[gradsusr] Interpolation/point values

Stephen McMillan smcmillan at planalytics.com
Thu Mar 25 22:23:52 EDT 2010


Hello Steve,
You should be able to use gr2stn to get what you want.  First, set x and y
to fixed (z and/or t must be fixed), set gxout print, display gr2stn(...,
then capture the result.  For example, using the GFS ugrdprs and vgrdprs
variables and a single timestep:
'set x 1';'set y 1';'set lev 1000'
'set t 5'
'set gxout print'
'set prnopts %0.2f'
'd 1.944*gr2stn(mag(ugrdprs,vgrdprs),-73.27,39.5)';#output in knots
ws=sublin(result,3)
say 'Wnd spd = 'ws
Above is for a fixed timestep, but you could increment or vary t (lev) to
get multiple time (level) results.

Good luck--
Stephen McMillan

On Thu, Mar 25, 2010 at 4:55 PM, Steve Levine
<steve.levine.1523 at gmail.com>wrote:

> Fellow users of GrADS,
>
> I am plotting gridded binary wind data in GrADS.  I can see the contour
> fields just fine, but I would like to interpolate the grid to find wind
> speed values at specific points - say a latitude and longitude pair.  If you
> are familiar with GEMPAK, I am looking for something similar to gdpoint that
> I could use in GrADS.  I have tried this with the gr2stn function, but to no
> avail.  Would it be possible to enter in a lat/lon pair, find its grid and
> simply pull the value from there?  If so, how?
>
> Thanks for your help!
>
> Steve Levine
> MS Student, Department of Marine & Environmental Systems
> Florida Institute of Technology
> 150 W University Blvd.
> Melbourne, FL 32901
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
>


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