Ocean mixing and turbulence

Question 1

Define diffusion.

What is diffusivity in terms of turbulence?

Answer 1

Spreading. It is the net movement of something spreading from a higher concentration to a lower concentration. Diffusion is driven by a gradient in concentration.

Diffusivity is the mixing coefficient.
K - 10^-7 m^2/s

Question 2

Define gradient

Answer 2

A gradient is the change in the value of a quantity, for example, concentration, pressure, or temperature with the change in another variable, usually distance.

Question 3

1. What does it mean that turbulence is “dissipative”?

2. What are energy sources for ocean turbulence?

Answer 3

If energy is not put into the system, then the system dies out.

Energy sources:

• Tides
• Winds

Question 4

Draw and explain the terms

• Isopycnal
• Diapycnal

Answer 4

• Isopycnal: ALONG surfaces with constant density

* Diapycnal: ACROSS surfaces with constant density

Question 5

What is diabatic mixing

Answer 5

Mixing where heat is exchanged with the environment

Question 6

If you have a system with two fluids with different densities, what happens with the PE when the fluids are mixed?

Answer 6

Mixing increases the potential energy PE of the system.

Question 7

Mention some of the turbulent fluxes

Answer 7

• Heat
• Salt
• Density
• Buoyancy

Question 8

What is the Richardson nr; Ri

Answer 8

Richardson number tells about the relationship between N^2/S^2. The stratification (Brun-Vaiisala freq.) divided by the shear.

Ri = 0,25