Articles | Volume 19, issue 2
https://doi.org/10.5194/bg-19-437-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-19-437-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
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28 Jan 2022
Research article | Highlight paper |
| 28 Jan 2022
| 28 Jan 2022
Oxygen export to the deep ocean following Labrador Sea Water formation
Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
Dariia Atamanchuk
Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
Johannes Karstensen
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Patricia Handmann
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Douglas W. R. Wallace
Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
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Yan Barabinot, Sabrina Speich, Xavier Carton, Pierre L'Hégaret, Corentin Subirade, Rémi Laxenaire, and Johannes Karstensen
Ocean Sci., 21, 1849–1872, https://doi.org/10.5194/os-21-1849-2025, https://doi.org/10.5194/os-21-1849-2025, 2025
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Mesoscale eddies are rotating oceanic currents key to ocean variability. Off Brazil’s northeast coast, the North Brazil Current generates on average 4.5 eddies per year, which drift towards the West Indies, transporting waters from the Southern Hemisphere. Using data collected at sea by the EUREC4A-OA cruise, this study reveals that deep eddies transport 5 times more water than surface ones, reshaping our understanding of the regional water transport.
Lennart Gerke, Toste Tanhua, William A. Nesbitt, Samuel W. Stevens, and Douglas W. R. Wallace
EGUsphere, https://doi.org/10.5194/egusphere-2025-3999, https://doi.org/10.5194/egusphere-2025-3999, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
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Transient tracer data, measured for the first time in 2022 in the Gulf of St. Lawrence, reveal older deep waters in the east than the west, contrary to expected estuarine circulation, indicating increased influence of older, warmer, less oxygenated North Atlantic Central Water over younger, oxygen-rich Labrador Current Water. While consistent with previous reports of increasing NACW contribution, our results contradict claims of a complete shift to NACW by 2021, showing that LCW still persists.
Arnaud Laurent, Bin Wang, Dariia Atamanchuk, Subhadeep Rakshit, Kumiko Azetsu-Scott, Chris Algar, and Katja Fennel
EGUsphere, https://doi.org/10.5194/egusphere-2025-3361, https://doi.org/10.5194/egusphere-2025-3361, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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Surface ocean alkalinity enhancement, through the release of alkaline materials, is a technology that could increase the storage of anthropogenic carbon in the ocean. Halifax Harbour (Canada) is a current test site for operational alkalinity addition. Here, we present a model of Halifax Harbour that simulates alkalinity addition at various locations of the harbour and quantifies the resulting net CO2 uptake. The model can be relocated to study alkalinity addition in other coastal systems.
William A. Nesbitt, Samuel W. Stevens, Alfonso O. Mucci, Lennart Gerke, Toste Tanhua, Gwénaëlle Chaillou, and Douglas W. R. Wallace
EGUsphere, https://doi.org/10.5194/egusphere-2025-2400, https://doi.org/10.5194/egusphere-2025-2400, 2025
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We use 20 years of oxygen measurements and recent carbon data with a tracer-calibrated 1D model to quantify oxygen loss and inorganic carbon accumulation in the deep waters of the Gulf and St. Lawrence Estuary. We further utilize the model to give a first estimate of the impact of adding pure oxygen, a by-product from green hydrogen production to these deep waters. Results show this could restore oxygen to year-2000 levels, but full recovery would require a larger input.
Taavi Liblik, Daniel Rak, Enriko Siht, Germo Väli, Johannes Karstensen, Laura Tuomi, Louise C. Biddle, Madis-Jaak Lilover, Māris Skudra, Michael Naumann, Urmas Lips, and Volker Mohrholz
EGUsphere, https://doi.org/10.5194/egusphere-2024-2272, https://doi.org/10.5194/egusphere-2024-2272, 2024
Preprint archived
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Eight current meters were deployed to the seafloor across the Baltic to enhance knowledge about circulation and currents. The experiment was complemented by autonomous vehicles. Stable circulation patterns were observed at the sea when weather was steady. Strong and quite persistent currents were observed at the key passage for the deep-water renewal of the Northern Baltic Sea. Deep water renewal mostly occurs during spring and summer periods in the northern Baltic Sea.
Alizée Dale, Marion Gehlen, Douglas W. R. Wallace, Germain Bénard, Christian Éthé, and Elena Alekseenko
EGUsphere, https://doi.org/10.5194/egusphere-2023-2538, https://doi.org/10.5194/egusphere-2023-2538, 2023
Preprint archived
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Diatom, which is at the base of a productive food chain that supports valuable fisheries, dominates the total primary production of the Labrador Sea (LS). The synthesis of biogenic silica frustules makes them peculiar among phytoplankton but also dependent on dissolved silicate (DSi). Regular oceanographic surveys show declining DSi concentrations since the mid-1990s. With a model-based approach, we show that weakening deep winter convection was the proximate cause of DSi decline in the LS.
Pierre L'Hégaret, Florian Schütte, Sabrina Speich, Gilles Reverdin, Dariusz B. Baranowski, Rena Czeschel, Tim Fischer, Gregory R. Foltz, Karen J. Heywood, Gerd Krahmann, Rémi Laxenaire, Caroline Le Bihan, Philippe Le Bot, Stéphane Leizour, Callum Rollo, Michael Schlundt, Elizabeth Siddle, Corentin Subirade, Dongxiao Zhang, and Johannes Karstensen
Earth Syst. Sci. Data, 15, 1801–1830, https://doi.org/10.5194/essd-15-1801-2023, https://doi.org/10.5194/essd-15-1801-2023, 2023
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In early 2020, the EUREC4A-OA/ATOMIC experiment took place in the northwestern Tropical Atlantic Ocean, a dynamical region where different water masses interact. Four oceanographic vessels and a fleet of autonomous devices were deployed to study the processes at play and sample the upper ocean, each with its own observing capability. The article first describes the data calibration and validation and second their cross-validation, using a hierarchy of instruments and estimating the uncertainty.
Mathilde Jutras, Alfonso Mucci, Gwenaëlle Chaillou, William A. Nesbitt, and Douglas W. R. Wallace
Biogeosciences, 20, 839–849, https://doi.org/10.5194/bg-20-839-2023, https://doi.org/10.5194/bg-20-839-2023, 2023
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The deep waters of the lower St Lawrence Estuary and gulf have, in the last decades, experienced a strong decline in their oxygen concentration. Below 65 µmol L-1, the waters are said to be hypoxic, with dire consequences for marine life. We show that the extent of the hypoxic zone shows a seven-fold increase in the last 20 years, reaching 9400 km2 in 2021. After a stable period at ~ 65 µmol L⁻¹ from 1984 to 2019, the oxygen level also suddenly decreased to ~ 35 µmol L-1 in 2020.
Alan D. Fox, Patricia Handmann, Christina Schmidt, Neil Fraser, Siren Rühs, Alejandra Sanchez-Franks, Torge Martin, Marilena Oltmanns, Clare Johnson, Willi Rath, N. Penny Holliday, Arne Biastoch, Stuart A. Cunningham, and Igor Yashayaev
Ocean Sci., 18, 1507–1533, https://doi.org/10.5194/os-18-1507-2022, https://doi.org/10.5194/os-18-1507-2022, 2022
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Observations of the eastern subpolar North Atlantic in the 2010s show exceptional freshening and cooling of the upper ocean, peaking in 2016 with the lowest salinities recorded for 120 years. Using results from a high-resolution ocean model, supported by observations, we propose that the leading cause is reduced surface cooling over the preceding decade in the Labrador Sea, leading to increased outflow of less dense water and so to freshening and cooling of the eastern subpolar North Atlantic.
Jörg Fröhle, Patricia V. K. Handmann, and Arne Biastoch
Ocean Sci., 18, 1431–1450, https://doi.org/10.5194/os-18-1431-2022, https://doi.org/10.5194/os-18-1431-2022, 2022
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Three deep-water masses pass the southern exit of the Labrador Sea. Usually they are defined by explicit density intervals linked to the formation region. We evaluate this relation in an ocean model by backtracking the paths the water follows for 40 years: 48 % densify without contact to the atmosphere, 24 % densify in contact with the atmosphere, and 19 % are from the Nordic Seas. All three contribute to a similar density range at 53° N with weak specific formation location characteristics.
Rainer Kiko, Marc Picheral, David Antoine, Marcel Babin, Léo Berline, Tristan Biard, Emmanuel Boss, Peter Brandt, Francois Carlotti, Svenja Christiansen, Laurent Coppola, Leandro de la Cruz, Emilie Diamond-Riquier, Xavier Durrieu de Madron, Amanda Elineau, Gabriel Gorsky, Lionel Guidi, Helena Hauss, Jean-Olivier Irisson, Lee Karp-Boss, Johannes Karstensen, Dong-gyun Kim, Rachel M. Lekanoff, Fabien Lombard, Rubens M. Lopes, Claudie Marec, Andrew M. P. McDonnell, Daniela Niemeyer, Margaux Noyon, Stephanie H. O'Daly, Mark D. Ohman, Jessica L. Pretty, Andreas Rogge, Sarah Searson, Masashi Shibata, Yuji Tanaka, Toste Tanhua, Jan Taucher, Emilia Trudnowska, Jessica S. Turner, Anya Waite, and Lars Stemmann
Earth Syst. Sci. Data, 14, 4315–4337, https://doi.org/10.5194/essd-14-4315-2022, https://doi.org/10.5194/essd-14-4315-2022, 2022
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The term
marine particlescomprises detrital aggregates; fecal pellets; bacterioplankton, phytoplankton and zooplankton; and even fish. Here, we present a global dataset that contains 8805 vertical particle size distribution profiles obtained with Underwater Vision Profiler 5 (UVP5) camera systems. These data are valuable to the scientific community, as they can be used to constrain important biogeochemical processes in the ocean, such as the flux of carbon to the deep sea.
Léa Olivier, Jacqueline Boutin, Gilles Reverdin, Nathalie Lefèvre, Peter Landschützer, Sabrina Speich, Johannes Karstensen, Matthieu Labaste, Christophe Noisel, Markus Ritschel, Tobias Steinhoff, and Rik Wanninkhof
Biogeosciences, 19, 2969–2988, https://doi.org/10.5194/bg-19-2969-2022, https://doi.org/10.5194/bg-19-2969-2022, 2022
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We investigate the impact of the interactions between eddies and the Amazon River plume on the CO2 air–sea fluxes to better characterize the ocean carbon sink in winter 2020. The region is a strong CO2 sink, previously underestimated by a factor of 10 due to a lack of data and understanding of the processes responsible for the variability in ocean carbon parameters. The CO2 absorption is mainly driven by freshwater from the Amazon entrained by eddies and by the winter seasonal cooling.
Gerhard Fischer, Oscar E. Romero, Johannes Karstensen, Karl-Heinz Baumann, Nasrollah Moradi, Morten Iversen, Götz Ruhland, Marco Klann, and Arne Körtzinger
Biogeosciences, 18, 6479–6500, https://doi.org/10.5194/bg-18-6479-2021, https://doi.org/10.5194/bg-18-6479-2021, 2021
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Low-oxygen eddies in the eastern subtropical North Atlantic can form an oasis for phytoplankton growth. Here we report on particle flux dynamics at the oligotrophic Cape Verde Ocean Observatory. We observed consistent flux patterns during the passages of low-oxygen eddies. We found distinct flux peaks in late winter, clearly exceeding background fluxes. Our findings suggest that the low-oxygen eddies sequester higher organic carbon than expected for oligotrophic settings.
Krysten Rutherford, Katja Fennel, Dariia Atamanchuk, Douglas Wallace, and Helmuth Thomas
Biogeosciences, 18, 6271–6286, https://doi.org/10.5194/bg-18-6271-2021, https://doi.org/10.5194/bg-18-6271-2021, 2021
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Using a regional model of the northwestern North Atlantic shelves in combination with a surface water time series and repeat transect observations, we investigate surface CO2 variability on the Scotian Shelf. The study highlights a strong seasonal cycle in shelf-wide pCO2 and spatial variability throughout the summer months driven by physical events. The simulated net flux of CO2 on the Scotian Shelf is out of the ocean, deviating from the global air–sea CO2 flux trend in continental shelves.
Arne Biastoch, Franziska U. Schwarzkopf, Klaus Getzlaff, Siren Rühs, Torge Martin, Markus Scheinert, Tobias Schulzki, Patricia Handmann, Rebecca Hummels, and Claus W. Böning
Ocean Sci., 17, 1177–1211, https://doi.org/10.5194/os-17-1177-2021, https://doi.org/10.5194/os-17-1177-2021, 2021
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The Atlantic Meridional Overturning Circulation (AMOC) quantifies the impact of the ocean on climate and climate change. Here we show that a high-resolution ocean model is able to realistically simulate ocean currents. While the mean representation of the AMOC depends on choices made for the model and on the atmospheric forcing, the temporal variability is quite robust. Comparing the ocean model with ocean observations, we able to identify that the AMOC has declined over the past two decades.
Bjorn Stevens, Sandrine Bony, David Farrell, Felix Ament, Alan Blyth, Christopher Fairall, Johannes Karstensen, Patricia K. Quinn, Sabrina Speich, Claudia Acquistapace, Franziska Aemisegger, Anna Lea Albright, Hugo Bellenger, Eberhard Bodenschatz, Kathy-Ann Caesar, Rebecca Chewitt-Lucas, Gijs de Boer, Julien Delanoë, Leif Denby, Florian Ewald, Benjamin Fildier, Marvin Forde, Geet George, Silke Gross, Martin Hagen, Andrea Hausold, Karen J. Heywood, Lutz Hirsch, Marek Jacob, Friedhelm Jansen, Stefan Kinne, Daniel Klocke, Tobias Kölling, Heike Konow, Marie Lothon, Wiebke Mohr, Ann Kristin Naumann, Louise Nuijens, Léa Olivier, Robert Pincus, Mira Pöhlker, Gilles Reverdin, Gregory Roberts, Sabrina Schnitt, Hauke Schulz, A. Pier Siebesma, Claudia Christine Stephan, Peter Sullivan, Ludovic Touzé-Peiffer, Jessica Vial, Raphaela Vogel, Paquita Zuidema, Nicola Alexander, Lyndon Alves, Sophian Arixi, Hamish Asmath, Gholamhossein Bagheri, Katharina Baier, Adriana Bailey, Dariusz Baranowski, Alexandre Baron, Sébastien Barrau, Paul A. Barrett, Frédéric Batier, Andreas Behrendt, Arne Bendinger, Florent Beucher, Sebastien Bigorre, Edmund Blades, Peter Blossey, Olivier Bock, Steven Böing, Pierre Bosser, Denis Bourras, Pascale Bouruet-Aubertot, Keith Bower, Pierre Branellec, Hubert Branger, Michal Brennek, Alan Brewer, Pierre-Etienne Brilouet, Björn Brügmann, Stefan A. Buehler, Elmo Burke, Ralph Burton, Radiance Calmer, Jean-Christophe Canonici, Xavier Carton, Gregory Cato Jr., Jude Andre Charles, Patrick Chazette, Yanxu Chen, Michal T. Chilinski, Thomas Choularton, Patrick Chuang, Shamal Clarke, Hugh Coe, Céline Cornet, Pierre Coutris, Fleur Couvreux, Susanne Crewell, Timothy Cronin, Zhiqiang Cui, Yannis Cuypers, Alton Daley, Gillian M. Damerell, Thibaut Dauhut, Hartwig Deneke, Jean-Philippe Desbios, Steffen Dörner, Sebastian Donner, Vincent Douet, Kyla Drushka, Marina Dütsch, André Ehrlich, Kerry Emanuel, Alexandros Emmanouilidis, Jean-Claude Etienne, Sheryl Etienne-Leblanc, Ghislain Faure, Graham Feingold, Luca Ferrero, Andreas Fix, Cyrille Flamant, Piotr Jacek Flatau, Gregory R. Foltz, Linda Forster, Iulian Furtuna, Alan Gadian, Joseph Galewsky, Martin Gallagher, Peter Gallimore, Cassandra Gaston, Chelle Gentemann, Nicolas Geyskens, Andreas Giez, John Gollop, Isabelle Gouirand, Christophe Gourbeyre, Dörte de Graaf, Geiske E. de Groot, Robert Grosz, Johannes Güttler, Manuel Gutleben, Kashawn Hall, George Harris, Kevin C. Helfer, Dean Henze, Calvert Herbert, Bruna Holanda, Antonio Ibanez-Landeta, Janet Intrieri, Suneil Iyer, Fabrice Julien, Heike Kalesse, Jan Kazil, Alexander Kellman, Abiel T. Kidane, Ulrike Kirchner, Marcus Klingebiel, Mareike Körner, Leslie Ann Kremper, Jan Kretzschmar, Ovid Krüger, Wojciech Kumala, Armin Kurz, Pierre L'Hégaret, Matthieu Labaste, Tom Lachlan-Cope, Arlene Laing, Peter Landschützer, Theresa Lang, Diego Lange, Ingo Lange, Clément Laplace, Gauke Lavik, Rémi Laxenaire, Caroline Le Bihan, Mason Leandro, Nathalie Lefevre, Marius Lena, Donald Lenschow, Qiang Li, Gary Lloyd, Sebastian Los, Niccolò Losi, Oscar Lovell, Christopher Luneau, Przemyslaw Makuch, Szymon Malinowski, Gaston Manta, Eleni Marinou, Nicholas Marsden, Sebastien Masson, Nicolas Maury, Bernhard Mayer, Margarette Mayers-Als, Christophe Mazel, Wayne McGeary, James C. McWilliams, Mario Mech, Melina Mehlmann, Agostino Niyonkuru Meroni, Theresa Mieslinger, Andreas Minikin, Peter Minnett, Gregor Möller, Yanmichel Morfa Avalos, Caroline Muller, Ionela Musat, Anna Napoli, Almuth Neuberger, Christophe Noisel, David Noone, Freja Nordsiek, Jakub L. Nowak, Lothar Oswald, Douglas J. Parker, Carolyn Peck, Renaud Person, Miriam Philippi, Albert Plueddemann, Christopher Pöhlker, Veronika Pörtge, Ulrich Pöschl, Lawrence Pologne, Michał Posyniak, Marc Prange, Estefanía Quiñones Meléndez, Jule Radtke, Karim Ramage, Jens Reimann, Lionel Renault, Klaus Reus, Ashford Reyes, Joachim Ribbe, Maximilian Ringel, Markus Ritschel, Cesar B. Rocha, Nicolas Rochetin, Johannes Röttenbacher, Callum Rollo, Haley Royer, Pauline Sadoulet, Leo Saffin, Sanola Sandiford, Irina Sandu, Michael Schäfer, Vera Schemann, Imke Schirmacher, Oliver Schlenczek, Jerome Schmidt, Marcel Schröder, Alfons Schwarzenboeck, Andrea Sealy, Christoph J. Senff, Ilya Serikov, Samkeyat Shohan, Elizabeth Siddle, Alexander Smirnov, Florian Späth, Branden Spooner, M. Katharina Stolla, Wojciech Szkółka, Simon P. de Szoeke, Stéphane Tarot, Eleni Tetoni, Elizabeth Thompson, Jim Thomson, Lorenzo Tomassini, Julien Totems, Alma Anna Ubele, Leonie Villiger, Jan von Arx, Thomas Wagner, Andi Walther, Ben Webber, Manfred Wendisch, Shanice Whitehall, Anton Wiltshire, Allison A. Wing, Martin Wirth, Jonathan Wiskandt, Kevin Wolf, Ludwig Worbes, Ethan Wright, Volker Wulfmeyer, Shanea Young, Chidong Zhang, Dongxiao Zhang, Florian Ziemen, Tobias Zinner, and Martin Zöger
Earth Syst. Sci. Data, 13, 4067–4119, https://doi.org/10.5194/essd-13-4067-2021, https://doi.org/10.5194/essd-13-4067-2021, 2021
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The EUREC4A field campaign, designed to test hypothesized mechanisms by which clouds respond to warming and benchmark next-generation Earth-system models, is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. It was the first campaign that attempted to characterize the full range of processes and scales influencing trade wind clouds.
Luca Possenti, Ingunn Skjelvan, Dariia Atamanchuk, Anders Tengberg, Matthew P. Humphreys, Socratis Loucaides, Liam Fernand, and Jan Kaiser
Ocean Sci., 17, 593–614, https://doi.org/10.5194/os-17-593-2021, https://doi.org/10.5194/os-17-593-2021, 2021
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A Seaglider was deployed for 8 months in the Norwegian Sea mounting an oxygen and, for the first time, a CO2 optode and a chlorophyll fluorescence sensor. The oxygen and CO2 data were used to assess the spatial and temporal variability and calculate the net community production, N(O2) and N(CT). The dataset was used to calculate net community production from inventory changes, air–sea flux, diapycnal mixing and entrainment.
Nicolai von Oppeln-Bronikowski, Brad de Young, Dariia Atamanchuk, and Douglas Wallace
Ocean Sci., 17, 1–16, https://doi.org/10.5194/os-17-1-2021, https://doi.org/10.5194/os-17-1-2021, 2021
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This paper describes challenges around the direct measurement of CO2 in the ocean using ocean gliders. We discuss our method of using multiple sensor platforms as test beds to carry out observing experiments and highlight the implications of our study for future glider missions. We also show high-resolution measurements and discuss challenges and lessons learned in the context of future ocean gas measurements.
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Short summary
In this study, we investigate oxygen variability in the deep western boundary current in the Labrador Sea from multiyear moored records. We estimate that about half of the oxygen taken up in the interior Labrador Sea by air–sea gas exchange during deep water formation is exported southward the same year. Our results underline the complexity of the oxygen uptake and export in the Labrador Sea and highlight the important role this region plays in supplying oxygen to the deep ocean.
In this study, we investigate oxygen variability in the deep western boundary current in the...
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