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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?

  • Chouksey, A., Griesel, A., Chouksey, M. & Eden, C. (2022). Changes in global ocean circulation due to isopycnal diffusion. J. Phys. Oceanogr. 52(9), 2219-2235, doi: https://doi.org/10.1175/JPO-D-21-0205.1. 

  • Kumar, A., Brüggemann, N., Smith, R., & Marotzke, J. (2022). Response of a tropical cyclone to a subsurface ocean eddy and the role of boundary layer dynamics. Q.J.R. Meteorol. Soc. 148, 378-402, doi: https://doi.org/10.1002/qj.4210. 

  • Peng, J.-P., Dräger-Dietel, J., North, R. P., & Umlauf, L. (2021). Diurnal Variability of Frontal Dynamics, Instability, and Turbulence in a Submesoscale Upwelling Filament, J. Phys.Oceanogr. 51(9), 2825-2843, doi: https://doi.org/10.1175/JPO-D-21-0033.1.

  • Sidorenko, D., Danilov, S., Streffing, J., Juricke, S., Jung, T., Koldunov, N. et al. (2021). AMOC variability and watermass transformations in the AWI climate model. J. Adv. Model Earth Sy. 13, e2021MS002582, doi: https://doi.org/10.1029/2021MS002582.

  • Mohamad, H. & Oliver, M. (2021). Numerical integration of functions of a rapidly rotating phase. SIAM J. Num. Anal. 59, 2310–2319, doi: https://doi.org/10.1137/19M128658X.

  • Li, Q., Bruggemann, J., Burchard, H., Klingbeil, K., Umlauf, L. & Bolding, K. (2021). Integrating CVMix into GOTM (v6.0): a consistent framework for testing, comparing, and applying ocean mixing schemes. Geosci. Model Dev., doi: https://doi.org/10.5194/gmd-14-4261-2021.

  • Carpenter, J. R. , Rodrigues, A., Schultze, L. K. P., Merckelbach, L. M., Suzuki, N., Baschek, B. & Umlauf, L. (2020). Shear Instability and Turbulence Within a Submesoscale Front Following a Storm. Geophys. Res. Lett., doi: https://doi.org/10.1029/2020GL090365.

  • Li, Z. & von Storch, J.-S. (2020). M2 internal-tide generation in STORMTIDE2. J. Geophys. Res. - Oceans 125, e2019JC01545, doi: https://doi.org/10.1029/2019JC015453.

  • Masur, G. T., & Oliver, M. (2020). Optimal balance for rotating shallow water in primitive variables, Geophys. & Astrophys. Fluid Dyn., doi: https://doi.org/10.1080/03091929.2020.1745789.

  • Rackow, T., & Juricke, S (2019). Flow‐dependent stochastic coupling for climate models with high ocean‐to‐atmosphere resolution ratio. Q. J. Roy. Meteor. Soc., 1-17, https://doi.org/10.1002/qj.3674.