Momentum diffusivity equation

[michelincook]

1. Homework Statement

In your own words, explain momentum diffusivity (Km) and why it is important. From the above information and your knowledge of the momentum flux, calculate Km at 16 m height.[Hint: the equation to calculate Km requires only k, z and u*].


k=0.4
z=depth which would be 16m in this case
U*=friction velocity

i'm having trouble figuring out what equation I'm to use
thanks for the help

 

[jbsteele]

2. Homework Equations 3. The Attempt at a Solution Momentum diffusivity (Km) is the rate of transport of momentum in the vertical direction due to turbulence in the atmosphere. It is important because it helps us to understand how the momentum flux, or the exchange of momentum between the atmosphere and the surface of the earth, changes with altitude. Km can be calculated using the equation: Km=k*z/u*, where k is the turbulent kinetic energy, z is the height, and u* is the friction velocity. In this case, Km is calculated as 0.4*16/u*.