# 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.

## Objectives

### 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?

## Publications

**Badin, G.**, Behrens, J.,**Franzke, C., Oliver, M., & Rademacher, J.**(2019). Introduction,*Geophysical & Astrophysical Fluid Dynamics, 113:5-6*, 425-427, DOI: 10.1080/03091929.2019.1655259Gutjahr, O., Putrasahan, D., Lohmann, K.,

**Jungclaus, J. H., von Storch, J. S., Brüggemann, N.**, Haak, H., & Stössel, A. (2019). Max Planck Institute Earth System Model (MPI-ESM1. 2) for High-Resolution Model Intercomparison Project (HighResMIP).*Geophys. Mod. Develop.*,*12*, 3241-3281, doi.org/10.5194/gmd-12-3241-2019.Conti, G. and

**G. Badin**(2019). Velocity statistics for point vortices in the local α-models of turbulence,*Geophysical and Astrophysical Fluid Dynamics*, doi:10.1080/03091929.2019.1572750**Griesel, A., Dräger-Dietel, J.**, & Jochumsen, K. (2019). Diagnosing and Parameterizing the Effects of Oceanic Eddies. In*Energy Transfers in Atmosphere and Ocean*(pp. 193-224). Springer, Cham.**von Storch, J. S., Badin, G., & Oliver, M.**(2019). The Interior Energy Pathway: Inertia-Gravity Wave Emission by Oceanic Flows. In*Energy Transfers in Atmosphere and Ocean*(pp. 53-85). Springer, Cham.**Franzke, C. L., Oliver, M., Rademacher, J. D., & Badin, G.**(2019). Multi-scale methods for geophysical flows. In*Energy Transfers in Atmosphere and Ocean*(pp. 1-51). Springer, Cham.Mohamad, H., and

**M. Oliver**(2019). A direct construction of a slow manifold for a semilinear wave equation of Klein–Gordon type.*Journal of Differential Equations*.**Badin, G., M. Oliver and S. Vasylkevych**(2018). Geometric Lagrangian averaged Euler-Boussinesq and Primitive Equations,*Journal of Physics A: Mathematical and Theoretical*, 51, 455501, doi:10.1088/1751-8121/aae1cb**Dräger-Dietel, J.**, Jochumsen, K.,**Griesel, A., and Badin, G.**(2018). Relative dispersion of surface drifters in the Benguela upwelling region.*Journal of Physical Oceanography*.**Badin,****G.**and Barry, A., (2018) Collapse of generalized Euler and surface quasi-geostrophic point-vortices, Physical Review E, 98, 023110, doi.org/10.1103/PhysRevE.98.023110