Visualising the Southern Ocean

This animation by Isa Rosso and Andy Hogg, developed with the help of Stuart Ramsden of the National Computational Infrastructure’s VizLab, has been derived from a numerical model that calculates how flows evolve in the ocean.

The spectacular flows revealed in this animation show what happens when winds and thermal forcing are applied to an ocean model  – just as happens in the real oceans. It shows the movement of the ocean in the form of turbulent flows that develop from changes in winds and temperature.

In the animation, this movement is seen from three different perspectives:

  • Sea-surface temperatures,
  • Velocity
  • Vorticity.

While sea surface temperatures and velocity are self explanatory, vorticity is less so. Vorticity is a measure of the rotation of the fluid. For example, water that rotates after we take the plug out of the sink would have high vorticity, indicating the presence of a vortex or eddy. You can find out more about vorticity here or through this fascinating video from the 1950s.

Vorticity, like sea surface temperatures and velocity, helps reveal the characteristics of turbulence and the amount of energy it contains.

Interestingly, turbulence by itself comprises a substantial amount of the ocean’s energy. For example the energy contained by turbulence in this animation is five to ten times more than the average energy in the strongest current in the ocean (Antarctic Circumpolar Current).

At the halfway point of the video, the animation zooms into an even smaller region. This allows us to see the turbulence at even smaller scales.

This close-up look is important for two reasons. In the first instance, it helps researchers understand the interaction of the different types of turbulence generated by wind and temperature.

But it also opens a window that will allow them to determine whether fine scale turbulence can help mix nutrients between different vertical layers in the ocean. This is important because this mixing may help contribute to phytoplankton blooms that can be seen in this area.

Knowing this will help researchers to understand the links between physical and biological processes in this part of the ocean.

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