QBO nudging on arbitrary grids

[fvitt]

What is the feature/what would you like to discuss?

For lower resolution WACCM simulations it is advantageous to nudge the QBO. The ability to nudge the QBO when running WACCM on arbitrary grids (structured or unstructured) is desired. The zonal mean fields needed for the nudging scheme could use the Zonal_Mean code proposed in PR #629 which computes zonal mean values for arbitrary grids based on m=0 spherical harmonics.

Is there anyone in particular you want to be part of this conversation?

@dan800 @nadavis-ncar

Will this change (regression test) answers?

No

Will you be implementing this enhancement yourself?

Yes