CDO

Hi. I am new to modelling and working with environmental layers. I am trying to merge several netcdf files of a variable (dissolved inorganic carbon) into one, getting a mean value of the variable at the same time. I used cdo to do this and made the following call:
cdo timmean -cat '*.nc' mean.nc
However, I get the following warning:
cdo(1) cat: Process started Warning (cdfScanVarAttr): NetCDF: Variable not found - >lat< Warning (cdfInqContents): Coordinates variable zc can't be assigned! cdo(1) cat: 0%Warning (cdfScanVarAttr): NetCDF: Variable not found - >lat< Warning (cdfInqContents): Coordinates variable zc can't be assigned! 100%Warning (cdfScanVarAttr): NetCDF: Variable not found - >lat< Warning (cdfInqContents): Coordinates variable zc can't be assigned! 100%cdo(1) cat: Processed 24306975 values from 3 variables over 305 timesteps. cdo timmean: Processed 24306975 values from 1 variable over 305 timesteps [0.53s 49MB].

I still get the output. But should I worry about the warnings?

The following is the ncdump output for one of the source files.
ncdump -h DIC_1.nc netcdf DIC_1 { dimensions: time = 64 ; k = 1 ; j = 253 ; i = 315 ; variables: float DIC ; DIC:puv__parameter = "http://vocab.nerc.ac.uk/collection/P01/current/CINCMOD1/" ; DIC:coordinates = "time zc latitude longitude lat lon" ; DIC:units = "mg C m-3" ; DIC:long_name = "Dissolved Inorganic Carbon" ; DIC:valid_range = 0.f, 1.e+35f ; DIC:missing_value = 1.e+35f ; DIC:_ChunkSizes = 1, 11, 598, 128 ; double time(time) ; time:units = "days since 1990-01-01 00:00:00 +10" ; time:long_name = "Time" ; time:standard_name = "time" ; time:coordinate_type = "time" ; time:puv__uom = "http://vocab.nerc.ac.uk/collection/P06/current/UTAA/" ; time:_ChunkSizes = 512 ; time:calendar = "gregorian" ; time:_CoordinateAxisType = "Time" ; double zc(k) ; zc:units = "m" ; zc:positive = "up" ; zc:long_name = "Z coordinate" ; zc:axis = "Z" ; zc:coordinate_type = "Z" ; zc:_CoordinateAxisType = "Height" ; zc:_CoordinateZisPositive = "up" ; double latitude(j, i) ; latitude:units = "degrees_north" ; latitude:long_name = "Latitude" ; latitude:standard_name = "latitude" ; latitude:coordinate_type = "latitude" ; latitude:projection = "geographic" ; latitude:puv__ofProperty = "http://vocab.nerc.ac.uk/collection/S06/current/S0600045/" ; latitude:puv__uom = "http://vocab.nerc.ac.uk/collection/P06/current/DEGN/" ; latitude:_CoordinateAxisType = "Lat" ; double longitude(j, i) ; longitude:puv__uom = "http://vocab.nerc.ac.uk/collection/P06/current/DEGE/" ; longitude:units = "degrees_east" ; longitude:long_name = "Longitude" ; longitude:standard_name = "longitude" ; longitude:coordinate_type = "longitude" ; longitude:projection = "geographic" ; longitude:_CoordinateAxisType = "Lon" ; // global attributes: :title = "GBR1_H2p0_B3p2_Cfur_Dnrt" ; :description = "eReefs GBR 1k grid with rivers. Uses JCU bathy (www.deepreef.org). Created by JA 08.05.2012. hydrodynamic 2.0 BGC 3.2 cathment constant concentrations." ; :paramhead = "eReefs 1 km grid. Mile Furnas Catchment constant concentrations. More details of naming protocol at: eReefs.info." ; :paramfile = "./tran/gbr1_bgc_nrt.tran" ; :ems_version = "v1.4.0 rev(7358)" ; :date_created = "Thu Jun 22 15:14:52 2023" ; :Conventions = "CF-1.0" ; :Run_ID = "2.0" ; :Run_code = "GBR1_H2p0_B3p2_Cfur_Dnrt|G0.00|H0.00|S0.0|B2.0" ; :Parameter_File_Revision = "$Revision: 1945 $" ; :bald__isPrefixedBy = "prefix_list" ; :prefix_list_puv__ = "https://w3id.org/env/puv#" ; :prefix_list_qudt__ = "http://qudt.org/vocab/unit/" ; :History = "Translated to CF-1.0 Conventions by Netcdf-Java CDM (CFGridWriter2)\n", "Original Dataset = file:fx3/GBR1_H2p0_B3p2_Cfur_Dnrt.ncml; Translation Date = 2023-06-28T06:23:38.428Z" ; :geospatial_lat_min = -25.168796 ; :geospatial_lat_max = -22.15316 ; :geospatial_lon_min = 150.22234 ; :geospatial_lon_max = 153.761098 ; }