Grid Analysis and Display System (GrADS) is a tool for easy access, manipulation, and visualization of earth science data. GrADS has two data models for handling gridded and station data. GrADS supports many data file formats, including binary (stream or sequential), GRIB (version 1 and 2), NetCDF, HDF (version 4 and 5), and BUFR (for station data).

GrADS uses a 5-Dimensional data environment: the four conventional dimensions (longitude, latitude, vertical level, and time) plus an optional 5th dimension for grids that is generally implemented but designed to be used for ensembles. Data sets are placed within the 5-D space by use of a data descriptor file. GrADS handles grids that are regular, non-linearly spaced, gaussian, or of variable resolution. Data from different data sets may be graphically overlaid, with correct spatial and time registration.

Using GrADS

To use the GrADS graphical interface, user please refer to on how to get the X-windows before launching grads.

Then use the following commands to setup required environment variables for GrADS:

System GrADS version Command
HPC2015 2.0.2 module load grads

To run GrADS at X-windows, type the command: grads


Users can write your own GrADS functions that can be invoked GrADS expression facility. Please refer to the GrADS user guide for details on how to write User Defined Functions(UDFs). Be reminded to define the User Defined Function Table(UDFT) and put it under your home directory (~/EOF/udft.txt). Environment variable GAUDFT is already set up as ${HOME}/EOF/udft.txt.

Additional Information

GrADS Official Homepage:
GrADS Documentation