Articles | Volume 21, issue 2
https://doi.org/10.5194/os-21-661-2025
© Author(s) 2025. 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-21-661-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
18 Mar 2025
Research article |
| 18 Mar 2025
| 18 Mar 2025
River discharge impacts coastal southeastern tropical Atlantic sea surface temperature and circulation: a model-based analysis
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Joke F. Lübbecke
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Peter Brandt
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Faculty of Mathematics and Natural Sciences, Kiel University, Kiel, Germany
Franziska U. Schwarzkopf
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Arne Biastoch
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Faculty of Mathematics and Natural Sciences, Kiel University, Kiel, Germany
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Yawouvi Dodji Soviadan, Miriam Beck, Joelle Habib, Alberto Baudena, Laetitia Drago, Alexandre Accardo, Remi Laxenaire, Sabrina Speich, Peter Brandt, Rainer Kiko, and Stemmann Lars
Biogeosciences, 22, 3485–3501, https://doi.org/10.5194/bg-22-3485-2025, https://doi.org/10.5194/bg-22-3485-2025, 2025
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Key parameters representing the gravity flux in global models are sinking speed and vertical attenuation of exported material. We calculate, for the first time, these parameters in situ in the ocean for six intermittent blooms followed by export events using high-resolution (3 d) time series of 0–1000 m depth profiles from imaging sensors mounted on an Argo float. We show that sinking speed depends not only on size but also on the morphology of the particles, with density being an important property.
Yannick Wölker, Willi Rath, Matthias Renz, and Arne Biastoch
EGUsphere, https://doi.org/10.5194/egusphere-2025-2782, https://doi.org/10.5194/egusphere-2025-2782, 2025
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The Atlantic Meridional Overturning Circulation (AMOC) is a large current system that helps regulate Earth's climate. Monitoring the AMOC relies on fixed instruments anchored to the seafloor. This study explores in a high-resolution model whether data from Argo floats, autonomous drifters collecting hydrographic profiles, can be used to monitor the AMOC cost-effectively with the help of Machine Learning. Results suggest that Argo floats can extend AMOC monitoring beyond current fixed arrays.
Florian Schütte, Johannes Hahn, Ivy Frenger, Arne Bendinger, Fehmi Dilmahamod, Marco Schulz, and Peter Brandt
EGUsphere, https://doi.org/10.5194/egusphere-2025-2175, https://doi.org/10.5194/egusphere-2025-2175, 2025
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We found extreme drops in oxygen levels in the tropical Atlantic linked to surprisingly long-lived, small subsurface eddies. These eddies are hidden beneath the surface (undetectable by satellites) and are unusually stable, even in the highly dynamic ocean near the equator. Using long-term measurements and computer models, we show that these features can strongly influence oxygen supply and potentially impact marine ecosystems.
Tobias Schulzki, Franziska U. Schwarzkopf, and Arne Biastoch
EGUsphere, https://doi.org/10.5194/egusphere-2025-571, https://doi.org/10.5194/egusphere-2025-571, 2025
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Exceptionally high ocean temperatures can cause long-lasting damage to marine ecosystems. Most existing knowledge about such temperature extremes is focused on near-surface waters, yet ecosystems also thrive at greater depths. In this study, we present a comprehensive analysis of temperature extremes across the entire Atlantic Ocean, from the surface to the seafloor. Our findings underscore the importance of the ocean circulation in driving extreme temperature events.
Hendrik Großelindemann, Frederic S. Castruccio, Gokhan Danabasoglu, and Arne Biastoch
Ocean Sci., 21, 93–112, https://doi.org/10.5194/os-21-93-2025, https://doi.org/10.5194/os-21-93-2025, 2025
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This study investigates the Agulhas Leakage and examines its role in the global ocean circulation. It utilises a high-resolution Earth system model and a preindustrial climate to look at the response of the Agulhas Leakage to the wind field and the Atlantic Meridional Overturning Circulation (AMOC) and its evolution under climate change. The Agulhas Leakage could influence the stability of the AMOC, whose possible collapse would impact the climate in the Northern Hemisphere.
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
This preprint is open for discussion and under review for Biogeosciences (BG).
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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.
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
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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.
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
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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.
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
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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.
Jake W. Casselman, Joke F. Lübbecke, Tobias Bayr, Wenjuan Huo, Sebastian Wahl, and Daniela I. V. Domeisen
Weather Clim. Dynam., 4, 471–487, https://doi.org/10.5194/wcd-4-471-2023, https://doi.org/10.5194/wcd-4-471-2023, 2023
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El Niño–Southern Oscillation (ENSO) has remote effects on the tropical North Atlantic (TNA), but the connections' nonlinearity (strength of response to an increasing ENSO signal) is not always well represented in models. Using the Community Earth System Model version 1 – Whole Atmosphere Community Climate Mode (CESM-WACCM) and the Flexible Ocean and Climate Infrastructure version 1, we find that the TNA responds linearly to extreme El Niño but nonlinearly to extreme La Niña for CESM-WACCM.
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
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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.
Torge Martin and Arne Biastoch
Ocean Sci., 19, 141–167, https://doi.org/10.5194/os-19-141-2023, https://doi.org/10.5194/os-19-141-2023, 2023
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How is the ocean affected by continued Greenland Ice Sheet mass loss? We show in a systematic set of model experiments that atmospheric feedback needs to be accounted for as the large-scale ocean circulation is more than twice as sensitive to the meltwater otherwise. Coastal winds, boundary currents, and ocean eddies play a key role in redistributing the meltwater. Eddy paramterization helps the coarse simulation to perform better in the Labrador Sea but not in the North Atlantic Current region.
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
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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.
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.
Takaya Uchida, Julien Le Sommer, Charles Stern, Ryan P. Abernathey, Chris Holdgraf, Aurélie Albert, Laurent Brodeau, Eric P. Chassignet, Xiaobiao Xu, Jonathan Gula, Guillaume Roullet, Nikolay Koldunov, Sergey Danilov, Qiang Wang, Dimitris Menemenlis, Clément Bricaud, Brian K. Arbic, Jay F. Shriver, Fangli Qiao, Bin Xiao, Arne Biastoch, René Schubert, Baylor Fox-Kemper, William K. Dewar, and Alan Wallcraft
Geosci. Model Dev., 15, 5829–5856, https://doi.org/10.5194/gmd-15-5829-2022, https://doi.org/10.5194/gmd-15-5829-2022, 2022
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Ocean and climate scientists have used numerical simulations as a tool to examine the ocean and climate system since the 1970s. Since then, owing to the continuous increase in computational power and advances in numerical methods, we have been able to simulate increasing complex phenomena. However, the fidelity of the simulations in representing the phenomena remains a core issue in the ocean science community. Here we propose a cloud-based framework to inter-compare and assess such simulations.
Jens Zinke, Takaaki K. Watanabe, Siren Rühs, Miriam Pfeiffer, Stefan Grab, Dieter Garbe-Schönberg, and Arne Biastoch
Clim. Past, 18, 1453–1474, https://doi.org/10.5194/cp-18-1453-2022, https://doi.org/10.5194/cp-18-1453-2022, 2022
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Salinity is an important and integrative measure of changes to the water cycle steered by changes to the balance between rainfall and evaporation and by vertical and horizontal movements of water parcels by ocean currents. However, salinity measurements in our oceans are extremely sparse. To fill this gap, we have developed a 334-year coral record of seawater oxygen isotopes that reflects salinity changes in the globally important Agulhas Current system and reveals its main oceanic drivers.
Ioana Ivanciu, Katja Matthes, Arne Biastoch, Sebastian Wahl, and Jan Harlaß
Weather Clim. Dynam., 3, 139–171, https://doi.org/10.5194/wcd-3-139-2022, https://doi.org/10.5194/wcd-3-139-2022, 2022
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Greenhouse gas concentrations continue to increase, while the Antarctic ozone hole is expected to recover during the twenty-first century. We separate the effects of ozone recovery and of greenhouse gases on the Southern Hemisphere atmospheric and oceanic circulation, and we find that ozone recovery is generally reducing the impact of greenhouse gases, with the exception of certain regions of the stratosphere during spring, where the two effects reinforce each other.
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.
Christina Schmidt, Franziska U. Schwarzkopf, Siren Rühs, and Arne Biastoch
Ocean Sci., 17, 1067–1080, https://doi.org/10.5194/os-17-1067-2021, https://doi.org/10.5194/os-17-1067-2021, 2021
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We estimate Agulhas leakage, water flowing from the Indian Ocean to the South Atlantic, in an ocean model with two different tools. The mean transport, variability and trend of Agulhas leakage is simulated comparably with both tools, emphasising the robustness of our method. If the experiments are designed differently, the mean transport of Agulhas leakage is altered, but not the trend. Agulhas leakage waters cool and become less salty south of Africa resulting in a density increase.
Ioana Ivanciu, Katja Matthes, Sebastian Wahl, Jan Harlaß, and Arne Biastoch
Atmos. Chem. Phys., 21, 5777–5806, https://doi.org/10.5194/acp-21-5777-2021, https://doi.org/10.5194/acp-21-5777-2021, 2021
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The Antarctic ozone hole has driven substantial dynamical changes in the Southern Hemisphere atmosphere over the past decades. This study separates the historical impacts of ozone depletion from those of rising levels of greenhouse gases and investigates how these impacts are captured in two types of climate models: one using interactive atmospheric chemistry and one prescribing the CMIP6 ozone field. The effects of ozone depletion are more pronounced in the model with interactive chemistry.
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
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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.
Josefine Herrford, Peter Brandt, Torsten Kanzow, Rebecca Hummels, Moacyr Araujo, and Jonathan V. Durgadoo
Ocean Sci., 17, 265–284, https://doi.org/10.5194/os-17-265-2021, https://doi.org/10.5194/os-17-265-2021, 2021
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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.
Cited articles
Alory, G., Da-Allada, C. Y., Djakouré, S., Dadou, I., Jouanno, J., and Loemba, D. P.: Coastal Upwelling Limitation by Onshore Geostrophic Flow in the Gulf of Guinea Around the Niger River Plume, Front. Mar. Sci., 7, 607216, https://doi.org/10.3389/fmars.2020.607216, 2021.
Aloysius, N. and Saiers, J.: Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin, Hydrol. Earth Syst. Sci., 21, 4115–4130, https://doi.org/10.5194/hess-21-4115-2017, 2017.
Alsdorf, D., Beighley, E., Laraque, A., Lee, H., Tshimanga, R., O'Loughlin, F., Mahé, G., Dinga, B., Moukandi, G., and Spencer, R. G. M.: Opportunities for hydrologic research in the Congo Basin, Rev. Geophys., 54, 378–409, https://doi.org/10.1002/2016RG000517, 2016.
Aroucha, L. C. and Schwarzkopf, F. U.: Supplementary Data to: River discharge impacts coastal Southeastern Tropical Atlantic sea surface temperature and circulation: a model-based analysis, GEOMAR Helmholtz Centre for Ocean Research Kiel [data set], https://hdl.handle.net/20.500.12085/2b927bcd-afab-4bc6-ba97-634d09435daa (last access: 10 January 2025), 2024.
Aroucha, L. C., Lübbecke, J. F., Körner, M., Imbol Koungue, R. A., and Awo, F. M.: The Influence of Freshwater Input on the Evolution of the 1995 Benguela Niño, J. Geophys. Res.-Oceans, 129, e2023JC020241, https://doi.org/10.1029/2023JC020241, 2024.
Awo, F. M., Rouault, M., Ostrowski, M., Tomety, F. S., Da-Allada, C. Y., and Jouanno, J.: Seasonal Cycle of Sea Surface Salinity in the Angola Upwelling System, J. Geophys. Res.-Oceans, 127, e2022JC018518, https://doi.org/10.1029/2022JC018518, 2022.
Ayissi, F. F. B. K., Da-Allada, C. Y., Baloïtcha, E., Worou, L. O., and Tilmes, S.: Changes in coastal upwelling in the northern Gulf of Guinea under Stratospheric Aerosol Injection, Reg. Stud. Mar. Sci., 76, 103607, https://doi.org/10.1016/j.rsma.2024.103607, 2024.
Biastoch, A., Schwarzkopf, F. U., Getzlaff, K., Rühs, S., Martin, T., Scheinert, M., Schulzki, T., Handmann, P., Hummels, R., and Böning, C. W.: Regional imprints of changes in the Atlantic Meridional Overturning Circulation in the eddy-rich ocean model VIKING20X, Ocean Sci., 17, 1177–1211, https://doi.org/10.5194/os-17-1177-2021, 2021.
Bonino, G., Masina, S., Iovino, D., Storto, A., and Tsujino, H.: Eastern Boundary Upwelling Systems response to different atmospheric forcing in a global eddy-permitting ocean model, J. Marine Syst., 197, 103178, https://doi.org/10.1016/j.jmarsys.2019.05.004, 2019.
Bordbar, M. H., Mohrholz, V., and Schmidt, M.: The relation of wind-driven coastal and offshore upwelling in the Benguela Upwelling System, J. Phys. Oceanogr., 51, 3117–3133, https://doi.org/10.1175/JPO-D-20-0297.1, 2021.
Boutin, J., Reul, N., Koehler, J., Martin, A., Catany, R., Guimbard, S., Rouffi, F., Vergely, J. L., Arias, M., Chakroun, M., Corato, G., Estella-Perez, V., Hasson, A., Josey, S., Khvorostyanov, D., Kolodziejczyk, N., Mignot, J., Olivier, L., Reverdin, G., Stammer, D., Supply, A., Thouvenin-Masson, C., Turiel, A., Vialard, J., Cipollini, P., Donlon, C., Sabia, R., and Mecklenburg, S.: Satellite-Based Sea Surface Salinity Designed for Ocean and Climate Studies, J. Geophys. Res.-Oceans, 126, e2021JC017676, https://doi.org/10.1029/2021JC017676, 2021.
Brandt, P., Bordbar, M. H., Coelho, P., Koungue, R. A. I., Körner, M., Lamont, T., Lübbecke, J. F., Mohrholz, V., Prigent, A., Roch, M., Schmidt, M., Van Der Plas, A. K., and Veitch, J.: Physical Drivers of Southwest African Coastal Upwelling and Its Response to Climate Variability and Change, in: Sustainability of Southern African Ecosystems under Global Change, vol. 248, edited by: Von Maltitz, G. P., Midgley, G. F., Veitch, J., Brümmer, C., Rötter, R. P., Viehberg, F. A., and Veste, M., Springer International Publishing, Cham, 221–257, https://doi.org/10.1007/978-3-031-10948-5_9, 2024.
Brandt, P. and Krahmann, G.: Physical oceanography (ADCP) from mooring KPO_1107, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.909911, 2019.
Brandt, P., Imbol Koungue, R. A., Krahmann, G., and Dengler, M.: Physical oceanography from mooring KPO_1235, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.962193, 2023.
Campbell, D.: The Congo River basin, in: The World's Largest Wetlands: Ecology and Conservation, edited by: Fraser, L. H. and Keddy, P. A., Cambridge University Press, Cambridge, 149–165, https://doi.org/10.1017/CBO9780511542091.006, 2005.
Chandanpurkar, H. A., Lee, T., Wang, X., Zhang, H., Fournier, S., Fenty, I., Fukumori, I., Menemenlis, D., Piecuch, C. G., Reager, J. T., Wang, O., and Worden, J.: Influence of Nonseasonal River Discharge on Sea Surface Salinity and Height, J. Adv. Model. Earth Sy., 14, e2021MS002715, https://doi.org/10.1029/2021MS002715, 2022.
Chao, Y., Farrara, J. D., Schumann, G., Andreadis, K. M., and Moller, D.: Sea surface salinity variability in response to the Congo river discharge, Cont. Shelf Res., 99, 35–45, https://doi.org/10.1016/j.csr.2015.03.005, 2015.
Chelton, D. B., deSzoeke, R. A., Schlax, M. G., El Naggar, K., and Siwertz, N.: Geographical Variability of the First Baroclinic Rossby Radius of Deformation, J. Phys. Oceanogr., 28, 433–460, https://doi.org/10.1175/1520-0485(1998)028<0433:GVOTFB>2.0.CO;2, 1998.
Dai, A. and Trenberth, K. E.: Estimates of Freshwater Discharge from Continents: Latitudinal and Seasonal Variations, J. Hydrometeorol., 3, 660–687, https://doi.org/10.1175/1525-7541(2002)003<0660:EOFDFC>2.0.CO;2, 2002.
De La Vara, A., Cabos, W., Sein, D. V., Sidorenko, D., Koldunov, N. V., Koseki, S., Soares, P. M. M., and Danilov, S.: On the impact of atmospheric vs oceanic resolutions on the representation of the sea surface temperature in the South Eastern Tropical Atlantic, Clim. Dynam., 54, 4733–4757, https://doi.org/10.1007/s00382-020-05256-9, 2020.
Denamiel, C., Budgell, W. P., and Toumi, R.: The Congo River plume: Impact of the forcing on the far-field and near-field dynamics, J. Geophys. Res.-Oceans, 118, 964–989, https://doi.org/10.1002/jgrc.20062, 2013.
Dengler, M. and Krahmann, G.: Physical oceanography (ADCP) from mooring KPO_1153, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.909913, 2019.
FAO: Fishery and Aquaculture Country Profiles, Angola, 2020, Country Profile Fact Sheets, Fisheries and Aquaculture Division, Rome, https://www.fao.org/fishery/en/facp/ago?lang= en (last access: 22 July 2024), updated 7 February 2022.
Farneti, R., Stiz, A., and Ssebandeke, J. B.: Improvements and persistent biases in the southeast tropical Atlantic in CMIP models, npj Clim. Atmos. Sci., 5, 42, https://doi.org/10.1038/s41612-022-00264-4, 2022.
Fennel, W.: Theory of the Benguela Upwelling System, J. Phys. Oceanogr., 29, 177–190, https://doi.org/10.1175/1520-0485(1999)029<0177:TOTBUS>2.0.CO;2, 1999.
Florenchie, P., Reason, C. J. C., Lutjeharms, J. R. E., Rouault, M., Roy, C., and Masson, S.: Evolution of Interannual Warm and Cold Events in the Southeast Atlantic Ocean, J. Climate, 17, 2318–2334, https://doi.org/10.1175/1520-0442(2004)017<2318:EOIWAC>2.0.CO;2, 2004.
Fong, D. A. and Geyer, W. R.: The Alongshore Transport of Freshwater in a Surface-Trapped River Plume, J. Phys. Oceanogr., 32, 957–972, https://doi.org/10.1175/1520-0485(2002)032<0957:TATOFI>2.0.CO;2, 2002.
Gammelsrød, T., Bartholomae, C. H., Boyer, D. C., Filipe, V. L. L., and O'Toole, M. J.: Intrusion of warm surface water along the Angolan-Namibian coast in February–March 1995: the 1995 Benguela Nino, S. Afr. J. Marine Sci., 19, 41–56, https://doi.org/10.2989/025776198784126719, 1998.
Gévaudan, M., Jouanno, J., Durand, F., Morvan, G., Renault, L., and Samson, G.: Influence of ocean salinity stratification on the tropical Atlantic Ocean surface, Clim. Dynam., 57, 321–340, https://doi.org/10.1007/s00382-021-05713-z, 2021.
Hopkins, J., Lucas, M., Dufau, C., Sutton, M., Stum, J., Lauret, O., and Channelliere, C.: Detection and variability of the Congo River plume from satellite derived sea surface temperature, salinity, ocean colour and sea level, Remote Sens. Environ., 139, 365–385, https://doi.org/10.1016/j.rse.2013.08.015, 2013.
Houndegnonto, O. J., Kolodziejczyk, N., Maes, C., Bourlès, B., Da-Allada, C. Y., and Reul, N.: Seasonal Variability of Freshwater Plumes in the Eastern Gulf of Guinea as Inferred From Satellite Measurements, J. Geophys. Res.-Oceans, 126, e2020JC017041, https://doi.org/10.1029/2020JC017041, 2021.
Hua, W., Zhou, L., Nicholson, S. E., Chen, H., and Qin, M.: Assessing reanalysis data for understanding rainfall climatology and variability over Central Equatorial Africa, Clim. Dynam., 53, 651–669, https://doi.org/10.1007/s00382-018-04604-0, 2019.
Huang, B., Liu, C., Banzon, V., Freeman, E., Graham, G., Hankins, B., Smith, T., and Zhang, H.-M.: Improvements of the Daily Optimum Interpolation Sea Surface Temperature (DOISST) Version 2.1, J. Climate, 34, 2923–2939, https://doi.org/10.1175/JCLI-D-20-0166.1, 2021.
Hummels, R., Imbol Koungue, R. A., Brandt, P., and Krahmann, G.: Physical oceanography from mooring KPO_1215, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.939249, 2021.
Jarre, A., Hutchings, L., Kirkman, S. P., Kreiner, A., Tchipalanga, P. C. M., Kainge, P., Uanivi, U., Van Der Plas, A. K., Blamey, L. K., Coetzee, J. C., Lamont, T., Samaai, T., Verheye, H. M., Yemane, D. G., Axelsen, B. E., Ostrowski, M., Stenevik, E. K., and Loeng, H.: Synthesis: climate effects on biodiversity, abundance and distribution of marine organisms in the Benguela, Fisheries Ocean., 24, 122–149, https://doi.org/10.1111/fog.12086, 2015.
Jarugula, S. and McPhaden, M. J.: Indian Ocean Dipole affects eastern tropical Atlantic salinity through Congo River Basin hydrology, Commun. Earth Environ., 4, 366, https://doi.org/10.1038/s43247-023-01027-6, 2023.
Jing, Z., Wang, S., Wu, L., Wang, H., Zhou, S., Sun, B., Chen, Z., Ma, X., Gan, B., and Yang, H.: Geostrophic flows control future changes of oceanic eastern boundary upwelling, Nat. Clim. Change, 13, 148–154, https://doi.org/10.1038/s41558-022-01588-y, 2023.
Kirkman, S., Blamey, L., Lamont, T., Field, J., Bianchi, G., Huggett, J., Hutchings, L., Jackson-Veitch, J., Jarre, A., Lett, C., Lipiński, M., Mafwila, S., Pfaff, M., Samaai, T., Shannon, L., Shin, Y.-J., Van Der Lingen, C., and Yemane, D.: Spatial characterisation of the Benguela ecosystem for ecosystem-based management, Afr. J. Mar. Sci., 38, 7–22, https://doi.org/10.2989/1814232X.2015.1125390, 2016.
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: THE ANGOLA CURRENT AS OBSERVED AT 11° S, J. Geophys. Res.-Oceans, 122, 1177–1189, https://doi.org/10.1002/2016JC012374, 2017.
Körner, M., Brandt, P., and Dengler, M.: Seasonal cycle of sea surface temperature in the tropical Angolan Upwelling System, Ocean Sci., 19, 121–139, https://doi.org/10.5194/os-19-121-2023, 2023.
Körner, M., Brandt, P., Illig, S., Dengler, M., Subramaniam, A., Bachèlery, M.-L., and Krahmann, G.: Coastal trapped waves and tidal mixing control primary production in the tropical Angolan upwelling system, Sci. Adv., 10, eadj6686, https://doi.org/10.1126/sciadv.adj6686, 2024.
Koseki, S., Keenlyside, N., Demissie, T., Toniazzo, T., Counillon, F., Bethke, I., Ilicak, M., and Shen, M.-L.: Causes of the large warm bias in the Angola–Benguela Frontal Zone in the Norwegian Earth System Model, Clim. Dynam., 50, 4651–4670, https://doi.org/10.1007/s00382-017-3896-2, 2018.
Koseki, S., Giordani, H., and Goubanova, K.: Frontogenesis of the Angola–Benguela Frontal Zone, Ocean Sci., 15, 83–96, https://doi.org/10.5194/os-15-83-2019, 2019.
Krahmann, G.: Physical oceanography from mooring KPO_1106 and KPO_1107, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.870917, 2017.
Kurian, J., Li, P., Chang, P., Patricola, C. M., and Small, J.: Impact of the Benguela coastal low-level jet on the southeast tropical Atlantic SST bias in a regional ocean model, Clim. Dynam., 56, 2773–2800, https://doi.org/10.1007/s00382-020-05616-5, 2021.
Lellouche, J.-M., Greiner, E., Bourdallé Badie, R., Garric, G., Melet, A., Drévillon, M., Bricaud, C., Hamon, M., Le Galloudec, O., Regnier, C., Candela, T., Testut, C-E., Gasparin, F., Ruggiero, G., Benkiran, M., Drillet, Y. and Le Traon, P-Y.: The copernicus global 1/12 oceanic and sea ice GLORYS12 reanalysis, Front. Earth Sci., 9, 1–27, https://doi.org/10.3389/feart.2021.698876, 2021.
Levitus, S., Boyer, T. P., Conkright, M. E., Brien, T. O., Antonov, J., Stephens, C., Stathoplos, L., Johnson, D., and Gelfeld, R.: NOAA Atlas NESDIS 18, World Ocean Database 1998: Volume 1: Introduction, U.S. Gov. Printing Office, Wash., D.C., gov.noaa.nodc:0095184, 0095184 1998.
Lübbecke, J. F., Böning, C. W., Keenlyside, N. S., and Xie, S.: On the connection between Benguela and equatorial Atlantic Niños and the role of the South Atlantic Anticyclone, J. Geophys. Res., 115, 2009JC005964, https://doi.org/10.1029/2009JC005964, 2010.
Lübbecke, J. F., Brandt, P., Dengler, M., Kopte, R., Lüdke, J., Richter, I., Sena Martins, M., and Tchipalanga, P. C. M.: Causes and evolution of the southeastern tropical Atlantic warm event in early 2016, Clim, Dynam., 53, 261–274, https://doi.org/10.1007/s00382-018-4582-8, 2019.
Madec, G. and the NEMO team: NEMO ocean engine – version 3.6, Note du Pôle de modélisation, Institut Pierre-Simon Laplace (IPSL), France, 406 pp., ISSN 1288-1619, 2016.
Marchesiello, P. and Estrade, P.: Upwelling limitation by onshore geostrophic flow, J. Mar. Res., 68, 37–62, https://doi.org/10.1357/002224010793079004, 2010.
Martins, M. S. and Stammer, D.: Interannual Variability of the Congo River Plume-Induced Sea Surface Salinity, Remote Sens., 14, 1013, https://doi.org/10.3390/rs14041013, 2022.
Materia, S., Gualdi, S., Navarra, A., and Terray, L.: The effect of Congo River freshwater discharge on Eastern Equatorial Atlantic climate variability, Clim. Dynam., 39, 2109–2125, https://doi.org/10.1007/s00382-012-1514-x, 2012.
McPhaden, M. J., Jarugula, S., Aroucha, L. C., and Lübbecke, J.: Indian Ocean Dipole intensifies Benguela Niño through Congo River discharge. Commun Earth Environ 5, 779, https://doi.org/10.1038/s43247-024-01955-x, 2024.
Meade, R. H. and Emery, K. O.: Sea Level as Affected by River Runoff, Eastern United States, Science, 173, 425–428, https://doi.org/10.1126/science.173.3995.425, 1971.
Müller, O. V., McGuire, P. C., Vidale, P. L., and Hawkins, E.: River flow in the near future: a global perspective in the context of a high-emission climate change scenario, Hydrol. Earth Syst. Sci., 28, 2179–2201, https://doi.org/10.5194/hess-28-2179-2024, 2024.
Munzimi, Y. A., Hansen, M. C., and Asante, K. O.: Estimating daily streamflow in the Congo Basin using satellite-derived data and a semi-distributed hydrological model, Hydrolog. Sci. J., 64, 1472–1487, https://doi.org/10.1080/02626667.2019.1647342, 2019.
Ngakala, R. D., Alory, G., Da-Allada, C. Y., Kom, O. E., Jouanno, J., Rath, W., and Baloïtcha, E.: Joint observation–model mixed-layer heat and salt budgets in the eastern tropical Atlantic, Ocean Sci., 19, 535–558, https://doi.org/10.5194/os-19-535-2023, 2023.
Nyadjro, E. S., Foli, B. A. K., Agyekum, K. A., Wiafe, G., and Tsei, S.: Seasonal Variability of Sea Surface Salinity in the NW Gulf of Guinea from SMAP Satellite, Remote Sens. Earth Syst. Sci., 5, 83–94, https://doi.org/10.1007/s41976-021-00061-2, 2022.
Piecuch, C. G., Bittermann, K., Kemp, A. C., Ponte, R. M., Little, C. M., Engelhart, S. E., and Lentz, S. J.: River-discharge effects on United States Atlantic and Gulf coast sea-level changes, P. Natl. Acad. Sci. USA, 115, 7729–7734, https://doi.org/10.1073/pnas.1805428115, 2018.
Prigent, A. and Farneti, R.: An assessment of equatorial Atlantic interannual variability in Ocean Model Intercomparison Project (OMIP) simulations, Ocean Sci., 20, 1067–1086, https://doi.org/10.5194/os-20-1067-2024, 2024.
Reynolds, R. W., Smith, T. M., Liu, C., Chelton, D. B., Casey, K. S., and Schlax, M. G.: Daily High-Resolution-Blended Analyses for Sea Surface Temperature, J. Climate, 20, 5473–5496, https://doi.org/10.1175/2007JCLI1824.1, 2007.
Richter, I.: Climate model biases in the eastern tropical oceans: causes, impacts and ways forward, WIREs Clim. Change, 6, 345–358, https://doi.org/10.1002/wcc.338, 2015.
Rio, M.-H., Mulet, S., and Picot, N.: Beyond GOCE for the ocean circulation estimate: Synergetic use of altimetry, gravimetry, and in situ data provides new insight into geostrophic and Ekman currents, Geophys. Res. Lett., 41, 8918–8925, https://doi.org/10.1002/2014GL061773, 2014.
Roch, M., Brandt, P., Schmidtko, S., Vaz Velho, F., and Ostrowski, M.: Southeastern Tropical Atlantic Changing From Subtropical to Tropical Conditions, Front. Mar. Sci., 8, 748383, https://doi.org/10.3389/fmars.2021.748383, 2021.
Rouault, M., Illig, S., Bartholomae, C., Reason, C. J. C., and Bentamy, A.: Propagation and origin of warm anomalies in the Angola Benguela upwelling system in 2001, J. Marine Syst., 68, 473–488, https://doi.org/10.1016/j.jmarsys.2006.11.010, 2007.
Rouault, M., Illig, S., Lübbecke, J., and Koungue, R. A. I.: Origin, development and demise of the 2010–2011 Benguela Niño, J. Marine Syst., 188, 39–48, https://doi.org/10.1016/j.jmarsys.2017.07.007, 2018.
Rühs, S., Schmidt, C., Schubert, R., Schulzki, T., Schwarzkop, F., U., Le Bars, D., and Biastoch, A.: Robust estimates for the decadal evolution of Agulhas leakage from the 1960s to the 2010s, Commun. Earth Environ., 3, 318, https://doi.org/10.1038/s43247-022-00643-y, 2022.
Saha, A., Serra, N., and Stammer, D.: Growth and Decay of Northwestern Tropical Atlantic Barrier Layers, J. Geophys. Res.-Oceans, 126, e2020JC016956, https://doi.org/10.1029/2020JC016956, 2021.
Schmidt, C., Schwarzkopf, F. U., Rühs, S., and Biastoch, A.: Characteristics and robustness of Agulhas leakage estimates: an inter-comparison study of Lagrangian methods, Ocean Sci., 17, 1067–1080, https://doi.org/10.5194/os-17-1067-2021, 2021.
Schwarzkopf, F. U., Biastoch, A., Böning, C. W., Chanut, J., Durgadoo, J. V., Getzlaff, K., Harlaß, J., Rieck, J. K., Roth, C., Scheinert, M. M., and Schubert, R.: The INALT family – a set of high-resolution nests for the Agulhas Current system within global NEMO ocean/sea-ice configurations, Geosci. Model Dev., 12, 3329–3355, https://doi.org/10.5194/gmd-12-3329-2019, 2019.
Shannon, L. V., Boyd, A. J., Brundrit, G. B., and Taunton-Clark, J.: On the existence of an El Niño-type phenomenon in the Benguela System, J. Mar. Res., 44, 495–520, https://doi.org/10.1357/002224086788403105, 1986.
Small, R. J., Kurian, J., Chang, P., Xu, G., Tsujino, H., Yeager, S., Danabasoglu, G., Kim, W. M., Altuntas, A., and Castruccio, F.: Eastern Boundary Upwelling Systems in Ocean–Sea Ice Simulations Forced by CORE and JRA55-do: Mean State and Variability at the Surface, J. Climate, 37, 2821–2848, https://doi.org/10.1175/JCLI-D-23-0511.1, 2024.
SO-HYBAM: Amazon Basin water resources observation service, https://hybam.obs-mip.fr/, last access: 25 June 2024.
Sorí, R., Nieto, R., Vicente-Serrano, S. M., Drumond, A., and Gimeno, L.: A Lagrangian perspective of the hydrological cycle in the Congo River basin, Earth Syst. Dynam., 8, 653–675, https://doi.org/10.5194/esd-8-653-2017, 2017.
Sowman, M. and Cardoso, P.: Small-scale fisheries and food security strategies in countries in the Benguela Current Large Marine Ecosystem (BCLME) region: Angola, Namibia and South Africa, Mar. Policy, 34, 1163–1170, https://doi.org/10.1016/j.marpol.2010.03.016, 2010.
Tchipalanga, P., Dengler, M., Brandt, P., Kopte, R., Macuéria, M., Coelho, P., Ostrowski, M., Keenlyside, N. S. Eastern boundary circulation and hydrography off Angola: Building Angolan oceanographic capacities, B. Am. Meteorol. Soc., 99, 1589–1605, https://doi.org/10.1175/BAMS-D-17-0197.1, 2018.
Tomety, F. S., Illig, S., Ostrowski, M., Awo, F. M., Bachèlery, M.-L., Keenlyside, N., and Rouault, M.: Long-term climatological trends driving the recent warming along the Angolan and Namibian coasts, Clim. Dynam., 62, 7763–7782, https://doi.org/10.1007/s00382-024-07305-z, 2024.
Topé, G. D. A., Alory, G., Djakouré, S., Da-Allada, C. Y., Jouanno, J., and Morvan, G.: How does the Niger river warm coastal waters in the northern Gulf of Guinea?, Front. Mar. Sci., 10, 1187202, https://doi.org/10.3389/fmars.2023.1187202, 2023.
Tsujino, H., Urakawa, S., Nakano, H., Small, R. J., Kim, W. M., Yeager, S. G., Danabasoglu, G., Suzuki, T., Bamber, J. L., Bentsen, M., Böning, C. W., Bozec, A., Chassignet, E. P., Curchitser, E., Boeira Dias, F., Durack, P. J., Griffies, S. M., Harada, Y., Ilicak, M., Josey, S. A., Kobayashi, C., Kobayashi, S., Komuro, Y., Large, W. G., Le Sommer, J., Marsland, S. J., Masina, S., Scheinert, M., Tomita, H., Valdivieso, M., and Yamazaki, D.: JRA-55 based surface dataset for driving ocean–sea-ice models (JRA55-do), Ocean Modell., 130, 79–139, https://doi.org/10.1016/j.ocemod.2018.07.002, 2018.
White, R. H. and Toumi, R.: River flow and ocean temperatures: The Congo River, J. Geophys. Res.-Oceans, 119, 2501–2517, https://doi.org/10.1002/2014JC009836, 2014.
Zhang, R.-H. and Busalacchi, A. J.: Freshwater Flux (FWF)-Induced Oceanic Feedback in a Hybrid Coupled Model of the Tropical Pacific, J. Climate, 22, 853–879, https://doi.org/10.1175/2008JCLI2543.1, 2009.
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.
The west African coastal region sustains highly productive fisheries and marine ecosystems...
