[CF-metadata] standard names for flag/qc variables

[Jonathan Gregory]

Dear Janet

> I have a flag/qc variable for each variable in my netcdf file.  I have
> found standard names for all of the regular variables, but I couldn't
> find any information on whether there are standard names for flag
> variables.  I saw _qc used in the section where flags_values was
> discussed, but using this doesn't allow my netcdf file to pass the
> cf-compliance-checker.  It says that eastward_wind_qc is an invalid
> standard name.  Any suggestions on what to name these flag/qc variables?

Your quality flag variable is an ancillary data variable, and its standard_name
attribute should be "eastward_wind status_flag". If you wish, you can point to
it from the eastward_wind data variable using an ancillary_variables attribute.
See CF 3.4.

Best wishes

Jonathan