Problem when slicing a NEMO 2d grid objects defined with dask chunks.

[lesommer]

a slice of a grid object defined with chunks appears to be disfunctionnal.

eg.

from oocgcm.oceanmodels.nemo import grids _grd = grids.nemo_2d_grid(...,chunks=xr_chunks) grd = _grd[500:1500,500:1500]

this works :

gssh = grd.horizontal_gradient(buoyancy)

but this raises an exception

ghb = grd.norm_of_vectorfield(grd.horizontal_gradient(buoyancy))