Calculating and plotting divergence and streamlines in isobaric levels

[louistse0305]

Hello,

I wonder if we can do vertical interpolation using the 3D divergence field, if not, is there any way to calculate divergence in isobaric levels in the raw unstructured grid?
Moreover, I found that the function "gsn_csm_streamline" supports 2D field for u and v, is it possible to plot streamlines using the raw unstructured grid?

Thank you