The impact of submesoscale mixing in the ocean

There has been much attention in recent years on oceanic eddies smaller than about 10 km, the so-called “submesoscale”. These eddies are important for vertical motion, bringing nutrients to the sea surface. Many believe they are also important for lateral stirring, which is an issue for dispersing pollutants like oil. But the observations are ambiguous, suggesting that lateral stirring is often dominated instead by large scale features.

In this project, we’ll look at lateral stirring in a simplified, two dimensional turbulence model. By using appropriate forcings, we’ll obtain both small and large scale eddies, and we’ll diagnose their relative importance for stirring by advecting numerical particles.

The project involves some theory (I’ll explain), numerical simulations and data analysis. Thus the student will obtain experience in all three areas. The work has direct relevance for the advection of oil, biological material and leaked radioactive material (see Figure).

It is also important when using satellite data (which typically does not resolve submesoscale eddies) for diagnosing lateral mixing.

Radioactive material spreading in the ocean after the meltdown of the Fukushima nuclear power plant in Japan. The material was eventually observed over much of the North Pacific, and impacted marine life. The large scale plume suggests advection by large eddies, rather than mixing at small scales.   
Published Sep. 5, 2018 2:05 PM - Last modified Sep. 5, 2018 2:05 PM


Scope (credits)