[Wrf-users] cfl error in very complex topography

[Ólafur Rögnvaldsson]

Dear Jorge.

In our experience you may need to set "epssm" to an even greater number than what David suggests.

The value we use for our SARWeather system is:

epssm = 0.3, 0.6, 1.2,

where the model resolution is 9, 3, and 1km, respectively.

This setup, using the following 41 full-sigma levels 

    eta_levels = 1.000, 0.993, 0.985, 0.969, 0.953, 0.937, 0.921, 0.905,
                 0.888, 0.870, 0.853, 0.835, 0.816, 0.798, 0.778, 0.759,
                 0.739, 0.718, 0.696, 0.674, 0.651, 0.628, 0.603, 0.577,
                 0.550, 0.522, 0.492, 0.461, 0.426, 0.389, 0.348, 0.302,
                 0.242, 0.212, 0.182, 0.152, 0.121, 0.091, 0.061, 0.030,
                 0.000,

gives a stable solution over a 24 hour period for a 160x160 points 1km domain (nested from 9 and 3 km domains) centered over Mt. Aconcagua:

https://www.sarweather.com/forecast/result/20130614-214823-09d847906bb8/static/wind/0

Hope this is of some use and good luck with your simulations.

Best, Ólafur.

Ps. You need to register (https://www.sarweather.com/accounts/register/  -> this is free of charge) if you want to download the wrfout-files from the simulation I linked to.

> Jorge,
> 
> I see you have tried many of the recommended steps.  Have you tried
> setting epssm to a larger number?  For my 4th domain, 0.2 is
> sufficient 
> epssm       = 0.1, 0.1, 0.1, 0.2,
> but you might want as much as 0.4 or even higher.  Change that in the
> &dynamics section of your namelist.input file, rerun real.exe, and try
> your run again.
> 
> David
> -- 
> David Ovens		 e-mail: ovens at atmos.washington.edu
> Research Meteorologist    phone: (206) 685-8108
> Dept of Atm. Sciences      plan: Real-time MM5 forecasting for the
> Box 351640                        Pacific Northwest
> University of Washington          http://www.atmos.washington.edu/mm5rt
> Seattle, WA  98195               Weather Graphics and Loops
>                                  http://www.atmos.washington.edu/~ovens/loops
> 
> 
> On Fri, Jun 14, 2013 at 01:36:11PM -0400, Jorge Alejandro Arevalo Borquez wrote:
>> Dears,
>> 
>> I am trying to run WRF over Central Chile. I am using 4 nested domains, the
>> finner one has 1 km of horizontal resolution with 50 vertical levels.
>> Domains includes Aconcagua mountain wich is about 6900 masl.
>> 
>> When I run wrf I get cfl errors at few seconds after start in grid-points
>> near to Aconcagua, but wrf crash in the call to radiation parametrization.
>> 
>> I tried to decrease time-step, use adaptive time-step, edit GEOGRID.TBL  to
>> use 1-2-1 smooth option, change my set of parametrization. Even I tried to
>> edit geog data and apply a simple filter to smooth topography near
>> aconcagua region. All efforts has concluded with the same cfl errors.
>> 
>> Any advice is welcome
>> 
>> Regards
>> 
>> 
>> 
>> Atentamente
>> Jorge Ar?valo B?rquez
>> Profesor Auxiliar
>> Coordinador LMA-UV
>> Departamento de Meteorolog?a
>> Universidad de Valpara?so
>> 56-32-2508710
> 
>> _______________________________________________
>> Wrf-users mailing list
>> Wrf-users at ucar.edu
>> http://mailman.ucar.edu/mailman/listinfo/wrf-users
> 
> 
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Kveðja/regards,
Dr. Ólafur Rögnvaldsson
Belgingur, reiknistofa í veðurfræði
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