vector/z=300:900/ . . . v, w
plots vectors below 900 m. PPL WINDOW,OFF seems to be causing it, but I thought the z range is sufficient to prevent it. (If the z range is ignored, vectors should be plotted all the way down to the bottom, which is at 6000 m.)
A sample script, the data file, and a sample plot are attached. (It's actually an extension of the same script I showed a few days ago.)
set mode grat:dash
let fac = 1e3 ! velocity-length scale
define symbol y1_ 30S
define symbol y2_ 28S
let z2_ = 900
!-------
!go init-print
let samp_vec_in_ = 0.45
let samp_vec_ = fac/200
vector/aspect/hlimits=($y1_):($y2_)/vlimits=0:`z2_`:50/color=red\
/y=($y1_):($y2_)/z=0:100/set mv,mw
ppl WINDOW,OFF
ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector,2,3
vector/aspect/nolabel/color=blue\
/y=($y1_):($y2_)/z=94:300/OVER/set mv,mw
ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector/ov,2,1
vector/aspect/nolabel/color=red\
/y=($y1_):($y2_)/z=300:`z2_`/OVER/set mv,mw
ppl vecset,`samp_vec_in_`,`samp_vec_`
ppl vector/ov,2,1
!go finish-print try-vector-overlay 3 false