Output data from grib for given coordinates

[Goodson,Ron [Edm]]

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
Rodovia Presidente Dutra, km 39 - CEP 12630-000
Cachoeira Paulista, SP, Brasil
Telefone(CP): +55 12 3186 8502
Celular(SJC): +55 12 91678770 / +55 12 81528580
E-mail: guilherme.martins at cptec.inpe.br
E-mail alternativo: jgmsantos at gmail.com
Homepage: http://guilhermemartins.hd1.com.br/
-----------------------------------------------------------
Sent from Sao Jose Dos Campos, SP, Brazil 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20091209/804e4871/attachment.html