale oceanic variability by mesoscale eddy turbulence

• Published in: Journal of Physical Oceanography
• Main Authors: Sévellec, Florian, Naveira Garabato, Alberto, Huck, Thierry
• Other Authors: 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)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Interdisciplinary Graduate School for the Blue planet (ISblue), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Ocean; Southern Ocean; Eddies; Large-scale motions; Nonlinear dynamics; In situ oceanic observations; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; The Antarctic; Drake Passage; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-03004064; https://hal.archives-ouvertes.fr/hal-03004064/document; https://hal.archives-ouvertes.fr/hal-03004064/file/Sevellec_et_al_JPO2020inpress.pdf; https://doi.org/10.1175/JPO-D-20-0141.1

International audience The impact of mesoscale eddy turbulence on long-term, climatic variability in the ocean's buoyancy structure is investigated using observations from a mooring deployed in the Drake Passage, Southern Ocean. By applying the Temporal-Residual-Mean framework and characterizing the variance contributors and the buoyancy variance budget, we identify the main source and sink of long-term buoyancy variance. Long-term buoyancy variance amplitude is set by long-term vertical velocity fluctuations acting on the steady stratification. This baro-clinic buoyancy flux is also the main source of the variance, indicative of the effect of large-scale baroclinic instability. This source is balanced by a sink of long-term buoyancy variance associated with the vertical advection of the steady stratification by the eddy-induced circulation. We conclude that mesoscale eddy turbulence acts as a damping mechanism for long-term, climatic variability in the region of the observations, consistent with an ‘eddy saturated’ behaviour of the Antarctic Circumpolar Current.