[Wrf-users] WRF namelist.input for nested domain - Times

[Eric Altshuler]

Dear Maria,

The "rule of thumb" to set time step in seconds = 6 * (grid spacing in km) is just a guideline. It does not guarantee stability of the model. Also, in your case 486 is not evenly divisible into 3600, so your output files will not have times exactly on the hour. Try using a time step that is smaller than 486 and also divisible into 3600 with no remainder (e.g. 450, 400, 360, 300). Try 450 first and if WRF still blows up, try 400, etc.

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: "Maria Prodanova" <Maria.Prodanova at meteo.bg>
To: Wrf-users at ucar.edu
Sent: Thursday, March 11, 2010 9:04:41 AM GMT -05:00 US/Canada Eastern
Subject: [Wrf-users] WRF namelist.input for nested domain - Times

Dear all,

I have experience with MM5, but I am a new user of WRF. I use WRF 3.1.1 
and I would like to run CMAQ 4.6 with output of WRF.
I run tutorial case without problem.  I prepare my domains - 3 nested 
domains (81, 27, 9 km). I run WPS without error.
I run real.exe and wrf.exe. I attach my namelist.input. The first I run 
real.exe and wrf.exe with the error in my namelist.input, I wrote  
time_step = 60 instead of 486, in this run I used fdda. All was OK, but 
the calculation was very slowly. I wrote  the write value of  time_step 
= 486, but the wrf.exe was  killed. I took out fdda options. As I think 
now all finished successfully ( I attach rsl.error.0000).
But in the files wrfout_d0*  the times is not correct ( my  
history_interval = 60,  60,   60). The times are:
Times =
  "2010-01-11_00:00:00",
  "2010-01-11_01:04:48",
  "2010-01-11_02:01:30",
  "2010-01-11_03:06:18",
  "2010-01-11_04:03:00",
  "......................................,
  "2010-01-13_11:07:48",
  "2010-01-13_12:04:30" ;
You may see the header of the wrfout_d01 and Times in the attached file 
z_Times_1_n.

When I wrote  time_step = 60 all was OK:
2010-01-11_00:00:00",
  "2010-01-11_01:00:00",
  "2010-01-11_02:00:00",
  "2010-01-11_03:00:00",
  "2010-01-11_04:00:00",
  "......................................,
  "2010-01-13_11:00:00",
  "2010-01-13_12:04:00" ;

I expected to be the same because history_interval = 60,  60,   60, and 
it is important for CMAQ the output to be every hrs.

Where is my error? Any information regarding this subject is greatly 
appreciated.

Thank you.

Maria


-- 
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Maria Prodanova-Boiadjieva
National Institute of Meteorology and Hydrology
66 Tzarigradsko shaussee, Sofia 1784, Bulgaria
Phone: (+3592) 462 4598
Fax: (+3592) 988 03 80, 988 44 94
e-mail:Maria.Prodanova at meteo.bg
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