Articles | Volume 21, issue 2
https://doi.org/10.5194/os-21-727-2025
© 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-21-727-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
An estimate of the eddy diffusivity tensor from observed and simulated Lagrangian trajectories in the Benguela Upwelling System
Institute of Environmental Physics, University of Bremen, Bremen, Germany
Birte Gülk
LOCEAN, Sorbonne Université–CNRS–IRD–MNHN, Paris, France
Julia Dräger-Dietel
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany
Alexa Griesel
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany
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At the southern boundary of the Antarctic Circumpolar Current, relatively warm waters encounter the colder waters surrounding Antarctica. Observations from underwater vehicles and altimetry show that medium-sized cold-core eddies influence the southern boundary's barrier properties by strengthening the slopes of constant density lines across it and amplifying its associated jet. As a result, the ability of exchanging properties, such as heat, across the southern boundary is reduced.
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Ria Oelerich, Karen J. Heywood, Gillian M. Damerell, Marcel du Plessis, Louise C. Biddle, and Sebastiaan Swart
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The Polar Front in the northwestern Barents Sea: structure, variability and mixing
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Eivind H. Kolås, Ilker Fer, and Till M. Baumann
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Felipe L. L. Amorim, Julien Le Meur, Achim Wirth, and Vanessa Cardin
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Ryan P. North, Julia Dräger-Dietel, and Alexa Griesel
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The Benguela upwelling region off the coast of Namibia supplies cold water from the deep ocean that is transported offshore in finger-like structures called filaments. We investigate one major filament using measurements from a ship that crossed it multiple times and with mutiple buoys that follow the ocean currents. We find that the motions associated with the filament enhance the kinetic energy at small scales and provide a pathway for mixing of water and turbulent dissipation of energy.
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At the southern boundary of the Antarctic Circumpolar Current, relatively warm waters encounter the colder waters surrounding Antarctica. Observations from underwater vehicles and altimetry show that medium-sized cold-core eddies influence the southern boundary's barrier properties by strengthening the slopes of constant density lines across it and amplifying its associated jet. As a result, the ability of exchanging properties, such as heat, across the southern boundary is reduced.
Arthur Coquereau and Nicholas P. Foukal
Ocean Sci., 19, 1393–1411, https://doi.org/10.5194/os-19-1393-2023, https://doi.org/10.5194/os-19-1393-2023, 2023
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Understanding meltwater circulation around Greenland is crucial as it could influence climate variability but difficult as data are scarce. Here, we use 34 surface drifters to evaluate satellite-derived surface currents and show that satellite data recover the general structure of the flow and can recreate the pathways of particles around the southern tip of Greenland. This result permits a wide range of work to proceed looking at long-term changes in the circulation of the region since 1993.
Cited articles
Bachman, S., Fox-Kemper, B., and Bryan, F. O.: A diagnosis of anisotropic eddy diffusion from a high-resolution global ocean model, J. Adv. Model. Earth Sy., 12, 1–14, https://doi.org/10.1029/2019MS001904, 2020. a
Ballarotta, M., Ubelmann, C., Pujol, M.-I., Taburet, G., Fournier, F., Legeais, J.-F., Faugère, Y., Delepoulle, A., Chelton, D., Dibarboure, G., and Picot, N.: On the resolutions of ocean altimetry maps, Ocean Sci., 15, 1091–1109, https://doi.org/10.5194/os-15-1091-2019, 2019. a
Berger, W. and Wefer, G.: On the reconstruction of upwelling history: Namibia upwelling in context, Mar. Geol., 180, 3–28, https://doi.org/10.1016/S0025-3227(01)00203-1, 2002. a
Bonjean, F. and Lagerloef, G.: Diagnostic model and analysis of the surface currents in the tropical Pacific Ocean, J. Phys. Oceanogr., 32, 2938–2954, https://doi.org/10.1175/1520-0485(2002)032<2938:DMAAOT>2.0.CO;2, 2002. a
Capet, X., McWilliams, F., Penven, J. C., and Marchesiello, P.: Eddies in eastern boundary subtropical upwelling systems, Geoph. Monog. Series, 177, 131–147, https://doi.org/10.1029/177GM10, 2008. a, b
Chen, R., McClean, J. L., Gille, S. T., and Griesel, A.: Isopycnal eddy diffusivities and critical layers in the Kuroshio extension from an eddying ocean model, J. Phys. Oceanogr., 44, 2191–2211, https://doi.org/10.1175/JPO-D-13-0258.1, 2014. a, b
Chen, R., Gille, S., McClean, J., Flierl, G., and Griesel, A.: A multi-wavenumber theory for eddy diffusivities and its application to the southeast Pacific (DIMES) region, J. Phys. Oceanogr., 45, 1877–1896, https://doi.org/10.1175/JPO-D-14-0229.1, 2015. a
Chouksey, A., Griesel, A., Chouksey, M., and Eden, C.: Changes in global ocean circulation due to isopycnal diffusion, J. Phys. Oceanogr., 52, 2219–2235, https://doi.org/10.1175/JPO-D-21-0205.1, 2022. a
Davis, R. E.: Observing the general circulation with floats, Deep-Sea Res., 38, 531–571, https://doi.org/10.1016/S0198-0149(12)80023-9, 1991. a, b, c, d
Eden, C.: Thickness diffusivity in the Southern Ocean, Geophys. Res. Lett., 33, L11606, https://doi.org/10.1029/2006GL026157, 2006. a
Elipot, S., Lumpkin, R., Perez, R. C., Lilly, J. M., Early, J. J., and Sykulski, A. M.: A global surface drifter data set at hourly resolution, J. Geophys. Res.-Oceans, 121, 2937–2966, https://doi.org/10.1002/2016JC011716, 2016. a
Ernst, P. A., Subrahmanyam, B., Trott, C. B., and Chaigneau, A.: Characteristics of submesoscale eddy structures within mesoscale eddies in the Gulf of Mexico from ° ECCO estimates, Frontiers in Marine Science, 10, 1181676, https://doi.org/10.3389/fmars.2023.1181676, 2023. a
ESR: OSCAR third degree resolution ocean surface currents, NASA Physical Oceanography Distributed Active Archive Center [data set], https://doi.org/10.5067/OSCAR-03D01, 2009. a, b
Ferrari, R. and Nikurashin, M.: Suppression of eddy mixing across jets in the Southern Ocean, J. Phys. Oceanogr., 40, 1501–1519, https://doi.org/10.1175/2010JPO4278.1, 2010. a
Griesel, A.: Particle Trajectories from 1/10 degree POP simulation in the Benguela upwelling region, Zenodo [data set], https://doi.org/10.5281/zenodo.13710842, 2024. a
Elipot, S., Sykulski, A., Lumpkin, R., Centurioni, L., and Pazos, M.: Hourly location, current velocity, and temperature collected from Global Drifter Program drifters world-wide, NOAA National Centers for Environmental Information [data set], https://doi.org/10.25921/x46c-3620, 2022. a
Griesel, A., Gille, S. T., Sprintall, J., McClean, J. L., LaCasce, J. H., and Maltrud, M. E.: Isopycnal diffusivities in the Antarctic circumpolar current inferred from Lagrangian floats in an eddying model, J. Geophys. Res.-Oceans, 115, C06006, https://doi.org/10.1029/2009JC005821, 2010. a, b, c, d
Griesel, A., McClean, M. J., Gille, S. T., Sprintall, J., and Eden, C.: Eulerian and Lagrangian isopycnal eddy diffusivities in the Southern Ocean from an eddying ocean model, J. Phys. Oceanogr., 44, 2191–2211, https://doi.org/10.1175/JPO-D-13-039.1, 2014. a, b, c, d
Griesel, A., Eden, C., Koopmann, N., and Yulaeva, E.: Comparing isopycnal eddy diffusivities in the Southern Ocean with predictions from linear theory, Ocean Model., 94, 33–45, https://doi.org/10.1016/j.ocemod.2015.08.001, 2015. a, b, c, d
Griesel, A., Dräger-Dietel, J., and Jochumsen, K.: Diagnosing and parameterizing the effects of oceanic eddies, in: Energy Transfers in Atmosphere and Ocean, edited by: Eden, C. and Iske, A., Mathematics of Planet Earth, Springer-Verlag, 193–224, https://doi.org/10.1007/978-3-030-05704-6_6, 2019. a, b
Haigh, M., Sun, L., Shevchenko, I., and Berloff, P.: Tracer-based estimates of eddy-induced diffusivities, Deep-Sea Res. Pt. I, 160, 103264, https://doi.org/10.1016/j.dsr.2020.103264, 2020. a, b
Hewitt, H. T., Roberts, M., Mathiot, P., Biastoch, A., Blockley, E., Chassignet, E. P., Fox-Kemper, B., Hyder, P., Marshall, D. P., Popova, E., Treguier, A.-M., Zanna, L., Yool, A., Yu, Y., Beadling, R., Bell, M., Kuhlbrodt, T., Arsouze, T., Bellucci, A., Castruccio, F., Gan, B., Putrasahan, D., Roberts, C. D., Van Roekel, L., and Zhang, Q.: Resolving and parameterising the ocean mesoscale in Earth System models, Current Climate Change Reports, 6, 137–152, https://doi.org/10.1007/s40641-020-00164-w, 2020. a
Hösen, E., Möller, J., Jochumsen, K., and Quadfasel, D.: Scales and properties of cold filaments in the Benguela upwelling system off Lüderitz, J. Geophys. Res.-Oceans, 121, 1896–1913, https://doi.org/10.1002/2015JC011411, 2016. a
Huot, P.-V., Kittel, C., Fichefet, T., Jourdain, N. C., and Fettweis, X.: Effects of ocean mesoscale eddies on atmosphere–sea ice–ocean interactions off Adélie Land, East Antarctica, Clim. Dynam., 59, 41–60, https://doi.org/10.1007/s00382-021-06115-x, 2022. a
Klocker, A., Ferrari, R., and LaCasce, J. H.: Estimating suppression of eddy mixing by mean flows, J. Phys. Oceanogr., 9, 1566–1576, https://doi.org/10.1175/JPO-D-11-0205.1, 2012a. a, b
Klocker, A., Ferrari, R., LaCasce, J. H., and Merrifield, S. T.: Reconciling float-based and tracer-based estimates of eddy diffusivities, J. Mar. Res., 70, 569–602, 2012b. a
Koszalka, I., Lacasce, J., and Orvik, K.: Relative dispersion in the Nordic Seas, J. Mar. Res., 67, 411–433, 2009. a
LaCasce, J. H., Ferrari, R., Marshall, J., Tulloch, R., Balwada, D., and Speer, K.: Statistics from Lagrangian observations, Prog. Oceanogr., 77, 1–29, https://doi.org/10.1016/j.pocean.2008.02.002, 2008. a, b, c
LaCasce, J. H., Ferrari, R., Marshall, J., Tulloch, R., Balwada, D., and Speer, K.: Float derived isopycnal diffusivities in the DIMES experiment, J. Phys. Oceanogr., 44, 764–780, https://doi.org/10.1175/JPO-D-13-0175.1, 2014. a
Large, W. G. and Danabasoglu, G.: Attribution and impacts of upper-ocean biases in CCSM3, J. Climate, 19, 2325–2346, https://doi.org/10.1175/JCLI3740.1, 2006. a
Large, W. G. and Yeager, S. G.: Diurnal to decadal global forcing for ocean and sea-ice models: the datasets and flux climatologies, NCAR Technical Note TN-460+STR, 8, National Center for Atmospheric Research, https://doi.org/10.5065/D6KK98Q6, 2004. a
Large, W. G. and Yeager, S. G.: The global climatology of an interannually varying air-sea flux data set, Clim. Dynam., 33, 341–364, https://doi.org/10.1007/s00382-008-0441-3, 2009. a
Lutjeharms, J.: The Agulhas Current, Springer Verlag Berlin-Heidelberg, https://doi.org/10.1007/3-540-37212-1, 2006. a
Maltrud, M. E., Bryan, F., and Peacock, S.: Boundary impulse response functions in a century-long eddying global ocean simulation, Environ. Fluid Mech., 10, 275–295, https://doi.org/10.1007/s10652-009-9154-3, 2010. a
Nakamura, N.: Two-Dimensional Mixing, Edge Formation, and Permeability Diagnosed in an Area Coordinate, J. Atmos. Sci., 53, 1524–1537, https://doi.org/10.1175/1520-0469(1996)053<1524:TDMEFA>2.0.CO;2, 1996. a
Ni, Q., Zhai, X., Wang, G., and Marshall, D. P.: Random movement of mesoscale eddies in the global ocean, J. Phys. Oceanogr., 50, 2341–2357, https://doi.org/10.1175/JPO-D-19-0192.1, 2020. a
North, R. P., Dräger-Dietel, J., and Griesel, A.: Characterization of physical properties of a coastal upwelling filament with evidence of enhanced submesoscale activity and transition from balanced to unbalanced motions in the Benguela upwelling region, Ocean Sci., 20, 103–121, https://doi.org/10.5194/os-20-103-2024, 2024. a, b
Oh, S. I., Zhurbas, V., and Park, W. S.: Estimating horizontal diffusivity in the East Sea (Sea of Japan) and the northwest Pacific from satellite-tracked drifter data, J. Geophys. Res.-Oceans, 105, 6483–6492, https://doi.org/10.1029/2000JC900002, 2000. a, b, c, d
Peng, J.-P., Holtermann, P., and Umlauf, L.: Frontal instability and energy dissipation in a submesoscale filament, J. Phys. Oceanogr., 50, 2017–2035, https://doi.org/10.1175/JPO-D-19-0270.1, 2020. a
Peng, S., Qian, Y.-K., Lumpkin, R., Li, P., Wang, D., and Du, Y.: Characteristics of the near-surface currents in the Indian Ocean as deduced from satellite-tracked surface drifters. Part II: Lagrangian statistics, J. Phys. Oceanogr., 45, 459–477, https://doi.org/10.1175/JPO-D-14-0049.1, 2015. a, b, c, d
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. a
Rühs, S., Zhurbas, V., Koszalka, I. M., Durgadoo, J. V., and Biastoch, A.: Eddy diffusivity estimates from lagrangian trajectories simulated with ocean models and surface drifter data – a case study for the greater agulhas system, J. Phys. Oceanogr., 48, 175–196, https://doi.org/10.1175/JPO-D-17-0048.1, 2018. a, b, c
Rypina, I. I., Kamenkovich, I., Berloff, P., and Pratt, L. J.: Eddy-induced particle dispersion in the near-surface North Atlantic, J. Phys. Oceanogr., 42, 2206–2228, https://doi.org/10.1175/JPO-D-11-0191.1, 2012. a, b, c
Sansòn, L. Z., Pèrez-Brunius, P., and Sheinbaum, J.: Surface relative dispersion in the southwestern Gulf of Mexico, J. Phys. Oceanogr., 47, 387–403, https://doi.org/10.1175/JPO-D-16-0105.1, 2017. a
Small, J. R., Churchister, E., Hedstrom, K., Kaufmann, B., and Large, W.: The Benguela upwelling system: quantifying the sensitivity to resolution and coastal wind representation in a global climate model, J. Climate, 28, 9409–9432, https://doi.org/10.1175/JCLI-D-15-0192.1, 2015. a
Stammer, D.: On eddy characteristics, eddy transports, and mean flow properties, J. Phys. Oceanogr., 28, 727–739, https://doi.org/10.1175/1520-0485(1998)028<0727:OECETA>2.0.CO;2, 1998. a
Sterl, M. F., LaCasce, J. H., Groeskamp, S., Nummelin, A., Isachsen, P., and Baatsen, M.: Suppression of mesoscale eddy mixing by topographic PV gradients, J. Phys. Oceanogr., 54, 1089–1103, https://doi.org/10.1175/JPO-D-23-0142.1, 2024. a
Taylor, G.: Diffusion by continuous movements, P. Lond. Math. Soc., 20, 196–212, https://doi.org/10.1112/plms/s2-20.1.196, 1921. a, b, c, d
Taylor, G.: Dispersion of soluble matter in solvent flowing slowly through a tube, P. Roy. Soc. A-Math. Phy., 219, 186–203, https://doi.org/10.1098/rspa.1953.0139, 1953. a, b, c
Zhang, W. and Wolfe, C.: Inferring tracer diffusivity from coherent mesoscale eddies, J. Adv. Model. Earth Sy., 16, 1–25, https://doi.org/10.1029/2023MS004004, 2024. a
Zhurbas, V., Lyzhkov, D., and Kuzmina, N.: Drifter-derived estimates of lateral eddy diffusivity in the World Ocean with emphasis on the Indian Ocean and problems of parameterization, Deep-Sea Res. Pt. I, 83, 1–11, https://doi.org/10.1016/j.dsr.2013.09.001, 2014. a, b
Short summary
The study explores how unresolved motions in the Benguela upwelling region affect diffusivity estimates and the need for full diffusivity tensors in models. Using a scalar for lateral mixing can be inaccurate due to directional mixing. Analysis of buoys and simulations shows that diffusivity from particle pairs is lower than expected and that removing the mean flow improves estimates. The study shows the importance of full diffusivity tensors for better model mixing and reducing warm biases in models.
The study explores how unresolved motions in the Benguela upwelling region affect diffusivity...