Peter Dennert

Interactions between low-mode internal tides and mesoscale eddies in the Walvis Ridge Region

Mixing processes in the ocean interiors play an important role in the global ocean circulation. A certain amount of mixing is necessary to maintain the stratification and balance the overturning circulation. Molecular diffusion of temperature and salinity on their own are too slow to fulfill the mixing, therefore turbulent motions are required. Such turbulence can be introduced over various ways but one of the most important routes is via internal tides. Internal tides are generated by the interaction of the bathymetry and barotropic tides which are directly induced by the tidal forcing on the waterbody. Depending on the bathymetric features the scales of the internal tides can vary. Small internal waves tend to dissipate close to their origin, the more energetic larger waves can travel over hundreds of kilometers across the ocean. As they travel they can interact with other bathymetry, waves or mesoscale eddies. Interactions range from scattering, reflection up to dissipation and are therefore crucial for the energy transport of the waves. A good understanding of internal tide propagation is crucial for better estimations of the regional dependence of mixing in the oceans.

During my PhD thesis I will study the internal wave field close to the Walvis Ridge in the souther Atlantic. The location features prominent bathymetric structure which lead to generation of large internal tides and a high activity of mesoscale eddies. By analyzing various types of observational data the goal is to find connections between these oceanographic features and gain a deeper understanding on the energy pathways in the region.

The project is part of the TRR181 „Energy Transfers in Atmosphere and Ocean“ in the subproject W2 Scattering and Refraction of Low-Mode Internal Tides by Interaction With Mesoscale Eddies and therefore in close cooperation with other subproject.