Categories: Data Management, Software, Visualization
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The Grid Analysis and Display System (GrADS) is an interactive tools used for easy access, manipulation, and visualization of earth science data. The format of the data may be either binary, GRIB, NetCDF, or HDF-SDS (Scientific Data Sets). GrADS has been implemented worldwide on a variety of commonly used operating systems and is freely distributed over the Internet.
GrADS uses a 4-Dimensional data environment: longitude, latitude, vertical level, and time. Data sets are placed within the 4-D space by use of a data descriptor file. GrADS interprets station data as well as gridded data, and the grids may be regular, non-linearly spaced, gaussian, or of variable resolution. Data from different data sets may be graphically overlaid, with correct spatial and time registration. Operations are executed interactively by entering FORTRAN-like expressions at the command line. A rich set of built-in functions are provided, but users may also add their own functions as external routines written in any programming language.
The official, more in depth GrADS tutorial can be found at http://cola.gmu.edu/grads/gadoc/tutorial.html.
Before GrADS can be used, make sure X11 forwarding is enabled. This is done by using the -Y flag when starting your ssh session
$ ssh -Y firstname.lastname@example.org
To use GrADS into your environment, load the module.
$ module load grads $ grads
This will open the GrADS command line. To open the appropriate descriptor file (Example files can be found on the official tutorial’s website), run
ga-> open model.ctl
This will load the appropriate variable/data into the interpreter. To display a specific variable or datapoint, use the display (or d for shorthand) command
ga-> display ps
The result will look similar to this: