Articles | Volume 17, issue 1
https://doi.org/10.5194/os-17-265-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-17-265-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
10 Feb 2021
Research article |
| 10 Feb 2021
| 10 Feb 2021
Seasonal variability of the Atlantic Meridional Overturning Circulation at 11° S inferred from bottom pressure measurements
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Peter Brandt
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Kiel University, Kiel, Germany
Torsten Kanzow
Alfred Wegener Institute, Bremerhaven, Germany
Rebecca Hummels
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Moacyr Araujo
Department of Oceanography, Federal University of Pernambuco, Recife,
Brazil
Jonathan V. Durgadoo
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Kiel University, Kiel, Germany
Related authors
No articles found.
Linus Shihora, Torge Martin, Anna Christina Hans, Rebecca Hummels, Michael Schindelegger, and Henryk Dobslaw
EGUsphere, https://doi.org/10.5194/egusphere-2024-3660, https://doi.org/10.5194/egusphere-2024-3660, 2024
Short summary
Short summary
The Atlantic Meridional Overturning Circulation (AMOC) is a major part of the ocean circulation. Satellite gravimetry missions, like GRACE, which measure changes in Earth's mass distribution, could help monitor changes in the AMOC by detecting variations in ocean bottom pressure. To help asses if future satellite missions could detect these changes, we use ocean model simulation data to assess their connection. Additionally, we create a synthetic dataset future satellite mission simulations.
Yawouvi Dodji Soviadan, Miriam Beck, Joelle Habib, Alberto Baudena, Laetitia Drago, Alexandre Accardo, Remi Laxenaire, Sabrina Speich, Peter Brandt, Rainer Kiko, and Lars Stemmann
EGUsphere, https://doi.org/10.5194/egusphere-2024-3302, https://doi.org/10.5194/egusphere-2024-3302, 2024
Short summary
Short summary
Key parameters representing the gravity flux in global models are the sinking speed and the vertical attenuation of the exported material. We calculate for the first time, these parameters in situ for 6 intermittent blooms followed by export events using high-resolution (3 days) time series of 0–1000 m depth profiles from imaging sensor mounted on an Argo float. We show that sinking speed depends not only on size but also on the morphology of the particles, density being an important property.
Joelle Habib, Lars Stemmann, Alexandre Accardo, Alberto Baudena, Franz Philip Tuchen, Peter Brandt, and Rainer Kiko
EGUsphere, https://doi.org/10.5194/egusphere-2024-3365, https://doi.org/10.5194/egusphere-2024-3365, 2024
Short summary
Short summary
This study investigates how carbon moves from the ocean surface to the depths in the equatorial Atlantic, contributing to long-term carbon storage. Using an Argo float equipped with a camera, we captured two periods with major carbon export events. By identifying particle types and their sinking behaviors, we found that smaller, compact particles are key drivers of carbon transport. Our findings underscore the value of using imaging tools on autonomous platforms in tracking carbon sequestration.
Léo C. Aroucha, Joke F. Lübbecke, Peter Brandt, Franziska U. Schwarzkopf, and Arne Biastoch
EGUsphere, https://doi.org/10.5194/egusphere-2024-3320, https://doi.org/10.5194/egusphere-2024-3320, 2024
Short summary
Short summary
The West African coastal region sustains highly productive fisheries and marine ecosystems influenced by sea surface temperature. We use oceanic models to show that the freshwater input from land to ocean strengthens a surface northward (southward) coastal current north (south) of the Congo river mouth, promoting a transfer of cooler (warmer) waters to north (south) of the Congo discharge location. We highlight the significant impact of river discharge on ocean temperatures and circulation.
Eike E. Köhn, Richard J. Greatbatch, Peter Brandt, and Martin Claus
Ocean Sci., 20, 1281–1290, https://doi.org/10.5194/os-20-1281-2024, https://doi.org/10.5194/os-20-1281-2024, 2024
Short summary
Short summary
The latitudinally alternating zonal jets are a ubiquitous feature of the ocean. We use a simple model to illustrate the potential role of these jets in the formation, maintenance, and multidecadal variability in the oxygen minimum zones, using the eastern tropical North Atlantic oxygen minimum zone as an example.
Fabius Kouogang, Ariane Koch-Larrouy, Jorge Magalhaes, Alex Costa da Silva, Daphne Kerhervé, Arnaud Bertrand, Evan Cervelli, Jean-François Ternon, Pierre Rousselot, James Lee, Marcelo Rollnic, and Moacyr Araujo
EGUsphere, https://doi.org/10.5194/egusphere-2024-2548, https://doi.org/10.5194/egusphere-2024-2548, 2024
Short summary
Short summary
The first time direct measurements of turbulent dissipation from AMAZOMIX revealed high energy dissipations within [10-6,10-4] W.kg-1 caused at 65 % apart from internal tides in their generation zone, and [10-8,10-7] W.kg-1 caused at 50.4 % by mean circulation of surrounding water masses far fields. Finally, estimates of nutrient fluxes showed a very high flux of nitrate ([10-2, 10-0] mmol N m-2.s-1) and phosphate ([10-3, 10-1] mmol P m-2.s-1), due to both processes in Amazon region.
Ole Pinner, Friederike Pollmann, Markus Janout, Gunnar Voet, and Torsten Kanzow
EGUsphere, https://doi.org/10.5194/egusphere-2024-2444, https://doi.org/10.5194/egusphere-2024-2444, 2024
Short summary
Short summary
The Weddell Sea Bottom Water gravity current transports dense water from the continental shelf to the deep sea and is crucial for the formation of new deep sea water. Build on vertical profiles and time series measured in the northwestern Weddell Sea, we apply 3 methods to distinguish turbulence caused by internal waves from turbulence by other sources. We find that in the upper part of the gravity current, internal waves are important for the mixing of less dense water down into the current.
Swantje Bastin, Aleksei Koldunov, Florian Schütte, Oliver Gutjahr, Marta Agnieszka Mrozowska, Tim Fischer, Radomyra Shevchenko, Arjun Kumar, Nikolay Koldunov, Helmuth Haak, Nils Brüggemann, Rebecca Hummels, Mia Sophie Specht, Johann Jungclaus, Sergey Danilov, Marcus Dengler, and Markus Jochum
EGUsphere, https://doi.org/10.5194/egusphere-2024-2281, https://doi.org/10.5194/egusphere-2024-2281, 2024
Short summary
Short summary
Vertical mixing is an important process e.g. for tropical sea surface temperature, but cannot be resolved by ocean models. Comparisons of mixing schemes and settings have usually been done with a single model, sometimes yielding conflicting results. We systematically compare two widely used schemes, TKE and KPP, with different parameter settings, in two different ocean models, and show that most effects from mixing scheme parameter changes are model dependent.
Torsten Kanzow, Angelika Humbert, Thomas Mölg, Mirko Scheinert, Matthias Braun, Hans Burchard, Francesca Doglioni, Philipp Hochreuther, Martin Horwath, Oliver Huhn, Jürgen Kusche, Erik Loebel, Katrina Lutz, Ben Marzeion, Rebecca McPherson, Mahdi Mohammadi-Aragh, Marco Möller, Carolyne Pickler, Markus Reinert, Monika Rhein, Martin Rückamp, Janin Schaffer, Muhammad Shafeeque, Sophie Stolzenberger, Ralph Timmermann, Jenny Turton, Claudia Wekerle, and Ole Zeising
EGUsphere, https://doi.org/10.5194/egusphere-2024-757, https://doi.org/10.5194/egusphere-2024-757, 2024
Short summary
Short summary
The Greenland Ice Sheet represents the second-largest contributor to global sea-level rise. We quantify atmosphere, ice and ocean-based processes related to the mass balance of glaciers in Northeast Greenland, focusing on Greenland’s largest floating ice tongue, the 79N Glacier. We find that together, the different in situ and remote sensing observations and model simulations to reveal a consistent picture of a coupled atmosphere-ice sheet-ocean system, that has entered a phase of major change.
Kristin Burmeister, Franziska U. Schwarzkopf, Willi Rath, Arne Biastoch, Peter Brandt, Joke F. Lübbecke, and Mark Inall
Ocean Sci., 20, 307–339, https://doi.org/10.5194/os-20-307-2024, https://doi.org/10.5194/os-20-307-2024, 2024
Short summary
Short summary
We apply two different forcing products to a high-resolution ocean model to investigate their impact on the simulated upper-current field in the tropical Atlantic. Where possible, we compare the simulated results to long-term observations. We find large discrepancies between the two simulations regarding the wind and current fields. We propose that long-term observations, once they have reached a critical length, need to be used to test the quality of wind-driven simulations.
Lukrecia Stulic, Ralph Timmermann, Stephan Paul, Rolf Zentek, Günther Heinemann, and Torsten Kanzow
Ocean Sci., 19, 1791–1808, https://doi.org/10.5194/os-19-1791-2023, https://doi.org/10.5194/os-19-1791-2023, 2023
Short summary
Short summary
In the southern Weddell Sea, the strong sea ice growth in coastal polynyas drives formation of dense shelf water. By using a sea ice–ice shelf–ocean model with representation of the changing icescape based on satellite data, we find that polynya sea ice growth depends on both the regional atmospheric forcing and the icescape. Not just strength but also location of the sea ice growth in polynyas affects properties of the dense shelf water and the basal melting of the Filchner–Ronne Ice Shelf.
Swantje Bastin, Martin Claus, Richard J. Greatbatch, and Peter Brandt
Ocean Sci., 19, 923–939, https://doi.org/10.5194/os-19-923-2023, https://doi.org/10.5194/os-19-923-2023, 2023
Short summary
Short summary
Equatorial deep jets are ocean currents that flow along the Equator in the deep oceans. They are relevant for oxygen transport and tropical surface climate, but their dynamics are not yet entirely understood. We investigate different factors leading to the jets being broader than theory predicts. Mainly using an ocean model, but corroborating the results with shipboard observations, we show that loss of momentum is the main factor for the broadening but that meandering also contributes.
Peter Brandt, Gaël Alory, Founi Mesmin Awo, Marcus Dengler, Sandrine Djakouré, Rodrigue Anicet Imbol Koungue, Julien Jouanno, Mareike Körner, Marisa Roch, and Mathieu Rouault
Ocean Sci., 19, 581–601, https://doi.org/10.5194/os-19-581-2023, https://doi.org/10.5194/os-19-581-2023, 2023
Short summary
Short summary
Tropical upwelling systems are among the most productive ecosystems globally. The tropical Atlantic upwelling undergoes a strong seasonal cycle that is forced by the wind. Local wind-driven upwelling and remote effects, particularly via the propagation of equatorial and coastal trapped waves, lead to an upward and downward movement of the nitracline. Turbulent mixing results in upward supply of nutrients. Here, we review the different physical processes responsible for biological productivity.
Djoirka Minto Dimoune, Florence Birol, Fabrice Hernandez, Fabien Léger, and Moacyr Araujo
Ocean Sci., 19, 251–268, https://doi.org/10.5194/os-19-251-2023, https://doi.org/10.5194/os-19-251-2023, 2023
Short summary
Short summary
Altimeter-derived currents are used here to revisit the seasonal and interannual variability of all surface currents involved in the western tropical Atlantic circulation. A new approach based on the calculation of the current strengths and core positions is used to investigate the relationship between the currents, the remote wind variability, and the tropical Atlantic modes. The results show relationships at the seasonal and interannual timescale depending on the location of the currents.
Mareike Körner, Peter Brandt, and Marcus Dengler
Ocean Sci., 19, 121–139, https://doi.org/10.5194/os-19-121-2023, https://doi.org/10.5194/os-19-121-2023, 2023
Short summary
Short summary
The coastal waters off Angola host a productive ecosystem. Surface waters at the coast are colder than further offshore. We find that surface heat fluxes warm the coastal region more strongly than the offshore region and cannot explain the differences. The influence of horizontal heat advection is minor on the surface temperature change. In contrast, ocean turbulence data suggest that cooling associated with vertical mixing is an important mechanism to explain the near-coastal cooling.
Francesca Doglioni, Robert Ricker, Benjamin Rabe, Alexander Barth, Charles Troupin, and Torsten Kanzow
Earth Syst. Sci. Data, 15, 225–263, https://doi.org/10.5194/essd-15-225-2023, https://doi.org/10.5194/essd-15-225-2023, 2023
Short summary
Short summary
This paper presents a new satellite-derived gridded dataset, including 10 years of sea surface height and geostrophic velocity at monthly resolution, over the Arctic ice-covered and ice-free regions, up to 88° N. We assess the dataset by comparison to independent satellite and mooring data. Results correlate well with independent satellite data at monthly timescales, and the geostrophic velocity fields can resolve seasonal to interannual variability of boundary currents wider than about 50 km.
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
Short summary
Short summary
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.
Gilles Reverdin, Claire Waelbroeck, Catherine Pierre, Camille Akhoudas, Giovanni Aloisi, Marion Benetti, Bernard Bourlès, Magnus Danielsen, Jérôme Demange, Denis Diverrès, Jean-Claude Gascard, Marie-Noëlle Houssais, Hervé Le Goff, Pascale Lherminier, Claire Lo Monaco, Herlé Mercier, Nicolas Metzl, Simon Morisset, Aïcha Naamar, Thierry Reynaud, Jean-Baptiste Sallée, Virginie Thierry, Susan E. Hartman, Edward W. Mawji, Solveig Olafsdottir, Torsten Kanzow, Anton Velo, Antje Voelker, Igor Yashayaev, F. Alexander Haumann, Melanie J. Leng, Carol Arrowsmith, and Michael Meredith
Earth Syst. Sci. Data, 14, 2721–2735, https://doi.org/10.5194/essd-14-2721-2022, https://doi.org/10.5194/essd-14-2721-2022, 2022
Short summary
Short summary
The CISE-LOCEAN seawater stable isotope dataset has close to 8000 data entries. The δ18O and δD isotopic data measured at LOCEAN have uncertainties of at most 0.05 ‰ and 0.25 ‰, respectively. Some data were adjusted to correct for evaporation. The internal consistency indicates that the data can be used to investigate time and space variability to within 0.03 ‰ and 0.15 ‰ in δ18O–δD17; comparisons with data analyzed in other institutions suggest larger differences with other datasets.
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
Short summary
Short summary
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.
Francesca Doglioni, Robert Ricker, Benjamin Rabe, and Torsten Kanzow
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2021-170, https://doi.org/10.5194/essd-2021-170, 2021
Manuscript not accepted for further review
Short summary
Short summary
This paper presents a new satellite-derived gridded dataset of sea surface height and geostrophic velocity, over the Arctic ice-covered and ice-free regions up to 88° N. The dataset includes velocities north of 82° N, which were not available before. We assess the dataset by comparison to one independent satellite dataset and to independent mooring data. Results show that the geostrophic velocity fields can resolve seasonal to interannual variability of boundary currents wider than about 50 km.
Josefine Maas, Susann Tegtmeier, Yue Jia, Birgit Quack, Jonathan V. Durgadoo, and Arne Biastoch
Atmos. Chem. Phys., 21, 4103–4121, https://doi.org/10.5194/acp-21-4103-2021, https://doi.org/10.5194/acp-21-4103-2021, 2021
Short summary
Short summary
Cooling-water disinfection at coastal power plants is a known source of atmospheric bromoform. A large source of anthropogenic bromoform is the industrial regions in East Asia. In current bottom-up flux estimates, these anthropogenic emissions are missing, underestimating the global air–sea flux of bromoform. With transport simulations, we show that by including anthropogenic bromoform from cooling-water treatment, the bottom-up flux estimates significantly improve in East and Southeast Asia.
Franziska U. Schwarzkopf, Arne Biastoch, Claus W. Böning, Jérôme Chanut, Jonathan V. Durgadoo, Klaus Getzlaff, Jan Harlaß, Jan K. Rieck, Christina Roth, Markus M. Scheinert, and René Schubert
Geosci. Model Dev., 12, 3329–3355, https://doi.org/10.5194/gmd-12-3329-2019, https://doi.org/10.5194/gmd-12-3329-2019, 2019
Short summary
Short summary
A family of nested global ocean general circulation model configurations, the INALT family, has been established with resolutions of 1/10°, 1/20° and 1/60° in the South Atlantic and western Indian oceans, covering the greater Agulhas Current (AC) system. The INALT family provides a consistent set of configurations that allows to address eddy dynamics in the AC system and their impact on the large-scale ocean circulation.
Josefine Maas, Susann Tegtmeier, Birgit Quack, Arne Biastoch, Jonathan V. Durgadoo, Siren Rühs, Stephan Gollasch, and Matej David
Ocean Sci., 15, 891–904, https://doi.org/10.5194/os-15-891-2019, https://doi.org/10.5194/os-15-891-2019, 2019
Short summary
Short summary
In a large-scale analysis, the spread of disinfection by-products from oxidative ballast water treatment is investigated, with a focus on Southeast Asia where major ports are located. Halogenated compounds such as bromoform (CHBr3) are produced in the ballast water and, once emitted into the environment, can participate in ozone depletion. Anthropogenic bromoform is rapidly emitted into the atmosphere and can locally double around large ports. A large-scale impact cannot be found.
Tim Fischer, Annette Kock, Damian L. Arévalo-Martínez, Marcus Dengler, Peter Brandt, and Hermann W. Bange
Biogeosciences, 16, 2307–2328, https://doi.org/10.5194/bg-16-2307-2019, https://doi.org/10.5194/bg-16-2307-2019, 2019
Short summary
Short summary
We investigated air–sea gas exchange in oceanic upwelling regions for the case of nitrous oxide off Peru. In this region, routine concentration measurements from ships at 5 m or 10 m depth prove to overestimate surface (bulk) concentration. Thus, standard estimates of gas exchange will show systematic error. This is due to very shallow stratified layers that inhibit exchange between surface water and waters below and can exist for several days. Maximum bias occurs in moderate wind conditions.
Yao Fu, Johannes Karstensen, and Peter Brandt
Ocean Sci., 14, 589–616, https://doi.org/10.5194/os-14-589-2018, https://doi.org/10.5194/os-14-589-2018, 2018
Short summary
Short summary
Hydrographic analysis in the Atlantic along 14.5° N and 24.5° N shows that between the periods of 1989/92 and 2013/15, the Antarctic Intermediate Water became warmer and saltier at 14.5° N, and that the Antarctic Bottom Water became lighter at both latitudes. By applying a box inverse model, the Atlantic Meridional Overturning Circulation (AMOC) was determined. Comparison among the inverse solution, GECCO2, RAPID, and MOVE shows that the AMOC has not significantly changed in the past 20 years.
Fabrice Ardhuin, Yevgueny Aksenov, Alvise Benetazzo, Laurent Bertino, Peter Brandt, Eric Caubet, Bertrand Chapron, Fabrice Collard, Sophie Cravatte, Jean-Marc Delouis, Frederic Dias, Gérald Dibarboure, Lucile Gaultier, Johnny Johannessen, Anton Korosov, Georgy Manucharyan, Dimitris Menemenlis, Melisa Menendez, Goulven Monnier, Alexis Mouche, Frédéric Nouguier, George Nurser, Pierre Rampal, Ad Reniers, Ernesto Rodriguez, Justin Stopa, Céline Tison, Clément Ubelmann, Erik van Sebille, and Jiping Xie
Ocean Sci., 14, 337–354, https://doi.org/10.5194/os-14-337-2018, https://doi.org/10.5194/os-14-337-2018, 2018
Short summary
Short summary
The Sea surface KInematics Multiscale (SKIM) monitoring mission is a proposal for a future satellite that is designed to measure ocean currents and waves. Using a Doppler radar, the accurate measurement of currents requires the removal of the mean velocity due to ocean wave motions. This paper describes the main processing steps needed to produce currents and wave data from the radar measurements. With this technique, SKIM can provide unprecedented coverage and resolution, over the global ocean.
Eike E. Köhn, Sören Thomsen, Damian L. Arévalo-Martínez, and Torsten Kanzow
Ocean Sci., 13, 1017–1033, https://doi.org/10.5194/os-13-1017-2017, https://doi.org/10.5194/os-13-1017-2017, 2017
Sandrine Djakouré, Moacyr Araujo, Aubains Hounsou-Gbo, Carlos Noriega, and Bernard Bourlès
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-346, https://doi.org/10.5194/bg-2017-346, 2017
Revised manuscript has not been submitted
Yao Fu, Johannes Karstensen, and Peter Brandt
Ocean Sci., 13, 531–549, https://doi.org/10.5194/os-13-531-2017, https://doi.org/10.5194/os-13-531-2017, 2017
Short summary
Short summary
Meridional Ekman transport in the tropical Atlantic was estimated directly by using observed ageostrophic velocity, and indirectly by using wind stress data. The direct and indirect methods agree well with each other. The top of the pycnocline represents the Ekman depth better than the mixed layer depth and a constant depth. The Ekman heat and salt fluxes calculated from sea surface temperature and salinity or from high-resolution temperature and salinity profile data differ only marginally.
Johannes Hahn, Peter Brandt, Sunke Schmidtko, and Gerd Krahmann
Ocean Sci., 13, 551–576, https://doi.org/10.5194/os-13-551-2017, https://doi.org/10.5194/os-13-551-2017, 2017
Short summary
Short summary
Recent studies have shown that the eastern tropical North Atlantic is subject to a strong decrease of the oceanic oxygen concentration in the upper 1000 m from the 1960s to today. By analyzing a broad observational data set, this study found an even stronger oxygen decrease in the upper 400 m throughout the past decade, whereas oxygen increase was found below (400–1000 m). Changes in the strength of the zonal currents are the most likely reason for the observed decadal oxygen changes.
Amelie Driemel, Eberhard Fahrbach, Gerd Rohardt, Agnieszka Beszczynska-Möller, Antje Boetius, Gereon Budéus, Boris Cisewski, Ralph Engbrodt, Steffen Gauger, Walter Geibert, Patrizia Geprägs, Dieter Gerdes, Rainer Gersonde, Arnold L. Gordon, Hannes Grobe, Hartmut H. Hellmer, Enrique Isla, Stanley S. Jacobs, Markus Janout, Wilfried Jokat, Michael Klages, Gerhard Kuhn, Jens Meincke, Sven Ober, Svein Østerhus, Ray G. Peterson, Benjamin Rabe, Bert Rudels, Ursula Schauer, Michael Schröder, Stefanie Schumacher, Rainer Sieger, Jüri Sildam, Thomas Soltwedel, Elena Stangeew, Manfred Stein, Volker H Strass, Jörn Thiede, Sandra Tippenhauer, Cornelis Veth, Wilken-Jon von Appen, Marie-France Weirig, Andreas Wisotzki, Dieter A. Wolf-Gladrow, and Torsten Kanzow
Earth Syst. Sci. Data, 9, 211–220, https://doi.org/10.5194/essd-9-211-2017, https://doi.org/10.5194/essd-9-211-2017, 2017
Short summary
Short summary
Our oceans are always in motion – huge water masses are circulated by winds and by global seawater density gradients resulting from different water temperatures and salinities. Measuring temperature and salinity of the world's oceans is crucial e.g. to understand our climate. Since 1983, the research icebreaker Polarstern has been the basis of numerous water profile measurements in the Arctic and the Antarctic. We report on a unique collection of 33 years of polar salinity and temperature data.
Florian Schütte, Johannes Karstensen, Gerd Krahmann, Helena Hauss, Björn Fiedler, Peter Brandt, Martin Visbeck, and Arne Körtzinger
Biogeosciences, 13, 5865–5881, https://doi.org/10.5194/bg-13-5865-2016, https://doi.org/10.5194/bg-13-5865-2016, 2016
Short summary
Short summary
Mesoscale eddies with very low–oxygen concentrations at shallow depth have been recently discovered in the eastern tropical North Atlantic. Our analysis shows that low oxygen eddies occur more frequent than expected and are found even close to the equator (8° N). From budget calculations we show that an oxygen reduction of 7 µmol/kg in the depth range of 50–150 m in the eastern tropical North Atlantic (peak reduction is 16 µmol/kg at 100 m depth) can be associated with the dispersion of these eddies.
Florian Schütte, Peter Brandt, and Johannes Karstensen
Ocean Sci., 12, 663–685, https://doi.org/10.5194/os-12-663-2016, https://doi.org/10.5194/os-12-663-2016, 2016
Short summary
Short summary
We want to examine the characteristics of mesoscale eddies in the tropical northeastern Atlantic. They serve as transport agents, exporting water from the coast into the open ocean. Traditionally eddies are categorized with respect to their rotation: cyclonic and anticyclonic. But we could identify, with a combination of different satellite products, a third type called "anticyclonic mode-water eddy" transporting much larger anomalies. We propose a distinction into three classes for further studies.
K. A. Reeve, O. Boebel, T. Kanzow, V. Strass, G. Rohardt, and E. Fahrbach
Earth Syst. Sci. Data, 8, 15–40, https://doi.org/10.5194/essd-8-15-2016, https://doi.org/10.5194/essd-8-15-2016, 2016
Short summary
Short summary
We present spatially gridded, time-composite mapped data of temperature and salinity of the upper 2000m of the Weddell Gyre through the objective mapping of Argo float data. This was realized on fixed-pressure surfaces ranging from 50 to 2000 dbar. Pressure, temperature and salinity are also available at the level of the sub-surface temperature maximum, which represents the core of Warm Deep Water, the primary heat source of the Weddell Gyre. A detailed description of the methods is provided.
L. Stramma, R. Czeschel, T. Tanhua, P. Brandt, M. Visbeck, and B. S. Giese
Ocean Sci., 12, 153–167, https://doi.org/10.5194/os-12-153-2016, https://doi.org/10.5194/os-12-153-2016, 2016
Short summary
Short summary
The subsurface circulation in the eastern tropical North Atlantic OMZ is derived from velocity, float and tracer data and data assimilation results, and shows a cyclonic flow around the Guinea Dome reaching into the oxygen minimum zone. The stronger cyclonic flow around the Guinea Dome in 2009 seem to be connected to a strong Atlantic Meridional Mode (AMM) event.
A continuous deoxygenation trend of the low oxygen layer was confirmed.
Eddy influence is weak south of the Cape Verde Islands.
J. Karstensen, B. Fiedler, F. Schütte, P. Brandt, A. Körtzinger, G. Fischer, R. Zantopp, J. Hahn, M. Visbeck, and D. Wallace
Biogeosciences, 12, 2597–2605, https://doi.org/10.5194/bg-12-2597-2015, https://doi.org/10.5194/bg-12-2597-2015, 2015
Short summary
Short summary
This study is the first report of the formation of dead zones in the open ocean. A combination of multiple ocean observing system elements (mooring, floats, satellites, ships) allowed us to reconstruct the generation of the dead zones and to connect the formation to enhanced respiration within mesoscale ocean eddies. The dead zones present specific threats to the ecosystem, such as the interruption of the diurnal migration of zooplankters.
P. Brandt, H. W. Bange, D. Banyte, M. Dengler, S.-H. Didwischus, T. Fischer, R. J. Greatbatch, J. Hahn, T. Kanzow, J. Karstensen, A. Körtzinger, G. Krahmann, S. Schmidtko, L. Stramma, T. Tanhua, and M. Visbeck
Biogeosciences, 12, 489–512, https://doi.org/10.5194/bg-12-489-2015, https://doi.org/10.5194/bg-12-489-2015, 2015
Short summary
Short summary
Our observational study looks at the structure of the eastern tropical North Atlantic (ETNA) oxygen minimum zone (OMZ) in comparison with the less-ventilated, eastern tropical South Pacific OMZ. We quantify the OMZ’s oxygen budget composed of consumption, advection, lateral and vertical mixing. Substantial oxygen variability is observed on interannual to multidecadal timescales. The deoxygenation of the ETNA OMZ during the last decades represents a substantial imbalance of the oxygen budget.
T. Fischer, D. Banyte, P. Brandt, M. Dengler, G. Krahmann, T. Tanhua, and M. Visbeck
Biogeosciences, 10, 5079–5093, https://doi.org/10.5194/bg-10-5079-2013, https://doi.org/10.5194/bg-10-5079-2013, 2013
Cited articles
Bachèlery, M.-L., Illig, S., and Dadou, I.: Interannual variability in
the South-East Atlantic Ocean, focusing on the Benguela Upwelling System:
Remote versus local forcing, J. Geophys. Res.-Oceans, 121, 284–310,
https://doi.org/10.1002/2015JC011168, 2016.
Bentamy, A. and Croizé-Fillon, D.: Gridded surface wind fields from
Metop/ASCAT measurements, Int. J. Remote Sens., 33, 1729–1754. https://doi.org/10.1080/01431161.2011.600348, 2012.
Biastoch, A., Böning, C. W., and Lutjeharms, J. R. E.: Agulhas leakage
dynamics affects decadal variability in Atlantic overturning circulation,
Nature, 456, 489–492, https://doi.org/10.1038/nature07426, 2008.
Bingham, R. J. and Hughes, C. W.: The relationship between sea‐level and bottom pressure variability in an eddy permitting ocean model, Geophys. Res. Lett., 35, L03602, https://doi.org/10.1029/2007GL032662, 2008.
Boebel, O., Schmid, C., and Zenk, W.: Kinematic elements of Antarctic Intermediate Water in the
western South Atlantic, Deep-Sea Res. Pt. II, 46, 355–392, https://doi.org/10.1016/S0967-0645(98)00104-0, 1999.
Brandt, P., Claus, M., Greatbatch, R. J., Kopte, R., Toole, J. M., Johns, W.
E., and Böning, C. W.: Annual and semiannual cycle of equatorial
Atlantic circulation associated with basin mode resonance. J. Phys.
Oceanogr., 46, 3011–3029, https://doi.org/10.1175/JPO-D-15-0248.1, 2016.
Buckley, M. W. and Marshall, J.: Observations, inferences, and mechanisms of
the Atlantic Meridional Overturning Circulation: A review, Rev. Geophys.,
54, 5–63, https://doi.org/10.1002/2015RG000493, 2016.
Chidichimo, M. P., Kanzow, T., Cunningham, S. A., Johns, W. E., and Marotzke, J.: The contribution of eastern-boundary density variations to the Atlantic meridional overturning circulation at 26.5∘ N, Ocean Sci., 6, 475–490, https://doi.org/10.5194/os-6-475-2010, 2010.
Chu, P. C., Ivanov, L. M., Melnichenko, O. V., and Wells, N. C.: On long
baroclinic Rossby waves in the tropical North Atlantic observed from
profiling floats, J. Geophys. Res., 112, C05032, https://doi.org/10.1029/2006JC003698,
2007.
Codiga, D. L.: Unified Tidal Analysis and Prediction Using the UTide Matlab
Functions, Technical Report 2011-01, Graduate School of Oceanography,
University of Rhode Island, Narragansett, RI. 59 pp., available at:
ftp://www.po.gso.uri.edu/pub/downloads/codiga/pubs/2011Codiga-UTide-Report.pdf (latest access: 15 August 2019),
2011.
Cunningham, S. A., Kanzow, T., Rayner, D., Baringer, M. O., Johns, W. E.,
Marotzke, J., Longworth, H. R., Grant, E. M., Hirschi, J. J.-M., Beal, L.
M., Meinen, C. S., and Bryden, H. L.: Temporal variability of the Atlantic
meridional overturning circulation at 26.5∘ N, Science, 317,
935–938, https://doi.org/10.1126/science.1141304, 2007.
Cunningham, S. A.: RRS Discovery Cruise D334, 27 Oct-24 Nov 2008, RAPID
Mooring Cruise Report, 2009.
da Silveira, I. C. A., Miranda, L. B., and Brown, W. S.: On the origins of
the North Brazil Current, J. Geophys. Res., 99, 22501–22512,
https://doi.org/10.1029/94JC01776, 1994.
Dengler, M., Schott, F. A., Eden, C., Brandt, P., Fischer, J., and Zantopp,
R. J.: Break-up of the Atlantic deep western boundary current into eddies at
8 degrees S, Nature, 432, 1018–1020, https://doi.org/10.1038/nature03134, 2004.
Donohue, K. A., Watts, D. R., Tracey, K. L., Greene, A. D., and Kennelly,
M.: Mapping circulation in the Kuroshio Extension with an array of current
and pressure recording inverted echo sounders, J. Atmos. Ocean. Technol., 27, 507–527,
https://doi.org/10.1175/2009JTECHO686.1, 2010.
Döös, K.: Influence of the Rossby waves on the seasonal cycle in the
tropical Atlantic, J. Geophys. Res., 104, 29591–29598,
https://doi.org/10.1029/1999JC900126, 1999.
Drakkar Group: DRAKKAR: developing high resolution ocean components for European Earth system models, Clivar Exchanges, 65, 18–21, 2014.
Durgadoo, J. V., Loveday, B. R., Reason, C. J. C., Penven, P., and Biastoch,
A.: Agulhas leakage predominantly responds to the Southern Hemisphere
westerlies, J. Phys. Oceanogr., 43, 2113–2131,
https://doi.org/10.1175/JPO-D-13-047.1, 2013.
Frajka-Williams, E., Lankhorst, M., Koelling, J., and Send, U.: Coherent
circulation changes in the Deep North Atlantic from 16∘ N and
26∘ N transport arrays. J. Geophys. Res., 123, 3427-3443, https://doi.org/10.1029/2018JC013949, 2018.
Frajka-Williams, E., Ansorge, I. J, Baehr, J., Bryden, H. L.,
Chidichimo, M. P., Cunningham, S. A., Danabasoglu, G., Dong, S., Donohue, K. A., Elipot, S., Heimbach, P., Holliday, N., P., Hummels, R., Jackson, L., C., Karstensen, J., Lankhorst, M., Le Bras, I. A., Lozier, M. S., McDonagh, E. L., Meinen, C. S., Mercier, H., Moat, B. I., Perez, R. C., Piecuch, C. G., Rhein, M., Srokosz, M. A., Trenberth, K. E., Bacon, S., Forget, G., Goni, G., Kieke, D., Koelling, J., Lamont, T., McCarthy, G. D., Mertens, C., Send, U., Smeed, D. A., Speich, S., van den Berg, M., Volkov, D., and Wilson, C.: Atlantic Meridional Overturning Circulation: Observed transport and variability, Front. Mar. Sci., 6, 260, https://doi.org/10.3389/fmars.2019.00260, 2019.
Hansen, B., Húsgarð Larsen, K. M., Hátún, H., and Østerhus, S.: A stable Faroe Bank Channel overflow 1995–2015, Ocean Sci., 12, 1205–1220, https://doi.org/10.5194/os-12-1205-2016, 2016.
Herrford, J., Brandt, P., and Zenk, W.: Property Changes of Deep and Bottom
Waters in the western tropical Atlantic, Deep-Sea Res. Pt. I, 124, 103–125,
https://doi.org/10.1016/j.dsr.2017.04.007, 2017.
Herrford, J., Brandt, P., and Krahmann, G.: Estimating seasonal AMOC variability at 11∘ S using Bottom Pressure Recorders (2013–2018), PANGAEA, https://doi.org/10.1594/PANGAEA.907589, 2019.
Hirschi, J., Baehr, J., Marotzke, J., Stark J., Cunningham, S., and
Beismann, J.-O.: A monitoring design for the Atlantic meridional overturning
circulation, Geophys. Res. Lett., 30, 1413, https://doi.org/10.1029/2002GL016776, 2003.
Hirschi, J. J., Killworth, P. D., and Blundell, J. R.: Subannual, Seasonal, and Interannual Variability of the North Atlantic Meridional Overturning
Circulation. J. Phys. Oceanogr., 37, 1246–1265, https://doi.org/10.1175/JPO3049.1,
2006.
Hummels, R., Brandt, P., Dengler, M., Fischer, J., Araujo, M., Veleda, D.,
and Durgadoo, J. V.: Interannual to decadal changes in the western boundary
circulation in the Atlantic at 11∘ S, Geophys. Res. Lett., 42, 7615–7622,
https://doi.org/10.1002/2015GL065254, 2015.
Illig, S., Dewitte, B., Ayoub, N., du Penhoat, Y., Reverdin, G., De Mey, P., Bonjean, F., and Lagerloef, G. S. E.: nterannual long equatorial waves in the tropical Atlantic from a high‐resolution ocean general circulation model experiment in 1981–2000, J. Geophys. Res., 109, C02022, https://doi.org/10.1029/2003JC001771, 2004.
Illig, S., Bachèlery, M.-L., and Cadier, E.: Subseasonal coastal-trapped
wave propagations in the southeastern Pacific and Atlantic Oceans: 2. Wave
characteristics and connection with the equatorial variability. J. Geophys.
Res., 123, 3942–3961, https://doi.org/10.1029/2017JC013540, 2018.
Imbol Koungue, R. A., Illig, S., and Rouault, M.: Role of interannual Kelvin
wave propagations in the equatorial Atlantic on the Angola Benguela Current
system. J. Geophys. Res.-Oceans, 122, 4685–4703,
https://doi.org/10.1002/2016JC012463, 2017.
Jochumsen, K., Moritz, M., Nunes, N., Quadfasel, D., Larsen, K. M. H.,
Hansen, B., Valdimarsson, H., and Jonsson, S.: Revised transport estimates
of the Denmark Strait overflow, J. Geophys. Res.-Oceans, 122, 3434–3450,
https://doi.org/10.1002/2017JC012803, 2017.
Johns, W. E., Kanzow, T., and Zantopp, R.: Estimating ocean transports with
dynamic height moorings: An application in the Atlantic Deep Western
Boundary Current at 26∘ N, Deep-Sea Res. Pt. I, 52, 1542–1567.
https://doi.org/10.1016/j.dsr.2005.02.002, 2005.
Johns, W. E., Baringer, M. O., Beal, L. M., Cunningham, S. A., Kanzow, T.,
Bryden, H. L., Hirschi, J. J., Marotzke, J., Meinen, C. S., Shaw, B., and
Curry, R.: Continuous, Array-Based Estimates of Atlantic Ocean Heat
Transport at 26.5∘ N, J. Climate, 24, 2429–2449,
https://doi.org/10.1175/2010JCLI3997.1, 2011.
Kajikawa, H. and Kobata, T.: Reproducibility of calibration results by
0-A-0 pressurization procedures for hydraulic pressure transducers, Meas.
Sci. Technol., 5, 015008, https://doi.org/10.1088/0957-0233/25/1/015008, 2014.
Kanzow, T., Send, U., Zenk, W., Chave, A. D., and Rhein, M.: Monitoring the
integrated deep meridional flow in the tropical North Atlantic: long-term
performance of a geostrophic array, Deep-Sea Res. Pt. I, 53, 528–546,
https://doi.org/10.1016/j.dsr.2005.12.007, 2006.
Kanzow, T., Cunningham, S. A., Rayner, D., Hirschi, J. J.-M, Johns, W. E.,
Baringer, M. O., Bryden, H. L., Beal, L. M., Meinen, C. S., and Marotzke,
J.: Observed flow compensation associated with the MOC at 26.5∘ N in the Atlantic, Science, 317, 938–941, https://doi.org/10.1126/science.1141293, 2007.
Kanzow, T., Send, U., and McCartney, M.: On the variability of the deep
meridional transports in the tropical North Atlantic, Deep-Sea Res. Pt. I, 55, 1601–1623, https://doi.org/10.1016/j.dsr.2008.07.011, 2008.
Kanzow, T., Cunningham, S. A., Johns, W. E., Hirschi, J. J., Marotzke, J.,
Baringer, M. O., Meinen, C. S., Chidichimo, M. P., Atkinson, C., Beal, L.
M., Bryden, H. L., and Collins, J.: Seasonal Variability of the Atlantic
Meridional Overturning Circulation at 26.5∘ N, J. Climate, 23,
5678–5698, https://doi.org/10.1175/2010JCLI3389, 2010.
Kersalé, M., Meinen, C. S., Perez, R. C., Le Henaff, M., Valla, D.,
Lamont, T., Sato, O. T., Dong, S., Terre, T., van Caspel, M. Chidichimo, M. P., van den Berg, M., Speich, S., Piola, A. R., Campos, E. J. D.,
Ansorge, I., Volkov, D. L., Lumpkin, R., and Garzoli, S.: Highly Variable Upper and Abyssal Overturning Cells in the South Atlantic, Sci. Adv., 6, eaba7573,
https://doi.org/10.1126/sciadv.aba7573, 2020.
Kolodziejczyk, N., Reverdin, G., Gaillard, F., and Lazar, A.: Low-frequency
thermohaline variability in the Subtropical South Atlantic pycnocline during
2002–2013, Geophys. Res. Lett., 41, 6468–6475, https://doi.org/10.1002/2014GL061160,
2014.
Kopte, R., Brandt, P., Dengler, M., Tchipalanga, P. C. M., Macuéria, M.,
and Ostrowski, M.: The Angola Current: Flow and hydrographic characteristics
as observed at 11∘ S, J. Geophys. Res. Oceans, 122, 1177–1189,
https://doi.org/10.1002/2016JC012374, 2017.
Kopte, R., Brandt, P., Claus, M., Greatbatch, R. J., and Dengler, M.: Role
of equatorial basin-mode resonance for the seasonal variability of the
Angola Current at 11∘ S, J. Phys. Oceanogr., 48, 261–281,
https://doi.org/10.1175/JPO-D-17-0111.1, 2018.
Large, W. G. and Yeager S. G.: The global climatology of an
interannually varying air-sea flux data set, Clim. Dyn., 33, 341–364,
https://doi.org/10.1007/s00382-008-0441-3, 2009.
Lavin, A., Bryden, H. L., and Parilla, G.: Meridional transport and heat
flux variations in the subtropical North Atlantic, Global Atmos. Ocean Sys.,
6, 269–293, 1998.
Le Bars, D., Durgadoo, J. V., Dijkstra, H. A., Biastoch, A., and De Ruijter, W. P. M.: An observed 20-year time series of Agulhas leakage, Ocean Sci., 10, 601–609, https://doi.org/10.5194/os-10-601-2014, 2014.
Lozier, M. S., Li, F., Bacon, S., Bahr, F., Bower, A. S., Cunningham, S. A.,
de Jong, M. F., de Steur, L., DeYoung, B., Fischer, J., Gary, S. F.,
Greenan, N. J. W., Holliday, N. P., Houk, A., Houpert, L., Inall, M. E.,
Johns, W. E., Johnson, H. L., Johnson, C., Karstensen, J., Koman, G.,
LeBras, I. A., Lin, X., Mackay, N., Marshall, D. P., Mercier, H., Oltmanns,
M., Pickart, R. S., Ramsey, A. L., Rayner, D., Straneo, F., Thierry, V.,
Torres, D. J., Williams, R. G., Wilson, C., Yang, J., Yashayaev, I., and
Zhao, J.: A Sea Change in Our View of Overturning in the Subpolar North
Atlantic, Science, 363, 516–521, https://doi.org/10.1126/science.aau6592, 2019.
Lübbecke, J. F., Durgadoo, J. V., and Biastoch, A.: Contribution of Increased Agulhas Leakage to
Tropical Atlantic Warming, J. Clim., 28, 9697–9706, https://doi.org/10.1175/JCLI-D-15-0258.1, 2015.
Lumpkin, R. and Speer, K.: Large-Scale Vertical and Horizontal Circulation
in the North Atlantic Ocean, J. Phys. Oceanogr., 33, 1902–1920,
https://doi.org/10.1175/1520-0485(2003)033<1902:LVAHCI>2.0.CO;2,
2003.
Lumpkin, R. and Speer, K.: Global ocean meridional overturning. J. Phys.
Oceanogr., 37, 2550–2562, https://doi.org/10.1175/JPO3130.1, 2007.
Madec, G.: NEMO ocean engine, Note du Pole de modelisation, No. 27. Inst.
Pierre-Simon Laplace (IPSL), France, 2008.
McCarthy, G. D., Smeed, D. A., Johns, W. E., Frajka-Williams, E., Moat, B.
I., Rayner, D., Baringer, M. O., Meinen, C. S., Collins, J., Bryden, H. L.:
Measuring the Atlantic meridional overturning circulation at 26∘ N, Prog. Oceanogr., 130, 91–111, https://doi.org/10.1016/j.pocean.2014.10.006, 2015.
Meinen, C. S., Johns, W. E., Garzoli, S. L., van Sebille, E., Rayner, D.,
Kanzow, T., and Baringer, M. O.: Variability of the Deep Western Boundary
Current at 26.5∘ N during 2004-2009, Deep-Sea Res. Pt. II, 85,
154–168, https://doi.org/10.1016/j.dsr2.2012.07.036, 2013.
Meinen, C. S., Speich, S., Piola, A. R., Ansorge, I., Campos, E.,
Kersalè, M., Terre, T., Chidichimo, M.-P., Lamont, T., Sato, O. T.,
Perez, R. C., Valla, D., van den Berg, M., Le Henaff, M., Dong, S., and
Garzoli, S. L.: Meridional Overturning Circulation transport variability at
34.5∘ S during 2009-2017: Baroclinic and barotropic flows and the
dueling influence of the boundaries, Geophys. Res. Lett., 45, 4180–4188,
https://doi.org/10.1029/2018GL077408, 2018.
Philander, S. G. H. and Pacanowski, R. C.: A model of the seasonal cycle in
the tropical Atlantic Ocean, J. Geophys. Res., 91, 14192–14206,
https://doi.org/10.1029/JC091iC12p14192, 1986.
Polo, I., Lazar, A., Rodriguez-Fonseca, B., and Arnault, S.: Oceanic Kelvin
waves and tropical Atlantic intraseasonal variability: 1. Kelvin wave
characterization, J. Geophys. Res., 113, C07009, https://doi.org/10.1029/2007JC004495,
2008.
Pujol, M.-I., Faugère, Y., Taburet, G., Dupuy, S., Pelloquin, C., Ablain, M., and Picot, N.: DUACS DT2014: the new multi-mission altimeter data set reprocessed over 20 years, Ocean Sci., 12, 1067–1090, https://doi.org/10.5194/os-12-1067-2016, 2016.
Richardson, P. L.: On the history of meridional overturning circulation
schematic diagrams, Prog. Oceanogr., 76, 466–486.
https://doi.org/10.1016/j.pocean.2008.01.005, 2008.
Rodrigues, R. R., Rothstein, L. M., and Wimbush, M.: Seasonal Variability of
the South Equatorial Current Bifurcation in the Atlantic Ocean: A Numerical
Study, J. Phys. Oceanogr., 37, 16–30, https://doi.org/10.1175/JPO2983.1, 2007.
Roessler, A., Rhein, M., Kieke, D., and Mertens, C.: Long-term observations
of North Atlantic Current transport at the gateway between western and
eastern Atlantic, J. Geophys. Res.-Oceans, 120, 4003–4027.
https://doi.org/10.1002/2014JC010662, 2015.
Rühs, S., Getzlaff, K., Durgadoo, J. V., Biastoch, A., and Böning, C.
W.: On the suitability of North Brazil current transport estimates for
monitoring basin-scale AMOC changes, Geophys. Res. Lett., 42, 8072–8080,
https://doi.org/10.1002/2015GL065695, 2015.
Schmidtko, S. and Johnson, G. C.: Multidecadal warming and shoaling of
Antarctic Intermediate Water, J. Clim., 25, 207–221,
https://doi.org/10.1175/JCLI-D-11-00021.1, 2012.
Schott, F. A., Dengler, M., Zantopp, R., Stramma, L., Fischer, J., and
Brandt, P.: The Shallow and Deep Western Boundary Circulation of the South
Atlantic at 5∘ –11∘ S, J. Phys. Oceanogr., 35, 2031–2053,
https://doi.org/10.1175/JPO2813.1, 2005.
Send, U., Lankhorst, M., and Kanzow, T.: Observation of decadal change in
the Atlantic meridional overturning circulation using 10 years of continuous
transport data, Geophys. Res. Lett., 38, L24606, https://doi.org/10.1029/2011GL049801, 2011.
Silva, M., Araujo, M., Servain, J., Penven, P., and Lentini, C. A. D.:
High-resolution regional ocean dynamics simulation in the southwestern
tropical Atlantic, Ocean Model., 30, 256–269,
https://doi.org/10.1016/j.ocemod.2009.07.002, 2009.
Srokosz, M. A. and Bryden, H. L.: Observing the Atlantic meridional
overturning circulation yields a decade of inevitable surprises, Science
348, 1255575, https://doi.org/10.1126/science.1255575, 2015.
Stramma, L. and England, M.: On the water masses and mean circulation of the South Atlantic Ocean, J. Geophys. Res., 104, 20863–20883, https://doi.org/10.1029/1999JC900139, 1999.
Stramma, L., Fischer, J., and Reppin, J.: The North Brazil Undercurrent, Deep-Sea Res. Pt. I, 42, 773–795, https://doi.org/10.1016/0967-0637(95)00014-W, 1995.
Talley, L. D.: Shallow, intermediate and deep overturning components
of the global heat budget, J. Phys. Oceanogr., 33, 530–560,
https://doi.org/10.1175/1520-0485(2003)033<0530:SIADOC>2.0.CO;2,
2003.
Tchipalanga, P., Dengler, M., Brandt, P., Kopte, R., Macueria, M., Coelho, P., Ostrowski, M., and
Keenlyside, N. S.: Eastern Boundary Circulation and Hydrography Off Angola: Building Angolan
Oceanographic Capacities, Bull. Am. Meteorol. Soc., 99, 1589–1605, https://doi.org/10.1175/BAMS-D-17-0197.1, 2018.
Toole, J. M., Andres, M., Le Bras, I. A., Joyce, T. M., and McCartney, M.
S.: Moored observations of the deep western boundary current in the NW
Atlantic: 2004–2014, J. Geophys. Res.-Oceans 122, 7488–7505,
https://doi.org/10.1002/2017JC012984, 2017.
Veleda, D. R. A., Araujo, M., Silva, M., Montagne, R., and Araujo, R.: Seasonal and interannual variability of the southern south equatorial bifurcation and meridional transport along the eastern
Brazilian edge, Trop. Oceanogr., 39, 27–59, https://doi.org/10.5914/tropocean.v39i1.5176, 2011.
Watts, D. R. and Kontoyiannis, H.: Deep-ocean bottom pressure
measurement–Drift removal and performance, J. Atmos. Ocean. Tech., 7,
296–306, https://doi.org/10.1175/1520-0426(1990)007<0296:DOBPMD>2.0.CO;2, 1990.
Wienders, N., Arhan, M., and Mercier, H.: Circulation at the western boundary of the South and Equatorial Atlantic: exchanges with the ocean interior, J. Mar. Res., 58, 1007–1039, https://doi.org/10.1357/002224000763485782, 2000.
Worthington, E. L., Frajka-Williams, E., and McCarthy, G. D.: Estimating the
deep overturning transport variability at 26∘ N using bottom
pressure recorders, J. Geoph. Res.-Oceans, 124, 335–348,
https://doi.org/10.1029/2018JC014221, 2019.
Zantopp, R., Fischer, J., Visbeck, M., and Karstensen, J.: From interannual
to decadal: 17 years of boundary current transports at the exit of the
Labrador Sea. J. Geophys. Res.-Oceans, 122, 1724–1748.
https://doi.org/10.1002/2016JC012271, 2017.
Zhang, D., Msadek, R., McPhaden, M. J., and Delworth, T.: Multidecadal
variability of the North Brazil Current and its connection to the Atlantic
meridional overturning circulation, J. Geophys. Res., 116,
https://doi.org/10.1029/2010JC006812, 2011.
Zhao, J. and Johns, W. E.: Wind-forced interannual variability of the
Atlantic Meridional Overturning Circulation at 26.5∘ N, J.
Geophys. Res.-Oceans, 119, 2403–2419, https://doi.org/10.1002/2013JC009407, 2014.
Short summary
The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the climate system. Understanding its structure and variability is a key priority for many scientists. Here, we present the first estimate of AMOC variations for the tropical South Atlantic from the TRACOS array at 11° S. Over the observed period, the AMOC was dominated by seasonal variability. We investigate the respective mechanisms with an ocean model and find that different wind-forced waves play a big role.
The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the climate...
