Mass, nutrient and oxygen budgets for the northeastern Atlantic Ocean

• Published in: Biogeosciences
• Main Authors: Maze, G., Mercier, H., Thierry, V., Mémery, Laurent, Morin, Pascal, Perez, F. 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 des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), CHImie Marine (CHIM), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Científicas Madrid (CSIC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2012
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Greenland; Reykjanes; Irminger Sea; Greenland-Scotland Ridge; Nordic Seas; Northeast Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-00784718; https://hal.archives-ouvertes.fr/hal-00784718/document; https://hal.archives-ouvertes.fr/hal-00784718/file/Mass_nutrient_oxygen.pdf; https://doi.org/10.5194/bg-9-4099-2012

International audience The northeast Atlantic is a key horizontal and vertical crossroads region for the meridional overturning circulation, but basic nutrient and oxygen fluxes are still poorly constrained by observations in the region. A surface to bottom northeast Atlantic Ocean budget for mass, nutrients (nitrate and phosphate) and oxygen is determined using an optimization method based on three surveys of the OVIDE transect (from Greenland to Portugal) completed with the World Ocean Atlas 2009. Budgets are derived for two communicating boxes representing the northeastern European basin (NEEB) and the Irminger Sea. For the NEEB (Irminger) box, it is found that 30% of the mass import (export) across the OVIDE section reach (originate from) the Nordic Seas, while 70% are redistributed between both boxes through the Reykjanes Ridge (9.3±0.7×109 kg s−1). Net biological source/sink terms of nitrate point to both the Irminger and NEEB boxes as net organic matter production sites (consuming nitrate at a rate of −7.8±6.5 kmol s−1 and −8.4±6.6 kmol s−1, respectively). Using a standard Redfield ratio of C :N= 106 : 16, nitrate consumption rates indicate that about 40 TgC yr−1 of carbon is fixed by organic matter production between the OVIDE transect and the Greenland-Scotland Ridge. Nutrient fluxes also induce a net biological production of oxygen of 73±60 kmol s−1 and 79±62 kmol s−1 in the Irminger and NEEB boxes, which points to the region as being autotrophic. The abiotic air-sea oxygen flux leads to an oceanic oxygen uptake in the two regions (264±66 kmol s−1 in the north and 443±70 kmol s−1 in the south). The abiotic flux is partitioned into a mixing and a thermal component. It is found that the Irminger Sea oceanic oxygen uptake is driven by an air-sea heat flux cooling increasing the ocean surface oxygen solubility. Over the northeastern European basin the mixing component is about half the thermal flux, presumably because of the oxygen minimum in the subtropical thermocline.