Ocean circulation causes the largest freshening event for 120 years in eastern subpolar North Atlantic

• Published in: Nature Communications
• Main Authors: Holliday, N. Penny, Bersch, Manfred, Berx, Barbara, Chafik, Léon, Cunningham, Stuart, Florindo-López, Cristian, Hátún, Hjálmar, Johns, William, Josey, Simon, Larsen, Karin Margretha H., Mulet, Sandrine, Oltmanns, Marilena, Reverdin, Gilles, Rossby, Tom, Thierry, Virginie, Valdimarsson, Hedinn, Yashayaev, Igor
• Other Authors: National Oceanography Centre Southampton (NOC), University of Southampton, Institute of Oceanography Hamburg, University of Hamburg, Marine Scotland Science (MSS), Department of Meteorology Stockholm (MISU), Stockholm University, Bolin Centre for Climate Research, Scottish Association for Marine Science (SAMS), Faroe Marine Research Institute, Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami Coral Gables, Collecte Localisation Satellites (CLS), Helmholtz Centre for Ocean Research Kiel (GEOMAR), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Graduate School of Oceanography Narragansett, University of Rhode Island (URI), 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), Marine and Freshwater Research Institute (MFRI), Bedford Institute of Oceanography, European Project: 633211,H2020,H2020-BG-2014-2,AtlantOS(2015)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; north atlantic current; North Atlantic; North West Atlantic
• Online Access: https://hal.science/hal-03147373; https://hal.science/hal-03147373/document; https://hal.science/hal-03147373/file/s41467-020-14474-y.pdf; https://doi.org/10.1038/s41467-020-14474-y

International audience The Atlantic Ocean overturning circulation is important to the climate system because it carries heat and carbon northward, and from the surface to the deep ocean. The high salinity of the subpolar North Atlantic is a prerequisite for overturning circulation, and strong freshening could herald a slowdown. We show that the eastern subpolar North Atlantic underwent extreme freshening during 2012 to 2016, with a magnitude never seen before in 120 years of measurements. The cause was unusual winter wind patterns driving major changes in ocean circulation, including slowing of the North Atlantic Current and diversion of Arctic freshwater from the western boundary into the eastern basins. We find that winddriven routing of Arctic-origin freshwater intimately links conditions on the North West Atlantic shelf and slope region with the eastern subpolar basins. This reveals the importance of atmospheric forcing of intra-basin circulation in determining the salinity of the subpolar North Atlantic.