Dataset problem: Issues with hybrid pressure coordinate of CNRM models (CMIP6)

[schlunma]

Describe the dataset issue
The necessary attribute forumula_terms is not given (only formula_term, which is also incorrect for the bounds). Bounds of ap and b not set (see #536). Bounds of ap have wrong shape (2, ...) instead of (..., 2). Units of ap are not given (must be Pa). Bounds of latitude and longitude are missing.

• Data file has been changed by you in any way
• Project (CMIP5/CMIP6/OBS/obs4mips/etc): CMIP6
• Full dataset description (fill out as many as you know, please):
  • dataset: CNRM-CM6-1, CNRM-CM6-1-HR, CNRM-ESM2-1
  • experiment: historical
  • mip: Amon
  • grid:gr
  • variable used: cl
• Pointer to existing copy of data on ESGF node (it would be very useful if you could provide a physical fullpath to the file(s) that are causing the problem, e.g. on CEDA Jasmin or DKRZ):
  /mnt/lustre02/work/bd0854/DATA/ESMValTool2/CMIP6_DKRZ/CMIP/CNRM-CERFACS/CNRM-CM6-1/historical/r1i1p1f2/Amon/cl/gr/v20180917/cl_Amon_CNRM-CM6-1_historical_r1i1p1f2_gr_195001-201412.nc
/mnt/lustre02/work/bd0854/DATA/ESMValTool2/CMIP6_DKRZ/CMIP/CNRM-CERFACS/CNRM-CM6-1-HR/historical/r1i1p1f2/Amon/cl/gr/v20191021/cl_Amon_CNRM-CM6-1-HR_historical_r1i1p1f2_gr_200001-201412.nc
/mnt/lustre02/work/bd0854/DATA/ESMValTool2/CMIP6_DKRZ/CMIP/CNRM-CERFACS/CNRM-ESM2-1/historical/r1i1p1f2/Amon/cl/gr/v20181206/cl_Amon_CNRM-ESM2-1_historical_r1i1p1f2_gr_195001-201412.nc

ncdump (for CNRM-CM6-1, without global attributes):

netcdf cl_Amon_CNRM-CM6-1_historical_r1i1p1f2_gr_195001-201412 {
dimensions:
        lat = 128 ;
        lon = 256 ;
        lev = 91 ;
        axis_nbounds = 2 ;
        time = UNLIMITED ; // (780 currently)
        bnds = 2 ;
variables:
        double lat(lat) ;
                lat:axis = "Y" ;
                lat:standard_name = "latitude" ;
                lat:long_name = "Latitude" ;
                lat:units = "degrees_north" ;
        double lon(lon) ;
                lon:axis = "X" ;
                lon:standard_name = "longitude" ;
                lon:long_name = "Longitude" ;
                lon:units = "degrees_east" ;
        double lev(lev) ;
                lev:name = "lev" ;
                lev:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ;
                lev:long_name = "atmospheric model level" ;
                lev:units = "1" ;
                lev:positive = "down" ;
                lev:formula = "p = ap + b*ps" ;
                lev:formula_term = "ap: ap b: b ps: ps" ;
                lev:bounds = "lev_bounds" ;
        double lev_bounds(lev, axis_nbounds) ;
                lev_bounds:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ;
                lev_bounds:units = "1" ;
                lev_bounds:formula = "p = ap + b*ps" ;
                lev_bounds:formula_term = "ap: ap b: b ps: ps" ;
        double time(time) ;
                time:axis = "T" ;
                time:standard_name = "time" ;
                time:long_name = "Time axis" ;
                time:calendar = "gregorian" ;
                time:units = "days since 1850-01-01 00:00:00" ;
                time:time_origin = "1850-01-01 00:00:00" ;
                time:bounds = "time_bounds" ;
        double time_bounds(time, axis_nbounds) ;
        float cl(time, lev, lat, lon) ;
                cl:long_name = "Cloud Area Fraction" ;
                cl:units = "%" ;
                cl:online_operation = "average" ;
                cl:cell_methods = "area: time: mean" ;
                cl:interval_operation = "900 s" ;
                cl:interval_write = "1 month" ;
                cl:_FillValue = 1.e+20f ;
                cl:missing_value = 1.e+20f ;
                cl:coordinates = "" ;
                cl:standard_name = "cloud_area_fraction_in_atmosphere_layer" ;
                cl:description = "Includes both large-scale and convective cloud." ;
                cl:history = "none" ;
                cl:cell_measures = "area: areacella" ;
        float ps(time, lat, lon) ;
                ps:long_name = "Surface Air Pressure" ;
                ps:units = "Pa" ;
                ps:online_operation = "average" ;
                ps:cell_methods = "area: time: mean" ;
                ps:interval_operation = "900 s" ;
                ps:interval_write = "1 month" ;
                ps:_FillValue = 1.e+20f ;
                ps:missing_value = 1.e+20f ;
                ps:coordinates = "" ;
                ps:standard_name = "surface_air_pressure" ;
                ps:description = "not, in general, the same as mean sea-level pressure" ;
                ps:history = "none" ;
                ps:cell_measures = "area: areacella" ;
        double ap(lev) ;
                ap:long_name = "vertical coordinate formula term: ap(k)" ;
                ap:online_operation = "once" ;
                ap:coordinates = "" ;
        double b(lev) ;
                b:long_name = "vertical coordinate formula term: b(k)" ;
                b:online_operation = "once" ;
                b:coordinates = "" ;
        double b_bnds(bnds, lev) ;
                b_bnds:long_name = "vertical coordinate formula term: b(k+1/2)" ;
                b_bnds:online_operation = "once" ;
                b_bnds:coordinates = "" ;
        double ap_bnds(bnds, lev) ;
                ap_bnds:long_name = "vertical coordinate formula term: ap(k+1/2)" ;
                ap_bnds:online_operation = "once" ;
                ap_bnds:coordinates = "" ;

Fix provided in #529.

[schlunma]

Fix for this exists. I am 99% sure that this data will not be fixed on ESGF (we are approaching CMIP7), so I am closing this now.