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NCAR Command Language

This is the source code for the NCAR Command Language (NCL).

NCL is a scripting language for the analysis and visualization of climate and weather data.

  • Supports NetCDF, GRIB, HDF, HDF-EOS, and shapefile data formats
  • Has hundreds of built-in computational routines
  • Produces high-quality graphics

NCL is developed by the Computational and Information Systems Lab at the National Center for Atmospheric Research (NCAR).

NCAR is sponsored by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

Important announcement on the future of NCL

NCAR has made the decision to adopt Python as the scripting language platform of choice for future development of analysis and visualization tools. Please read this open letter to NCL users to understand what kind of impact this will have on the future of NCL.


The current version of NCL is 6.6.2, which can be installed via conda.

conda create -n ncl_stable -c conda-forge ncl
source activate ncl_stable

Documentation and support

Visit the NCL website for documentation, examples, support, and installation.

NCL source code tree

The top level NCL source code tree contains the following directories and files:

Directory Purpose
common/ Low-level library and fonts required by NCAR Graphics and NCL
config/ Configuration files for installation
external/ External libraries required by NCL
install/ Auxiliary files for installation
ncarg2d/ NCAR Graphics and GKS libraries and examples
ncarview/ NCGM-based applications and raster utilities
ngmath/ Interpolation libraries for 1D, 2D, and 3D data
ni/ NCL interpreter, HLU library, examples, color tables, GRIB2 code tables
Files Purpose Code of Conduct for NCL user community How to contribute to the NCL Project
Configure Configuration script for installation
LICENSE Apache 2.0 License Information about NCL
version version file
yMakefile Top level makefile

Bug reports and feature requests

Use the GitHub issue tracker to submit a bug or request a feature.

Citing NCL

Cite NCL using the following text:

<> The NCAR Command Language (Version 6.6.2) [Software]. (2019). Boulder, Colorado: UCAR/NCAR/CISL/TDD.

Update the NCL version and year as appropriate.


The NCAR Command Language (NCL) is a scripting language for the analysis and visualization of climate and weather data.



Code of conduct





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