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Area L: Large-Scale and Balanced Processes

Both the large-scale currents and mesoscale eddies in the ocean are essentially quasi-geostrophically balanced in the horizontal and hydrostatically in the vertical. Area L focuses on those processes in the ocean.

Eddies in the ocean

Mesoscale eddies in the ocean, sometimes referred to as the oceanic equivalent of atmospheric storms, derive their energy from the large-scale flow mainly through baroclinic instability processes. These processes are parameterized in climate models with down-gradient parameterizations using eddy diffusivities. In geostrophic turbulence, eddies then tend to transfer their energy upscale in an inverse cascade. But ultimately, this energy has to be dissipated and it is largely unknown how and where.

Our scientists specifically assess one important pathway to dissipation, the spontaneous emission of gravity waves by the quasi-balanced flows, and analyze drifter and float data to estimate eddy production and Lagrangian mixing from observations, models and theory.

Specific research questions in Area L are:

  • How is the balanced flow dissipated in the ocean, and how important is the route to dissipation via spontaneous wave generation?
  • What are the limits and validities of the eddy diffusion model and how can we quantify and parameterize the effects of mesoscale eddies in an energy-consistent way?

  • Schmitt, M., Klingbeil, K., Shevchenko, R. & Umlauf, L. (2025). Three‐Dimensional Ocean Surface Layer Response to Atmospheric Cold Pools and Diurnal Heating in the Trade Wind Regime. Journal Of Geophysical Research Oceans, 130(8). https://doi.org/10.1029/2024jc022129

  • Oelerich, R., Gülk, B., Dräger-Dietel, J. & Griesel, A. (2025). An estimate of the eddy diffusivity tensor from observed and simulated Lagrangian trajectories in the Benguela Upwelling System. Ocean Science, 21(2), 727–747. https://doi.org/10.5194/os-21-727-2025

  • Pinner, O., Pollmann, F., Janout, M., Voet, G. & Kanzow, T. (2025). Internal-wave-induced dissipation rates in the Weddell Sea Bottom Water gravity current. Ocean Science, 21(2), 701–726. https://doi.org/10.5194/os-21-701-2025

  • Kunz L., Griesel A., Eden C., Duran R. & Sainte-Rose B. (2024): Transient Attracting Profiles in the Great Pacific Garbage Patch. Ocean Science, 20(6), 1611–1630, doi: https://doi.org/10.5194/os-20-1611-2024

  • Peng, J., Jones, N. L., Rayson, M. D., Schmitt, M., Umlauf, L., Whitwell, C., Keating, S. R., Shakespeare, C. J. & Ivey, G. N. (2025). Interactions Between Diurnal Warm Layers and Surface‐Layer Fronts. Journal Of Geophysical Research Oceans, 130(1). https://doi.org/10.1029/2024jc021380

  • Fedele, F., Chandre, C. , Horvat, M. & Žagar, N. (2024): Hamiltonian Lorenz-like models. Physica D: Nonlinear Phenomena, 134494. doi: https://doi.org/10.1016/j.physd.2024.134494

  • Brüggemann, N., Losch, M., Scholz, P., Pollmann, F., Danilov, S., Gutjahr, O., Jungclaus, J., Koldunov, N., Korn, P., Olbers, D., Eden, C. (2024). Parameterized Internal Wave Mixing in Three Ocean General Circulation Models. Journal of Advances in Modeling Earth Systems, 16, e2023MS003768. doi: https://doi.org/10.1029/2023MS003768

  • Neduhal, V., Žagar, N., Lunkeit, F., Polichtchouk, I. & Zaplotnik, Ž. (2024). Decomposition of the Horizontal Wind Divergence Associated With the Rossby, Mixed Rossby-Gravity, Inertia-Gravity, and Kelvin Waves on the Sphere. Journal of Geophysical Research: Atmospheres, 129, e2023JD040427, doi: https://doi.org/10.1029/2023JD040427. 

  • Oliver, M. & Tiofack Kenfack, M.A. (2024). Deterministic and stochastic surrogate models for a slowly driven fast oscillator. SIAM J. Appl. Dyn. Syst. 23(2), 1090-1107, doi: https://doi.org/10.1137/23M1602176. 

  • Schmitt, M., Pham, H.T., Sarkar, S., Klingbeil, K. & Umlauf, L. (2024). Diurnal warm layers in the ocean: energetics, non-dimensional scaling, and parameterization. J. Phys. Oceanogr. 54(4), 1037-1055, doi: https://doi.org/10.1175/JPO-D-23-0129.1.