Output data from grib for given coordinates

[Nathan Cool]

Thanks everyone.

I was able to do this by manually entering in each command, but I need to
run this in batch mode, if possible.

A simple script I have now is:

'open nww3.ctl'
'set lon 206'
'set lat 33'
'set t 3'
'd HTSGWsfc'

Grads is then executed using the following arguments:

    gradsc -lbxc point.gs

...where point.gs is the script above.

In batch mode, I don't see the result output. Is there a way to run this in
batch mode, or perhaps a GRADS command to output the result into a file?

-Nathan


On Wed, Dec 9, 2009 at 8:49 AM, Goodson,Ron [Edm] <Ron.Goodson at ec.gc.ca>wrote:

>  I'm lazier than that...
>
> I just set lat lon to be the coordinates I want, then print out the result
> of displaying the data.
>
> This is only useful if you don't mind getting the nearest grid point to
> your lat/lon.  Otherwise - simply use the GrADS "bilinear".
>
> Hmmm .. thought that was in the script library but don't see it .. so here
> is a copy I have buried in one of my scripts.  Haven't used this script in
> many years, so no warrantly expressed or implied.  You will probably have to
> modify it as it looks like it was hardwired for a specific-sized grid.  And
> it looks like it would run pretty slow.
>
>
>
> -------------------------------------------------------------------------------------------
>
> *****bilinear interpolation from 4 nearest gridpoints:
> function bilinear(llat, llon, myvar)
> **_llat = subwrd(myposition, 1)
> **_llon = subwrd(myposition, 2)
> ************say 'q w2gr 'llon' 'llat
> 'q w2gr 'llon' 'llat
> *************say result
> xdim=subwrd(result,3)
> xdim=0.+xdim
> if ( xdim <= 1.) ; xdim=96.+xdim ; endif
> ydim=subwrd(result,6)
> * nearest x dimensions :
> x1= math_int(xdim)
> x2 = x1 + 1
> * the weights are
> xw1= xdim-x1
> xw2= 1.-xw1
> * nearest y dimensions :
> y1= math_int(ydim)
> y2 = y1 + 1
> * the weights are
> yw1= ydim-y1
> yw2= 1.-yw1
> 'set x ' x1
> 'set y ' y1
> 'd ' myvar
> line2 = sublin(result,2)
> pointa = subwrd(line2,4)
> 'set x ' x2
> 'set y ' y1
> 'd ' myvar
> line2 = sublin(result,2)
> pointb = subwrd(line2,4)
> 'set x ' x1
> 'set y ' y2
> 'd ' myvar
> line2 = sublin(result,2)
> pointc = subwrd(line2,4)
> 'set x ' x2
> 'set y ' y2
> 'd ' myvar
> line2 = sublin(result,2)
> pointd = subwrd(line2,4)
> newtemp = pointa*xw2*yw2 + pointb*xw1*yw2 + pointc*xw2*yw1 + pointd*xw1*yw1
> return newtemp
> * station = f(x1,y1)*xw2*yw2+
> * f(x2,y1)*xw1*yw2+
> * f(x1,y2)*xw2*yw1+
> * f(x2,y2)*xw1*yw1
>
>
>  ------------------------------
> *From:* GRADSUSR at LIST.CINECA.IT [mailto:GRADSUSR at LIST.CINECA.IT] *On
> Behalf Of *Guilherme Martins
> *Sent:* December 9, 2009 8:49 AM
> *To:* GRADSUSR at LIST.CINECA.IT
> *Subject:* Re: Output data from grib for given coordinates
>
> Hi Nathan!
>
> You can use the lats4d.gs. You can extract levels, variables, specific
> times and coordinates. The output format can be, .nc, .bin, .grb.
>
> Guilherme.
>
> 2009/12/9 Nathan Cool <nathan at nathancool.com>
>
>> Good morning everyone,
>>
>> I'm working on a project where I need to extract data from a grib file for
>> specific coordinates only. Is there a way, using GRADS, where I can specify
>> a given coordinate (lon, lat), and retrieve data just for that coordinate
>> for each time series in a grib file? Or is GRADS not the tool to do this; I
>> was thinking of just dumping the grib using wgrib and text parsing it, but
>> thought GRADS might have an easier way.
>>
>> Thanks in advance,
>>
>> -Nathan
>>
>
>
>
> --
> -----------------------------------------------------------
> José Guilherme Martins dos Santos
> Grupo de Modelagem da Atmosfera e Interfaces - GMAI
> Divisão de Modelagem e Desenvolvimento - DMD
> Centro de Previsão de Tempo e Estudos Climáticos - INPE
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> -----------------------------------------------------------
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>
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