Section: 4.4 NCL Utilities

4.4 NCL Utilities

NCL (NCAR Command Language) is an interpreted programming language for scientific data analysis and visualization that comes with many useful built-in functions and procedures for processing and manipulating data, including climate data and model output in netCDF, GRIB, and HDF formats.

In addition to the highly customizable, publication quality graphics that NCL can generate, its interactive scripting language and utilities can perform various useful operations on netCDF data.

Features include:

Ability to read and write netCDF-3, netCDF-4 classic, HDF4, binary, and ASCII data
Ability to read HDF-EOS2, GRIB1, and GRIB2 data
A utility ncl_filedump that prints the contents of supported files, including netCDF, HDF, GRIB1, GRIB2, HDF-EOS2.)
A utility ncl_convert2nc that converts one or more GRIB1, GRIB2, HDF and/or HDF-EOS files to netCDF.
Interactive interpretation of commands or batch mode for scripts
Over 600 functions and procedures for analysis, processing, and manipulating data arrays
Ability to call external C and Fortran routines

NCL Examples

Open a netCDF file called "ex_uv300.nc" as read-only and extract a variable named "U" as a data object with all its values and attributes:

     a = addfile("ex01B1_uv300.hs.nc","r")  ; open the file
     U = a->U                               ; import variable with metadata

NetCDF-4 note: NCL can read and write netCDF-4 data that uses the classic model.

2008 Unidata NetCDF Workshop for Developers and Data Providers > NetCDF Utilities