[gradsusr] reading ds094.0 data with template

[Eric Altshuler]

Antoine, 


I'm not sure if you can template this dataset "as is" in grads. Each daily file contains 4 forecasts initialized every 6 hours, and each forecast runs out to 9 hours. So there is a 3-hr overlap between consecutive forecasts. Some time levels will have data from two different forecasts. Your ctl file, as it stands, can't account for the overlapping forecasts. It may be possible to handle this situation using the ensemble dimension, treating each 9-hr forecast as a separate ensemble member, but it may be tricky (different data formats have different templating requirements). See the following link: 


http://grads.iges.org/grads/gadoc/ensembles.html 


You may also have to re-organize your data by using wgrib2 to extract the data for each 9-hr forecast from the daily files, and write each forecast into its own individual file. This will make it easier to handle the staggered initial times. 


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: "Antoine Molin" <amolin at plenr.fr> 
To: gradsusr at gradsusr.org 
Sent: Tuesday, November 13, 2012 6:17:37 AM 
Subject: [gradsusr] reading ds094.0 data with template 




Hi, 



Using ds094.0 daily files like : « cdas1.20121001.pgrbh.grb2 », each data at time 00h is -9.99E+08. 

It is not a problem if i want to read one day file : if the first data at 00h is false, it can be obtained as last data of the day before. 

But if i want to read one month with daily files (see enclosed files) using template, all my data at t=00h are false ; See the U_wind data at lat 45, lon 5, t=1 to 744 in grads_IEE.txt. 



i think that perhaps my .ctl is not good ? I tried undef= -9.99 e+08 and undef=9.999E+20, but it doesn’t change anything. 



In fact we have 2 data for time 00h in these files, and the false one is read. 



So I think i am not using « template » as it should ! Is there a change to do in my .ctl ?? 



Thanks, and best regards. 





Antoine Molin 

Etudes de vent PlenR 

Tel : 03 20 47 99 76 


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