CMIP6 IPSL-CM6A-LR netCDFs are unreadable

[davemfish]

I'm not able to read these netCDFs using xarray.

There's a related discussion here:
h5netcdf/h5netcdf#94

Although the file in question there looks essentially the same as ours, I found that xarray could not open the file using engine='netcdf4' either.

For now, this IPSL-CM6A-LR model will simply not be available to the downscaling workflow. But at any point we could debug further and likely find a way to read the data from this model. At that point, we would need to re-run scripts/rechunk_to_zarr_cmip6.py