error from netCDF in cf.write

I am processing some CMIP6 data on Jasmin (making time-means). I get the following error. I realise that you probably need more background to diagnose it, but perhaps it's obvious from this much information? As a result of the error, the file is not properly written, just the start of it.

Thanks. Jonathan

Traceback (most recent call last):
  File "/home/users/jonathan/bin/grouptime", line 97, in <module>
    cf.write(n,ofile)
  File "/apps/jasmin/jaspy/miniforge_envs/jaspy3.12/mf3-25.3.0-3/envs/jaspy3.12-mf3-25.3.0-3-v20250704/lib/python3.12/site-packages/cfdm/read_write/write.py", line 826, in __new__
    netcdf.write(
  File "/apps/jasmin/jaspy/miniforge_envs/jaspy3.12/mf3-25.3.0-3/envs/jaspy3.12-mf3-25.3.0-3-v20250704/lib/python3.12/site-packages/cfdm/decorators.py", line 171, in verbose_override_wrapper
    return method_with_verbose_kwarg(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/apps/jasmin/jaspy/miniforge_envs/jaspy3.12/mf3-25.3.0-3/envs/jaspy3.12-mf3-25.3.0-3-v20250704/lib/python3.12/site-packages/cfdm/read_write/netcdf/netcdfwrite.py", line 5232, in write
    self._file_io_iteration(
  File "/apps/jasmin/jaspy/miniforge_envs/jaspy3.12/mf3-25.3.0-3/envs/jaspy3.12-mf3-25.3.0-3-v20250704/lib/python3.12/site-packages/cfdm/read_write/netcdf/netcdfwrite.py", line 5478, in _file_io_iteration
    self._write_global_attributes(fields)
  File "/apps/jasmin/jaspy/miniforge_envs/jaspy3.12/mf3-25.3.0-3/envs/jaspy3.12-mf3-25.3.0-3-v20250704/lib/python3.12/site-packages/cfdm/read_write/netcdf/netcdfwrite.py", line 4610, in _write_global_attributes
    g["netcdf"].setncattr(
  File "src/netCDF4/_netCDF4.pyx", line 3087, in netCDF4._netCDF4.Dataset.setncattr
  File "src/netCDF4/_netCDF4.pyx", line 1858, in netCDF4._netCDF4._set_att
  File "src/netCDF4/_netCDF4.pyx", line 6733, in netCDF4._netCDF4._strencode
UnicodeEncodeError: 'utf-8' codec can't encode characters in position 61-63: surrogates not allowed

Comience por cfdm/read_write/netcdf/netcdfwrite.py en _write_global_attributes y la llamada a netCDF4 Dataset.setncattr que se muestra en el traceback. Reproduzca cf.write en el entorno de Python indicado e identifique qué atributo global contiene los caracteres sustitutos no válidos. Se considera terminado cuando los datos afectados puedan escribirse sin el UnicodeEncodeError y el comportamiento esté cubierto por una prueba de regresión adecuada.