[gradsusr] setting time with intervals

Tue Jan 15 19:40:23 EST 2013

Yes, GRIB is the one data format that makes this very easy. Just remember that you must re-reun gribmap whenever you edit your TDEF entry. You might consider keeping more than one descriptor file handy, one with the full-res time axis, and others with various sampling rates, each will have its own unique index file.
--Jennifer

On Jan 15, 2013, at 7:31 PM, Sagar P Parajuli wrote:

> Thank you Jeff,
> Since I can specify the interval in tdef, I can do whatever I want. 
> 
> Thank you,
> 
> Sagar
> 
> On Tue, Jan 15, 2013 at 2:19 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
> Since you are using GRIB formatted data, this is very easy to do.  The question remains what time interval you want.  In your initial email you said you wanted data only at 12 PM.  However, in subsequent emails, you said you wanted to use an interval of 2.  Given a time interval of 6 hrs in your data, those time increments do not match.  It's easy to make changes based on what you want, though.
> 
> Anyway, everything you need to do involves changing the TDEF line of your control file:
> 
> tdef 1460 linear 00Z01jan2009 6hr
> 
> This controls the time interval of the data you will see.  That last entry is the interval.  Change it to 12hr or 24hr/1dy depending on what time interval you want.  Also you'll want to change the second entry, 1460, which is the number of time slices you want to view.  You'll either divide that by 2 or 4 depending on your time interval.  Finally, if you use a 24 hour interval, make sure to change the initial time string (currently 00Z01JAN2009) to the correct UTC hour.  Let me know if you need clarification or any further examples.  You can find documentation on this at http://www.iges.org/grads/gadoc/descriptorfile.html#TDEF.
> 
> Jeff
> 
> 
> On Tue, Jan 15, 2013 at 2:05 PM, Sagar Parajuli <psagar at utexas.edu> wrote:
> Hi Jeff,
> 
> Attached is my ctl file.
> 
>  
> 
> Sincerely,
> 
>  
> 
> Sagar Prasad Parajuli
> 
> Graduate Student/Research Assistant
> 
> University of Texas at Austin
> 
> Jackson School of Geosciences
> 
> 1 University Station C1100, JGB 5.322
> Austin, TX 78712
> 
> Contact: psagar at utexas.edu
> 
> Cell: 512 965 4093
> 
> 
> 
>  
> 
> From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Jeff Duda
> Sent: Tuesday, January 15, 2013 1:06 PM
> To: GrADS Users Forum
> Subject: Re: [gradsusr] setting time with intervals
> 
>  
> 
> Sagar,
> What does your control file look like?  Can you send it to me please?
> 
> Jeff
> 
> On Tue, Jan 15, 2013 at 12:23 PM, Sagar P Parajuli <psagar at utexas.edu> wrote:
> 
> Hi Jeff
> I need to plot and print those extracted data. I know how to print it but I want to know how to specify the time interval required. The code I am using is:
> open ERA.INTERIM.SFC.ctl
> set lat 31.4
> set lon 61.3
> set t 1 last (It will print values pertaining to all t but I want to specify an interval of 2).
> set gxout print
> set prnopts %g 1 1
> d mag(no10usfc,no10vsfc)
> 
> How can I specify the required time interval for t?
> 
> thank you,
> 
> -Sagar
> 
> 
> 
> 
> On Tue, Jan 15, 2013 at 10:03 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:
> 
> What do you want to do with the data?  Do you want to make plots in Grads or just extract the data?  If it's the latter, then you don't really even need to use Grads.
> 
> Jeff
> 
>  
> 
> On Tue, Jan 15, 2013 at 8:47 AM, Sagar P Parajuli <psagar at utexas.edu> wrote:
> 
> Hi Jeff,
> I think I didn't clarify my question. I am writing control file for extracting some wind speed data corresponding to particular time of a day. What I could do in grads is:
>  set t 1 last 
> But I want to do this skipping certain values eg. I want values corresponding to t = 1, 3, 5, 7, 9, etc (i.e. with certain interval). So, I need to skip some data and only extract those datas.
> How can I do this?
> 
> 
> Thank you so much again.
> 
> 
> 
> Sagar
> 
> 
> 
> 
> On Mon, Jan 14, 2013 at 11:13 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
> 
> Time interval is specified in the control file used to open the data file.  However, if you used xdfopen or sdfopen, there may be a different way to determine the time interval.  In those cases, you should be able to find it by dumping the contents.  If your data are in netCDF format, for example, you could use ncdump -h (data file) to find out.
> 
>  
> 
> Jeff Duda
> 
> On Mon, Jan 14, 2013 at 9:47 PM, Sagar P Parajuli <psagar at utexas.edu> wrote:
> 
> Hi all,
> I need to extract wind speed data at a particular time (12:00 pm only) everyday from the 6 hourly data of one year. So I need to set time as,
> t = 1, 1460, 2 (start, end, interval). How is the time interval specified in grads? 
> 
> Thank you very much for your help. 
> 
> 
>  
> 
> Sagar P. Parajuli
> 
> Graduate Research Assistant
> 
> The University of Texas at Austin
> Jackson School of Geosciences
> e-mail: psagar at utexas.edu
> 
> Contact: +1 512 965 4093
> 
> _______________________________________________
> gradsusr mailing list
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> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
>  
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> --
> 
> Best regards,
> 
>  
> 
> Sagar P. Parajuli
> 
> Graduate Research Assistant
> 
> The University of Texas at Austin
> Jackson School of Geosciences
> e-mail: psagar at utexas.edu
> 
> Contact: +1 512 965 4093
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> --
> 
> Best regards,
> 
> Sagar P. Parajuli
> 
> Graduate Research Assistant
> 
> The University of Texas at Austin
> Jackson School of Geosciences
> e-mail: psagar at utexas.edu
> 
> Contact: +1 512 965 4093
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> 
> 
> 
> 
> -- 
> 
> Best regards,
> 
> 
> Sagar P. Parajuli
> 
> Graduate Research Assistant
> 
> The University of Texas at Austin
> Jackson School of Geosciences
> e-mail: psagar at utexas.edu
> 
> Contact: +1 512 965 4093 _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org

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