Rescale the regridded quantities. Not using a rescaling can lead to bad results if the
ratio of the grid spacings is large. The default is to rescale by the 2-norm of the quantity
except for generic interpolations (i.e. between curvilinear or non-commensurate grids).
Options:
scale_none:
Do not rescale the regridded quantities.
scale_norm2:
Scale the regridded quantities by the 2-norm of the quantity on the overlapping
region of the grid.