External Utilities
exp(expr)
Performs the e**x
operation, where expr
is x
. Works on both gridded and station data.
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.
set lat|lon|lev|time|ens val1 <val2>
This set command sets one dimension of the dimension environment using world coordinates.
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.
This command is obsolete beginning with grads version 2.1. It has been replaced by gxprint
.
enable print fname
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(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 expr
with 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 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.