[Bug]: AttributeError: ...multiple values for 'longitude'

[pochedls]

Not really a bug necessarily, but a behavior we should think about...

What versions of software are you using?

• Package Version: I'm on PR Add temporal utilities and averaging functionalities #107, but this likely affect main.

What are the steps to reproduce this issue?

fn = '/p/user_pub/climate_work/pochedley1/cesm2le/TS/b.e21.BSSP370smbb.f09_g17.LE2-1301.020.cam.h0.TS.209501-210012.nc'
ds = xcdat.open_dataset(fn)

AttributeError: cf_xarray can't wrap attribute 'dims' because there are multiple values for 'longitude'. There is no unique mapping from 'longitude' to a value in 'dims'.

ncdump -h /p/user_pub/climate_work/pochedley1/cesm2le/TS/b.e21.BSSP370smbb.f09_g17.LE2-1301.020.cam.h0.TS.209501-210012.nc

double zlon(zlon) ;
zlon:_FillValue = -900. ;
zlon:long_name = "longitude" ;
zlon:units = "degrees_east" ;
zlon:bounds = "zlon_bnds" ;

What happens? Any logs, error output, etc?

It seems that since both lon and zlon have long_name = "longitude" they conflict. zlon is used to denote zonal averaging.

What were you expecting to happen?

Maybe annoying side effects, but I want it to at least open the dataset.

Any other comments?

The ideas that come to mind:

• Maybe this could simply be opened with xarray - I think subsequent xcdat functionality would work - right?
• Try to detect this situation and deal with it. I think there is a good argument for not doing this (this is a pretty specific issue). I'd be curious if E3SM has this issue for some output.
• We could choose the coordinates to handle if data_var is populated (then we would know to use lon instead of zlon).

[tomvothecoder]

Related to #285