Horizontal momentum flux in the surface layer Given the question below, how would the kinematic momentum flux be at the surface layer?
For letter a, why would it be that way (positive, negative, or 0)?


Based on the answer below:
I’m not sure if I’ve done it correctly, but this is how I answered it based in your comment below.

First, I assumed that $\overline{u’w’}$ = $\overline{w’u’}$. So is this something like the mixing of horizontal momentum into areas of lower wind speed (as is the case in the surface layer)?
Instead of just giving you the answer to a textbook problem (which would make SE a version of Chegg that future students would use to cheat on homework), I'll guide you in getting an answer.

Which variable does $\overline{u'w'}$ affect most?
For that variable, identify the surface layer.
Imagine that you are on the line. If you go straight up (that is, $w'&gt;0$) what would the difference be between the $M$ traced out and the graphed $M$? What is the sign of $w' \times u'$?
Do the same as number 3, except start at the top and go down ($w'&lt;0$).