Basic Concept of Operation
openopen or make available to grads a data file with either gridded or station data
ddisplay a GrADS "expression" (e.g., a slice of data)
setmanipulate the "what" "where" and "how" of data display
The GrADS "expression," or what you want to look at, can be as
simple as a variable in the data file that was opened, e.g.,
slp or an arithmetic or GrADS function operation on the data,
d slp/100 or
d mag(u,v) where mag is a GrADS intrinsic
The "where" of data display is called the "dimension environment"
and defines which part, chunk or "hyperslab" of the 5-D
geophysical space (lon,lat,level,time,ens) is displayed. The
dimension environment is manipulated through the set command and
is controlled in either grid coordinates (x,y,z,t,e indices) or world coordinates (
lon, lat, lev, time, ens).
The "what" and "how" of display is also controlled by the
set command and
includes both graphics methods (e.g., contours, streamlines) and
d to a file).
In addition, GrADS includes graphic primitives (e.g., lines and
circles) and basic labelling through the