[gradsusr] gr2stn doesn't work

[Ricardo Hallak]

Hi DjR, 

if nobody has answared you yet... 

After defining dx, dy and pg, try this: 

'set x 1' 
'set y 1' 
'd gr2stn(pg,20.4667,44.8167)' 

Hope this helps, 
Ricardo 

----- Mensagem original -----

> De: "Djordje Romanic" <djordje8 at gmail.com>
> Para: "GrADS Users Forum" <gradsusr at gradsusr.org>
> Enviadas: Domingo, 17 de Agosto de 2014 17:35:08
> Assunto: [gradsusr] gr2stn doesn't work

> Hello,

> I am calculating the pressure gradients (PGs) from the NCEP/NCAR
> reanalysis I MSLP data. The resolution of the data is 2.5 x 2.5
> degrees. I want to interpolate PGs to a particular coordinate that
> is not on the reanalysis grid. I was thinking to use gr2stn function
> for that but it does not work. This is my code:

> 'sdfopen 1948_1950.nc '

> 'define dx = 6.371e3 * cos(lat * 3.14159/180) * cdiff(lon *
> 3.14159/180, x)'
> 'define dy = 6.371e3 * cdiff(lat * 3.14159/180, y)'
> 'define pg = mag(cdiff(slp,x)/dx, cdiff(slp, y)/dy)'

> 'd gr2stn(pg,20.4667,44.8167)' *This coordinate is just an example

> This is the error message:

> Error from GR2STN: 2nd argument is not a station expression
> Operation Error: Error from gr2stn function
> Error ocurred at column 1
> DISPLAY error: Invalid expression
> Expression = gr2stn(pg,20.4667,44.8167)

> Please could you help me with this?

> Thanks,
> DjR

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