Question: the wind measurements made at 50 km around a weather...

The wind measurements made at 50 km around a weather station are the
following:
50 km to the east: size 10 m / s, direction 90º
50 km north: size 4 m / s, direction 120º
50 km to the west: size 8 m / s, direction 90º
50 km to the south: size 4 m / s, direction 60º

a) Calculate the wind divergence in this station.
(b) If, in the atmospheric boundary layer, whose thickness is 500 m, the
horizontal wind does not change with z and is zero on the surface, what is the
vertical wind speed at the top of the boundary layer? (The density of the air
in the boundary layer is considered constant)
c) Suppose that wind measurement errors are 10%. What is the mistake
maximum associated with calculating the horizontal divergence?
d) What can be concluded about accuracy in estimating vertical velocity
by this method?

Thanks for you help