NARR data analysis

[Krishna Santhanam]

Hi Eric,
It works.  Thanks for the technical description, some how the
"rc=write(temp.dat,variables2)" command doesn't work but
"write(temp.dat,variables2) produces values.
Thanks again,
Krishna

On Mon, Jul 6, 2009 at 7:43 PM, Eric Altshuler <ela at cola.iges.org> wrote:

> Hello Krishna,
>
> When you are displaying data that is preprojected (i.e. the grads
> descriptor file includes a PDEF specification), any 'display' command will
> produce the following message in the command window:
>
> Notice:  Automatic Grid Interpolation Taking Place
>
> In a script, when you display a variable, the script variable 'result'
> captures the messages that grads would have sent to the command window. When
> the data is preprojected, the message about grid interpolation appears
> first. So you might have the following response to the command 'd ugrd30m':
>
> Notice:  Automatic Grid Interpolation Taking Place
> Result value = 5.26342
>
> To retrieve the numerical value, you need to change the following line in
> your script:
>
> dum1=sublin(result,1)
>
> to the following:
>
> dum1=sublin(result,2)
>
> Note that this is not necessary when using non-preprojected data (i.e. the
> ctl file does not have a PDEF specification), because the message about grid
> interpolation won't be generated.
>
> You should also use the following syntax for the write function:
>
> rc=write(temp_30m.dat,variables2)
>
> instead of:
>
> write(temp_30m.dat,variables2)
>
> Although the latter syntax will write to the file successfully, it will
> also cause an error message "Unknown command: 0". The former syntax is the
> correct one to use.
>
> Best regards,
>
> Eric L. Altshuler
> Assistant Research Scientist
> Center for Ocean-Land-Atmosphere Studies
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705-3106
> USA
>
> E-mail: ela at cola.iges.org
> Phone: (301) 902-1257
> Fax: (301) 595-9793
>
> ----- Original Message -----
> From: "Krishna Santhanam" <ksanthanam at PRECISIONWIND.COM>
> To: GRADSUSR at LIST.CINECA.IT
> Sent: Sunday, July 5, 2009 3:09:30 PM GMT -05:00 US/Canada Eastern
> Subject: NARR data analysis
>
> Hi all,
> I am trying to write u and v wind component from NARR data into a file. The
> text file that is written is having no value but "interpolation" . Could
> anyone help me how to solve this issue.
> By the way here is the grads script that i used
> ____________________
>
> function main()
> 'open narr-a_221_20010101_0000_000.ctl'
>  cntt=1
>  say "cntt ="cntt
>  cntx=290
>  while(cntx<=350)
>  cnty=60
>  while(cnty<=100)
>  count=1
>  count1=count+7
>  while(count<=count1)
> 'set t 'count
> 'set x 'cntx
> 'set y 'cnty
> 'set z 1'
> 'd ugrd30m.'cntt
>  dum1=sublin(result,1)
>  x13=subwrd(dum1,4)
> 'd vgrd30m.'cntt
>  dum1=sublin(result,1)
>  x23=subwrd(dum1,4)
>  variables2=x13'   'x23
>  write(temp_30m.dat,variables2)
>  count=count+1
>  endwhile
>  cnty=cnty+1
>  endwhile
>  cntx=cntx+1
>  endwhile
> ---------------------------------------
>
> Thanks,
> Krishna
>



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