Ocean mixing refers to the process by which different water masses in the ocean mix together. This process is critical in determining the ocean's circulation and how it affects climate and ecosystems. In particular, the mixing of mesoscale (and submesoscale) eddies, as well as tidal mixing, has a significant impact on the Southern Ocean circulation.

Mesoscale eddies are swirling vortices of water that can span tens to hundreds of kilometers across the ocean. These eddies are generated by a combination of wind, thermohaline gradients, and ocean currents. They play a crucial role in transporting heat, nutrients, and carbon dioxide around the ocean, affecting global climate patterns.

Tidal mixing, on the other hand, is the process by which tidal currents cause water masses of different properties to mix together. Tidal mixing is particularly important in the Antarctic margin, where strong tides can drive significant mixing in the vicinity of ice, which eventually affects the large-scale ocean circulation.

Despite its importance, ocean mixing is a highly chaotic and complex process that is difficult to model and predict. However, it sometimes behaves in a systematic manner, that is one of the most exciting part of physical oceanography. Scientists are using a combination of high-resolution observations and computer simulations to better understand ocean mixing, including or parametrizing mesoscale and submesoscale eddies and tidal mixing in the Southern Ocean.