Schematic illustration of the lifecycle of internal waves using model output from the ECCO LLC4320 simulation. Colours are zonal currents (sides) and sea surface height (surface). Internal waves are generated by the interaction of the surface tide with the Mid-Atlantic Ridge. They propagate away from their generation site and interact with the irregular bathymetry of the ocean floor, other internal waves and with low frequency ocean currents, eventually dissipating their energy and leading to mixing.

Diapycnal mixing specifically refers to the mixing of properties across isopycnals, and can roughly be thought of a mechanism by which oceanic properties are redistributed in the vertical. It impacts not only the interior stratification of the ocean, but also the distributions of biological and chemical tracers. Though mixing occurs at scales that are relatively tiny, it is ubiquitous and has influence at global scales, setting the rate at which the deepest waters in the ocean are raised back to the surface.

Ocean mixing occurs at centimeter scales and smaller, where gradients in water properties such as temperature and salinity are erased by molecular diffusion. It is driven by processes, such as turbulence, that enhance density gradients by stirring, allowing molecular diffusivity to proceed more rapidly.

My research focusses on both the processes that lead to turbulent mixing, such as breaking internal gravity waves driven by the winds and tides; as well as the impacts of turbulent mixing on biological and chemical processes in the ocean. A few current projects are listed below:

  • The structure of internal waves over sloping topography;
  • The generation of superinertial coastal trapped waves;
  • The interaction of wind-generated near-inertial waves with mesoscale flows;
  • Double diffusion, salt fingering and lateral intrusions;
  • Turbulence and mixing in the Arctic;
  • Verifying the impacts and efficacy of ocean alkalinity enhancement on taking up atmospheric carbon dioxide;
  • Submesoscale processes, subduction and turbulence.