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NCO NetCDF Operators

The NCO toolkit manipulates and analyzes data stored in netCDF-accessible formats, including DAP, HDF4, and HDF5. It exploits the geophysical expressivity of many CF (Climate & Forecast) metadata conventions, the flexible description of physical dimensions translated by UDUnits, the network transparency of OPeNDAP, the storage features (e.g., compression, chunking, groups) of HDF (the Hierarchical Data Format), and many powerful mathematical and statistical algorithms of GSL (the GNU Scientific Library). NCO is fast, powerful, and free.

What is NCO?

The netCDF Operators (NCO) comprise a dozen standalone, command-line programs that take netCDF, HDF, and/or DAP files as input, then operate (e.g., derive new data, compute statistics, print, hyperslab, manipulate metadata) and output the results to screen or files in text, binary, or netCDF formats. NCO aids analysis of gridded scientific data. The shell-command style of NCO allows users to manipulate and analyze files interactively, or with expressive scripts that avoid some overhead of higher-level programming environments.

Traditional geoscience data analysis requires users to work with numerous flat (data in one level or namespace) files. In that paradigm instruments or models produce, and then repositories archive and distribute, and then researchers request and analyze, collections of flat files. NCO works well with that paradigm, yet it also embodies the necessary algorithms to transition geoscience data analysis from relying solely on traditional (or “flat”) datasets to allowing newer hierarchical (or “nested”) datasets.

Operator Full Name Examples
ncap2 netCDF Arithmetic Processor here
ncatted netCDF ATTribute EDitor here
ncbo netCDF Binary Operator here
ncclimo netCDF CLIMatOlogy Generator here
nces netCDF Ensemble Statistics here
ncecat netCDF Ensemble conCATenator here
ncflint netCDF FiLe INTerpolator here
ncks netCDF Kitchen Sink here
ncpdq netCDF Permute Dimensions Quickly, Pack Data Quietly here
ncra netCDF Record Averager here
ncrcat netCDF Record conCATenator here
ncremap netCDF REMAPer here
ncrename netCDF RENAMEer here
ncwa netCDF Weighted Averager here

How to Contribute: Volunteer, Endorse, or Donate

The NCO project homepage points to mailing lists, discussion forums, and instructions to make contributing easy.


NCO has been supported by volunteers and professionals since 1995. External support from DOE, NASA, and NSF has sustained development and addition of its most powerful features.