Water mass analysis along 22 [degrees]N in the subtropical North Atlantic for the JC150 cruise (GEOTRACES, GApr08).

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Publisher: Elsevier B.V.
Document Type: Report
Length: 546 words

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Keywords Water mass; Optimum multiparameter analysis (OMPA); Lagrangian particle tracking experiment; Subtropical north Atlantic; JC150; GEOTRACES Highlights * Optimum multiparameter analysis combined with a Lagrangian particle tracking experiment. * Impact of Amazon River plume identified as north as 22°N. * Mediterranean Water impact on North Atlantic Deep Water salinity as deep as 3500 m. * Un-previously described Labrador Sea Water route in the eastern North Atlantic. * North West Atlantic Bottom Water transport across the Mid-Atlantic Ridge. Abstract This study presents a water mass analysis along the JC150 section in the subtropical North Atlantic, based on hydrographic and nutrient data, by combining an extended optimum multiparameter analysis (OMPA) with a Lagrangian particle tracking experiment (LPTE). This combination, which was proposed for the first time, aided in better constraining the OMPA end-member choice and providing information about their trajectories. It also enabled tracing the water mass origins in surface layers, which cannot be achieved with an OMPA. The surface layers were occupied by a shallow type of Eastern South Atlantic Central Water (ESACW) with traces of the Amazon plume in the west. Western North Atlantic Central Water dominates from 100 to 500 m, while the 13 °C-ESACW contribution occurs marginally deeper (500--900 m). At approximately 700 m, Antarctic Intermediate Water (AAIW) dominates the west of the Mid-Atlantic Ridge (MAR), while Mediterranean Water dominates the east with a small but non-negligible contribution down to 3500 m. Below AAIW, Upper Circumpolar Deep Water (UCDW) is observed throughout section (900--1250 m). Labrador Sea Water (LSW) is found centered at 1500 m, where the LPTE highlights an eastern LSW route from the eastern North Atlantic to the eastern subtropical Atlantic, which was not previously reported. North East Atlantic Deep Water (encompassing a contribution of Iceland-Scotland Overflow Water) is centered at ~2500 m, while North West Atlantic Bottom Water (NWABW, encompassing a contribution of Denmark Strait Overflow Water) is principally localized in the west of the MAR in the range of 3500--5000 m. NWABW is also present in significant proportions ( 25%) in the east of the MAR, suggesting a crossing of the MAR possibly through the Kane fracture zone. This feature has not been investigated so far. Finally, Antarctic Bottom Water is present in deep waters throughout the section, mainly in the west of the MAR. Source waters have been characterized from GEOTRACES sections, which enables estimations of trace elements and isotope transport within water masses in the subtropical North Atlantic. Abbreviations LPTE, Lagrangian Particle Tracking Experiment Author Affiliation: (a) LEGOS, University of Toulouse, CNRS, CNES, IRD, UPS, 31400, Toulouse, France (b) Mercator Ocean International, Ramonville Saint-Agne, France (c) Ocean and Earth Science, University of Southampton, National Oceanographic Center, Southampton, SO14 3ZH, UK (d) Plymouth Marine Laboratory, Plymouth, PL1 3DH, UK (e) Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, 4 Brownlow Street, University of Liverpool, Liverpool, L69 3GP, UK (f) National Oceanography Centre, Liverpool, L3 5DA, UK * Corresponding author. LEGOS/CNES, 18, avenue Edouard Belin, 31401, Toulouse Cedex 9, France. Article History: Received 29 June 2019; Revised 26 January 2020; Accepted 27 January 2020 Byline: Lise Artigue [lise.artigue@legos.obs-mip.fr] (a,*), François Lacan (a), Simon van Gennip (b), Maeve C. Lohan (c), Neil J. Wyatt (c), E. Malcolm S. Woodward (d), Claire Mahaffey (e), Joanne Hopkins (f), Yann Drillet (b)

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Gale Document Number: GALE|A618367168