GrADS command list :
A detail of GrADS commands can be found here :
$ grads # start GraDS
ga-> ! ls -ltr # use ! to send command to shell.
ga-> open model.ctl # open param description file
ga-> query file # see what is in this file
ga-> d ps # display
ga-> clear clears the display
ga-> c
ga-> set lon -90 sets longitude to 90 degrees West
ga-> set lat 40 sets latitude to 40 degrees North
ga-> set lev 500 sets level to 500 mb
ga-> set t 1 sets time to first time step
ga-> set lon -180 0 X is now a varying dimension
ga-> set lat 0 90
Note: from now on, "ga-> " is omitted.
c
set t 1 5
display (tsfc-273.16)*9/5+32
d sqrt(u*u+v*v) # conversion
d mag(u,v) # built-in function mag: magnitude of the wind
d ave(hgt,t=1,t=5) # built-in function ave :
d hgt-ave(hgt,x=1,x=72) # take means over longitude to remove the zonal mean:
d hgt(t=2) - hgt(t=1) # perform time differencing
The complete specification of a variable name is: name.file(dim +|-|= value, ...)
ga-> q files # check how many files are open.
File 1 : gfs.t12z.pgrb2.0p25.anl
Descriptor: gfs.t12z.pgrb2.0p25.anl.ctl
Binary: gfs.t12z.pgrb2.0p25.anl
File 2 : gfs.t12z.pgrb2.0p25.f000
Descriptor: gfs.t12z.pgrb2.0p25.f000.ctl
Binary: gfs.t12z.pgrb2.0p25.f000
ga-> set dfile 1 # set default file to file 1.
Default file set to: gfs.t12z.pgrb2.0p25.anl
ga-> q file # check to see what is in file 1.
display hgt.2 - hgt.1
d hcurl(u,v) # horizontal relative vorticity via finite differencing
d vint(ps,q,275) # a mass weighted vertical integral
set cint 30 # contour interval
set ccolor 3 # contour color
set csmooth on # apply a cubic smoother
# gxout : graphics output
set gxout shaded # alternate ways of displaying the data .
set gxout contour
draw title 500mb Heights and Vorticity # annotate title
set gxout vector # view wind vector
d u;v
