[gradsusr] How can I get ther gxout barb to work

[Arlindo da Silva]

2010/7/24 João Teixeira <a38978 at ua.pt>

>
> Hi there,
> I made a script to calculate the geostrophic wind in a certain level, and
> fixed point off my grid (in attachment).
> Now I would like to make a fancy display off it, like wind barb's, but all
> I can display is a line graph...
> I already try to use set gxout barb and *set gxou**t tserbarb*, with out
> any success.
> Does anybody know how to get the graphic to work.
> The data is varying in time for a simgle point (1-D)
>

The problem is that "gxyt tserbarb" is only implemented for station data, it
apparently does not work for gridded data. However, the gr2stn() function
could be used to fake station data. For example,

open model
set level 200
set t 1 5
set gxout tsrbarb
d gr2stn(ua,-90,45);gr2stn(va,-90,45)

The gr2stn() function interpolates gridded data to the lon/lat point
(90W,45N in this example). Therefore, you may need to compute the
geostrophic wind on the whole grid before using this function, even if you
only need ug, vg on a single point.

If you are using the opengrads bundle distro, I'd write the a gsudf (an
expression function as a gs script) for ug, vg and use it in the expression

d gr2stn(ug(h),-90,45);gr2stn(vg(h),-90,45)

You can can find out more about gsudf's here:

      http://opengrads.org/doc/udxt/gsudf/

It would have been far more convenient if 'gxout tserbarb' worked for
gridded data.

  Good Luck,

    Arlindo


Thanks
>
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-- 
Arlindo da Silva
dasilva at alum.mit.edu
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