CDO

Hi Ali,

without the data I can only guess that you have to merge the grid and the data file first to get a correct grid for your variable (see attribute coordinates).

cdo -f nc -merge gridfile.nc datafile.nc outfile.nc

-Karin

Hi Karin

Thanks a lot. The merge seems to be working. But wen I suue the remap command:

cdo -P 48 remap,era_griddes,weights_r2b06.nc outfile.nc latlon_out1.nc
cdo remap: Nearest neighbor weights from unstructured (491520) to lonlat (2880x1441) grid
cdo remap: Nearest neighbor weights from unstructured (163842) to lonlat (2880x1441) grid
cdo remap (Warning): Reference to horizontal grid not available!

cdo remap (Abort): Reference to source grid not found!

Any idea what is happening here? I put the grid and the generic output file in the following link:

https://bwsyncandshare.kit.edu/dl/fiLPDK6GpjQRphwCbAmTAsGM/.zip

thanks again
Ali

The ouput_r2b06.nc file is written by NCL. You have to write the data in your NCL script more detailed (correct dimesnion names).

See [[http://ncl.ucar.edu/Applications/method_2.shtml]]

You have to name the dimensions in your data file correct. ncl3 seems to be ncells and ncl1 could be time, but this is what you should know.

-Karin

To change the dimension names you can use also NCO's ncrename program:

assuming ncl1 = time, ncl2 = levels and ncl3 = ncells

ncrename -d ncl1,time -v ncl1,time -d ncl2,levels -v ncl2,levels -d ncl3,ncells -v ncl3,ncells infile outfile

You have to add the coordinates attribute to your variable, too:

ncatted -a coordinates,AOD_DUST,a,c,"clon clat" infile outfile

But it is always a good style and idea to write your NCL script in the correct way.

-Karin

Hi Karin,

thanks a lot for the detailed explanations. I will work on this and get back to this QA if there were any issues.

enjoy the holidays
Ali

Dear Karin,

I am back to this issue and still have the same problems. The files are created by my colleague using NCL so I cannot change the sources anymore. The dimensions are ncl1 = levels, ncl2 = time and ncl3 = ncells. I corrected these dimension names and followed your instructions but still have the following error:

cdo remap: Nearest neighbor weights from unstructured (491520) to lonlat (2880x1441) grid
cdo remap: Nearest neighbor weights from unstructured (163842) to lonlat (2880x1441) grid
cdo remap (Warning): Reference to horizontal grid not available!

cdo remap (Abort): Reference to source grid not found!

Did you use the data I shared with you? Did it work for you?

thanks in advance
Ali

Hi Ali,

there is nothing else for it but to get the NCL script and modify it to get the right results. In the data file output_r2b06.nc not only the dimensions are incorrect named but also the time and levels variables are missing. By the way the dimensions are not in the correct order (time first), too.

-Karin