CDO

Output from ncdump:

@dimensions:
time = UNLIMITED ; // (120 currently)
x = 256 ;
y = 220 ;
vertices = 4 ;
x_2 = 256 ;
y_2 = 220 ;
x_3 = 256 ;
y_3 = 220 ;
depth = 40 ;
depth_2 = 41 ;

@

Output from verifygrid:

cdo verifygrid: Grid no 1 (of 3) consists of 56320 (256x220) cells (type: curvilinear), of which
cdo verifygrid: 56320 cells have 4 vertices
cdo verifygrid: 74 cells have duplicate vertices
cdo verifygrid: 440 cells are not unique
cdo verifygrid: 50 cells are non-convex
cdo verifygrid: 33 cells have their vertices arranged in a clockwise order
cdo verifygrid: 415 cells have their center point located outside their boundaries
cdo verifygrid: lon : -179.9865 to 179.9932 degrees
cdo verifygrid: lat : -83.96551 to 89.7266 degrees
cdo verifygrid: Grid no 2 (of 3) consists of 56320 (256x220) cells (type: curvilinear), of which
cdo verifygrid: 56064 cells have 4 vertices
cdo verifygrid: 256 cells have unusable vertices
cdo verifygrid: 440 cells are not unique
cdo verifygrid: 256 cells are non-convex
cdo verifygrid: lon_2 : -179.9654 to 179.9794 degrees
cdo verifygrid: lat_2 : -83.9661 to 89.8187 degrees
cdo verifygrid: Grid no 3 (of 3) consists of 56320 (256x220) cells (type: curvilinear), of which
cdo verifygrid: 255 cells have 3 vertices
cdo verifygrid: 56065 cells have 4 vertices
cdo verifygrid: 255 cells have duplicate vertices
cdo verifygrid: 440 cells are not unique
cdo verifygrid: 254 cells are non-convex
cdo verifygrid: 2 cells have their vertices arranged in a clockwise order
cdo verifygrid: 221 cells have their center point located outside their boundaries
cdo verifygrid: lon_3 : -179.9962 to 179.994 degrees
cdo verifygrid: lat_3 : -83.96551 to 89.78878 degrees

Data on a MPIOM model grid have 2 extra columns, which have to be removed before interpolation:

cdo remapbil,r360x180 -sethalo,-1,-1 infile outfile

Thank you - I tried removing those two columns following your instruction but now receive the following error message:

cdo(1) sethalo: Process started

cdo(1) sethalo (Abort): Too many different grids!

With this operator, all input fields must be on the same grid. If there is more than one grid, select the data on the desired grid with selgrid:

cdo remapbil,r360x180 -sethalo,-1,-1 -selgrid,1 infile outfile

Thank you for the assistance. Following your advice I used the following command:

cdo -L remapbil,r360x180 -sethalo,-1,-1 -selgrid,1 infile outfile

Regrettably I still get the undefined values at the boundaries (see attached file).

Could you please upload the data file?

Sure, thank you very much for the help. Please find attached the two files from:

cdo -L remapbil,r360x180 -sethalo,-1,-1 -selgrid,1 test.nc test2.nc

This seems to be a problem in the CDO version you are using. Since CDO version 2.2.0 this works without any problems.

Ok thank you - I will check. I was using version 2.1.1