NCAR Command Language (NCL) Data Access, Analysis, and Visualization Programming Language
Entry ID: NCAR_NGWWW
Abstract: The NCAR Command Language (NCL) is a programming language designed specifically for the access, analysis, and visualization of data. NCL can be run in interactive mode, where each line is interpreted as it is entered at your workstation, or it can be run in batch mode as an interpreter of complete scripts.
The power and utility of the language are evident in three areas:
- file input and output
- ... data processing
- graphical display
NCL has many features common to modern programming languages, including types, variables, operators, expressions, conditional statements, loops, and functions and procedures.
In addition to common programming features, NCL also has features that are not found in other programming languages, including features that handle the manipulation of metadata, the configuration of the output graphics, the import of data from a variety of data formats, and an algebra that supports array operations.
NCL comes with many useful built-in functions and procedures for processing and manipulating data. There are over 400 functions and procedures that include routines for:
- use specifically with climate and model data
- computing empirical orthogonal functions, Fourier coefficients, singular
value decomposition, averages,
- standard deviations, sin, cosine, log, min, max, etc.
- retrieving and converting date information
- drawing primitives (lines, filled areas, and markers), wind barbs, weather
map symbols, isosurfaces, and graphical objects
- file handling
- 1-dimensional, 2-dimensional, and 3-dimensional interpolation, approximation,
- facilitating computer analysis of scalar and vector global geophysical
quantities (most are based on the package known as Spherepack)
- retrieving environment variables and executing system commands
- NCL supports calling C and Fortran external routines, which makes NCL
- NCL uses several other publicly-available software packages for some of its
file I/O and data processing routines.
- These software packages include:
- HDF - a physical file format for storing scientific data
- LAPACK - a library of Fortran 77 subroutines for solving the most commonly
occurring problems in numerical linear algebra
- netCDF - a machine-independent format for representing scientific data (also,
an interface for array-oriented data access and a library that provides an
implementation of the interface)
- Spherepack - a collection of Fortran programs that facilitates computer
modeling of geophysical processes
[Summary provided by NCAR/NCL.]
Access Constraints To freely access, download, and use NCL, you must:
1. Agree to the NCL License.
2. Fill out and submit a short registration form. You need to at least fill in
the name, site, and email address fields.
3. Download the desired binaries.
4. Install the binaries on your system.
Creation and Review Dates