20000614: gdthgt and gvcord=hght

>From: weather <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200006141936.e5EJarT25468

>I am trying to produce a plot of 10 meter winds from the RUC2
>(I download the GEMPAK file fromm the NCEP server).  Why does this
>not produce a plot of barbs:
>
>GEMPAK-GDTHGT>l
> GPOINT   = 31.7;-95.7
> GDATTIM  = f000-f003
> GVCORD   = hght
> GFUNC    = 
> GVECT    = WND
> GDFILE   = $HDS/00061417_ruc2.gem
> PTYPE    = lin
> TAXIS    = 
> YAXIS    = 0/30/10
> BORDER   = 1
> LINE     = 3
> CINT     = 0
> WIND     = bk1
> TITLE    = 1
> CLEAR    = yes
> SCALE    = 0
> PANEL    = 1
> DEVICE   = xw
> TEXT     = 1
> 
> This works fine if I change gvcord to pres and yaxis to 1000/500/50.
> 
> HGHT is a valid vertical coordinate in this file and it contains 2m
> and 10m.  If i use gdtser and set gvcord=hght and gfunc=urel, I get
> output.
> 
> Any ideas?
> 
> Robert Mullenax
>

Robert,

Although the HGHT coordinate exists for 2m and 10m, U and V are only
at 1 single level (10m). Tmpc is on the 2m level.

The vector plotting portion of gdthgt uses a method to produce evenly spaced 
levels
on the output plot which requires data on at least 2 levels. So, as a result,
your plot will not display wind barbs (unless you use gddiag to create another
level with wind data).

GDTSER does not attempt to plot multiple levels, so there is not a problem in
needing at least 2 levels for display.


Steve Chiswell