External Utilities

bufrscan
gribmap
gribscan
grib2scan
gxeps
gxps
gxtran
stnmap

Expressions

Operators are:

+    Addition 
-    Subtraction 
*    Multiplication 
/    Division

exp

exp(expr)

Performs the e**x operation, where expr is x. Works on both gridded and station data.

exec

exec file-name <arg0 arg1...arg9>

file-name      the name of a file containing grads commands

grads | gradsdap    

gradsc | gradsnc | gradshdf | gradsdods   

GrADS is an interactive desktop tool for the analysis and display of earth science data. GrADS is used worldwide andfreely available over the internet.

GrADS implements two data models: a 5-Dimensional gridded data model, and a station data model. In the gridded data model, the dimensions are presumed to be latitude, longitude, level, time, and ensemble. In the station data model, data exist at arbitrary locations in space and time. Four dimensions (longitude, latitude, level, and time) are used as a framework in the station data model to guide which station reports are to be examined. Each data set is placed within a 4- or 5-Dimensional space by the use of a data descriptor file. Both gridded and station data may be described. Gridded data may be non-linearly spaced; gaussian grids and variable resolution ocean model grids are directly supported. The internal data format in a file may be binary, GRIB1, GRIB2, BUFR, NetCDF, HDF4-SDS, or HDF5.

The Ensemble Dimension

Ensemble Handling in grads

The EDEF entry in a descriptor file 

How to organize the data

Example #1: Lag Ensembles

Example #2: Retrospective Daily Hindcasts from CFS

Example #3: Ensembles with Different Lengths and Start Times in Binary Format

set lat|lon|lev|time|ens

set lat|lon|lev|time|ens val1 <val2>

This set command sets one dimension of the dimension environment using world coordinates.

q ens

q ens

This command returns information about the ensemble dimension. For each ensemble member, the printout includes the index number, ensemble name, length (number of time steps), start time in date format, time axis index of start time, and grib2 codes, if present.

enable print

This command is obsolete beginning with grads version 2.1. It has been replaced by gxprint.

This command opens the output file fname that will contain the instructions in grads metacode format to create a hardcopy of the graphical display. Any existing contents of fname will be lost. The output file fname is referred to as a grads metafile.

eloop

eloop(expr)

The eloop function is similar to the tloop function. When displaying a grads expression (expr) with the E (Ensemble) dimension varying, the eloop function will evaluate the exprwith each designated ensemble member fixed, then reassemble the grids to obtain a final result that is E-varying. The eloop function is provided as a way to obtain E-varying results from functions or expressions that are unable to operate when E is a varying dimension.

set x|y|z|t|e

set x|y|z|t|e val1 <val2>

This sets one dimension of the dimension environment using grid coordinates. You may use whatever coordinates are convenient to you. Issuing set lon is equivalent to issuing set x, both set the x dimension. The difference is only the units you wish to use when entering the command.

When you enter just one value, that dimension is said to be "fixed". When you enter two values, that dimension is said to be "varying". The combination of fixed and varying dimensions defines the dimension environment.