NetCDF Operators (NCO)

metadata
Author

Sunny Hospital

Published

June 25, 2025

Useful nco commands

For full descriptions, check out the resource links.

nccopy

The nccopy compresses a netCDF file at various levels

usage: nccopy [-flag] [original nc filename] [compressed nc filename]

example nccopy -d4 largeFile.nc compressedFile.nc

options:

-d flag represents deflation level from 1 to 9 and is required.

Level 1 (faster compression) to Level 9 (smaller compression)

ncdump

The ncdump generates an ASCII representation (common data language) of a netCDF file.

usage: ncdump [-flag] [your nc filename] > [your output file]

example: ncdump -c input.nc > output.cdl

options: ncdump -h outputs the header info; same as -c but doesn’t include values

ncgen

The command reads the .cdl file and generates a NetCDF

usage: ncgen -o nc_file cdl_file

example:

ncgen -o output.nc input.cdl # specify an output file
   
ncgen -b input.cdl # caution, this overwites nc if it exists

ncgen -k4 -o output.nc imput.cdl # Output netCDF-4 classic model file

ncks

This command merges (appends with -A) the new attributes from metadata.nc file into your existing NetCDF file.

usage: nck -A filename1.nc filename2.nc

example: ncks -A metadata.nc mydata_file.nc

Resources

https://www.bic.mni.mcgill.ca/users/sean/Docs/netcdf/guide.txn_79.html

https://www.unidata.ucar.edu/software/netcdf/workshops/2011/utilities/NcgenExamples.html