Articles | Volume 20, issue 5
https://doi.org/10.5194/os-20-1281-2024
© Author(s) 2024. 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-20-1281-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The formation and ventilation of an oxygen minimum zone in a simple model for latitudinally alternating zonal jets
Eike E. Köhn
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zurich, Switzerland
Richard J. Greatbatch
CORRESPONDING AUTHOR
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Faculty of Mathematics and Natural Sciences, University of Kiel, Kiel, Germany
Peter Brandt
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Faculty of Mathematics and Natural Sciences, University of Kiel, Kiel, Germany
Martin Claus
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Related authors
No articles found.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Léo C. Aroucha, Joke F. Lübbecke, Peter Brandt, Franziska U. Schwarzkopf, and Arne Biastoch
Ocean Sci., 21, 661–678, https://doi.org/10.5194/os-21-661-2025, https://doi.org/10.5194/os-21-661-2025, 2025
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.
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).
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.
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.
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.
Jufen Lai, Richard J. Greatbatch, and Martin Claus
Ocean Sci., 19, 421–430, https://doi.org/10.5194/os-19-421-2023, https://doi.org/10.5194/os-19-421-2023, 2023
Short summary
Short summary
The El Niño Southern Oscillation (ENSO) has a global influence on weather and climate. Over most of the equatorial Pacific, where ENSO is focused, variations in sea surface height, such as measured by satellite, are strongly influenced by vertical displacements of the ocean thermocline. We show that linearly removing this influence leads to a time series of sea surface height that capture ENSO dynamics in the central Pacific, where ENSO variability has become more active in recent decades.
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.
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.
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
Short summary
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.
Cited articles
Anderson, D. L. and Killworth, P. D.: Non-linear propagation of long Rossby waves, Deep-Sea Res., 26, 1033–1049, 1979. a
Arakawa, A.: Design of the UCLA general circulation model, Tech. Rep. No 7, Dep. of Meteorology, UCLA, USA, https://ntrs.nasa.gov/citations/19730012781 (last access: 21 October 2024), 1972. a
Ascani, F., Firing, E., McCreary, J. P., Brandt, P., and Greatbatch, R. J.: The deep equatorial ocean circulation in wind-forced numerical solutions, J. Phys. Oceanogr., 45, 1709–1734, 2015. a
Brandt, P., Greatbatch, R. J., Claus, M., Didwischus, S.-H., Hormann, V., Funk, A., Hahn, J., Krahmann, G., Fischer, J., and Körtzinger, A.: Ventilation of the equatorial Atlantic by the equatorial deep jets, J. Geophys. Res.-Oceans, 117, https://doi.org/10.1029/2012JC008118, 2012. a
Brandt, P., Bange, H. W., Banyte, D., Dengler, M., Didwischus, S.-H., Fischer, T., Greatbatch, R. J., Hahn, J., Kanzow, T., Karstensen, J., Körtzinger, A., Krahmann, G., Schmidtko, S., Stramma, L., Tanhua, T., and Visbeck, M.: On the role of circulation and mixing in the ventilation of oxygen minimum zones with a focus on the eastern tropical North Atlantic, Biogeosciences, 12, 489–512, https://doi.org/10.5194/bg-12-489-2015, 2015. a, b, c, d, e, f, g, h, i
Breitburg, D., Levin, L. A., Oschlies, A., Grégoire, M., Chavez, F. P., Conley, D. J., Garçon, V., Gilbert, D., Gutiérrez, D., Isensee, K., Jacinto, G. S., Limburg, K. E., Montes, I., Naqvi, S. W. A., Pitcher, G. C., Rabalais, N. N., Roman, M. R., Rose, K. A., Seibel, B. A., Telszewski, M., Yasuhara, M., and Zhang, J.: Declining oxygen in the global ocean and coastal waters, Science, 359, eaam7240, https://doi.org/10.1126/science.aam7240, 2018. a
Calil, P. H.: High-Resolution, Basin-Scale Simulations Reveal the Impact of Intermediate Zonal Jets on the Atlantic Oxygen Minimum Zones, J. Adv. Model. Earth Sy., 15, e2022MS003158, https://doi.org/10.1029/2022MS003158, 2023. a, b, c
Chang, P., Zhang, R., Hazeleger, W., Wen, C., Wan, X., Ji, L., Haarsma, R. J., Breugem, W.-P., and Seidel, H.: Oceanic link between abrupt changes in the North Atlantic Ocean and the African monsoon, Nat. Geosci., 1, 444–448, 2008. a
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, 1998. a
Claus, M. and Köhn, E.: Model output and code for the publication “The formation and ventilation of an oxygen minimum zone in a simple model for latitudinally alternating zonal jets”, GEOMAR Helmholtz Centre for Ocean Research Kiel [data set], https://hdl.handle.net/20.500.12085/dd331654-413c-4157-8796-6edf4c4be207 (last access: 22 January 2024), 2024.
CMEMS: Global Ocean Physics Reanalysis (GLORYS12v1), Copernicus Marine Service [data set], https://doi.org/10.48670/moi-00021, 2023. a
De Szoeke, R. A. and Bennett, A. F.: Microstructure fluxes across density surfaces, J. Phys. Oceanogr., 23, https://doi.org/10.1175/1520-0485(1993)023<2254:MFADS>2.0.CO;2, 1993. a
Delpech, A., Cravatte, S., Marin, F., Ménesguen, C., and Morel, Y.: Deep eddy kinetic energy in the tropical Pacific from Lagrangian floats, J. Geophys. Res.-Oceans, 125, e2020JC016313, https://doi.org/10.1029/2020JC016313, 2020. a
Fratantoni, D. M. and Richardson, P. L.: The evolution and demise of North Brazil Current rings, J. Phys. Oceanogr., 36, 1241–1264, 2006. a
Garcia, H. E., Weathers, K. W., Paver, C. R., Smolyar, I., Boyer, T. P., Locarnini, R. A., Zweng, M. M., Mishonov, A. V., Baranova, O. K., Seidov, D., and Reagan, J. R.: World Ocean Atlas 2018, Vol. 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Dissolved Oxygen Saturation, edited by: Mishonov, A., NOAA Atlas NESDIS 83, 38 pp., https://www.ncei.noaa.gov/archive/accession/NCEI-WOA18 (last access: 15 April 2020), 2019. a
Hahn, J., Brandt, P., Schmidtko, S., and Krahmann, G.: Decadal oxygen change in the eastern tropical North Atlantic, Ocean Sci., 13, 551–576, https://doi.org/10.5194/os-13-551-2017, 2017. a, b, c
James, I. and James, P.: Ultra-low-frequency variability in a simple atmospheric circulation model, Nature, 342, 53–55, 1989. a
Kirchner, K., Rhein, M., Hüttl-Kabus, S., and Böning, C. W.: On the spreading of South Atlantic Water into the northern hemisphere, J. Geophys. Res.-Oceans, 114, https://doi.org/10.1029/2008JC005165, 2009. a
Köhn, E. E.: Data Analysis scripts for OMZ ventilation by LAZJs publication, Zenodo [code], https://doi.org/10.5281/zenodo.11447769, 2024.
Leetmaa, A. and Bunker, A. F.: Updated charts of the mean annual wind stress, convergences in the Ekman layers, and Sverdrup transports in the North Atlantic, J. Mar. Res., 36, 311–322, 1978. a
Maximenko, N. A., Bang, B., and Sasaki, H.: Observational evidence of alternating zonal jets in the world ocean, Geophys. Res. Lett., 32, https://doi.org/10.1029/2005GL022728, 2005. a
Maximenko, N. A., Melnichenko, O. V., Niiler, P. P., and Sasaki, H.: Stationary mesoscale jet-like features in the ocean, Geophys. Res. Lett., 35, https://doi.org/10.1029/2008GL033267, 2008. a
Ménesguen, C., Delpech, A., Marin, F., Cravatte, S., Schopp, R., and Morel, Y.: Observations and mechanisms for the formation of deep equatorial and tropical circulation, Earth and Space Science, 6, 370–386, 2019. a
Peña-Izquierdo, J., van Sebille, E., Pelegrí, J. L., Sprintall, J., Mason, E., Llanillo, P. J., and Machín, F.: Water mass pathways to the North Atlantic oxygen minimum zone, J. Geophys. Res.-Oceans, 120, 3350–3372, 2015. a
Risien, C. M. and Chelton, D. B.: A global climatology of surface wind and wind stress fields from eight years of QuikSCAT scatterometer data, J. Phys. Oceanogr., 38, 2379–2413, 2008. a
Shchepetkin, A. F. and O'Brien, J. J.: A physically consistent formulation of lateral friction in shallow-water equation ocean models, Mon. Weather Rev., 124, 1285–1300, 1996. a
Stokes, G. G.: On the theory of oscillatory waves, Trans. Cam. Philos. Soc., 8, 441–455, 1847. a
Van Geen, A., Smethie Jr., W., Horneman, A., and Lee, H.: Sensitivity of the North Pacific oxygen minimum zone to changes in ocean circulation: A simple model calibrated by chlorofluorocarbons, J. Geophys. Res.-Oceans, 111, https://doi.org/10.1029/2005JC003192, 2006. a
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.
The latitudinally alternating zonal jets are a ubiquitous feature of the ocean. We use a simple...