[RegCNET] Nan error during model run-Common problem

Fri Jan 29 13:35:44 CET 2010

Dear Ashraf and Abdou,
Thanks for your mail and suggestions.
After several experiment I just tried to replace the ICBC file.
I also learnt the issue of map scale factor from Moet.
I checked the value of 'xmap' in between NORMER and ROTMER as suggested by Moet.
I am getting better value with ROTMER.
Now it's working fine for me.
Thanks all.

Regards
Satyaban

On Fri, 29 Jan 2010 17:09:19 +0530  wrote
>Hi,

  If you are using LAMCON projection, check the values of 'xmap' in 
your (DOMAIN.CTL) . The value of this factor should be less than 
1.1. Sometimes this factor is a source of NaN as well.

Ashraf

Satyaban Bishoyi Ratna wrote:
>
> Dear Sara and All,
> Thanks for your mail and detail information about the Nan error in the 
> RegCM3 model run.
> As this Nan error is a common problem in RegCM, I have some point in 
> continuation with this discussion.
> Mainly, even though model is encountering Nan error during the 
> integration still it proceeds up to completion of the integration. For 
> long simulation people don't monitor continuously whether model 
> running smoothly or there is a chance of nan error.
> Sometimes, people see that they have completed their simulation 
> successfully but at the time of analyse their model output they 
> realize that there is Nan error and the model output is no use.
> So they need to start or restart the simulation again.
> In my opinion it will better if there will be facility such that, In 
> case there is a Nan error during the run it should come out 
> immediately and stop the integration automatically without proceed 
> further.
> In this way we can save lot of time.
>
> Thanking you.
>
> Best regards
> Satyaban
>
> On Thu, 28 Jan 2010 22:24:41 +0530 wrote
> >Dear Dwijenra,
>
> This is the most common question on the list (in fact, it was answered
> the other day). Everyone, please read the user's guide! It contains
> valuable information that will help you run your simulations.
> http://users.ictp.it/RegCNET/regcm.pdf
>
> The model is sensitive to the time step used. The first rule of thumb is
> to use 3 times the horizontal grid spacing. In your case, 60 km, so 180
> is the best to start with. However, in cases of steep topography you may
> need to decrease this time step. You might want to try 150, for example.
>
> If you are doing a long simulation, and this just happens once or twice,
> you can work around this. Set the time step to a lower value, restart
> the model to a point before where it blew up, and then after this point,
> stop the model, put the time step back to its original value, and
> restart the model. So for example, if my model had died on January 5th,
> I would probably restart at the beginning of January, do that month at a
> lower time step, and then continue the simulation in February at the
> original time step if that's been working. Note that this is acceptable
> to do once or twice in a long simulation (like > 5 years), but if it
> happens more often, you should restart the simulation from the beginning
> at a shorter time step.
>
> In the regcm user guide, there is a table that gives suggestions (these
> are just suggestions) for time steps for different grid spacing (Table
> 12, page 40):
> Table 12: Time steps with different resolutions:
>
> dx(km) dt(sec) abatm(sec) abemh(hr) radfrq(min)
> 10 30 90 18 30
> 20 60 120 18 30
> 30 100 300 18 30
> 45 150 300 18 30
> 50 150 450 18 30
> 60 200 600 18 30
> 90 225 900 18 30
>
> There is discussion of how to set the time step on page 35 in the user's
> guide.
> cheers
> sara
>
>
> d d wrote:
> > Dear RegCNET Users,
> >
> > I am having similar problem as Dr. Satyaban getting the NaN error
> > while running RegCM for 6 months simulation. The ICBC files are OK
> > when i checked them on grads. The Model can run successfully upto 4
> > months and after that it encounters NaN error for last two months.
> > I had tried to restart the simulation but still the same
> > domain.param configuration
> > Idate1=1997010100 start day of simulation
> > Idate2=1997063000 End day of simulation
> > ds = 60km
> >
> > regcm.in configuration
> > Idate0=1997010100
> > Idate1=1997010100
> > Idate2=1997063000
> > dt=180
> > radfrq=30
> > abemh=18
> > abatm=540
> >
> > please kindly suggests whar might be the problem
> >
> > Best regards
> > Dwijendra
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > RegCNET mailing list
> > RegCNET at lists.ictp.it
> > https://lists.ictp.it/mailman/listinfo/regcnet
>
>
> -- 
> Sara A. Rauscher
> T-3 Fluid Dynamics
> MS B216
> Los Alamos National Lab
> Los Alamos, NM 87545 USA
> (505) 606-0512
>
> _______________________________________________
> RegCNET mailing list
> RegCNET at lists.ictp.it
> https://lists.ictp.it/mailman/listinfo/regcnet
>
>
> -------------------------------------------------------------------------------
> Dr. Satyaban Bishoyi Ratna
> Computational Atmospheric Sciences Team
> Scientific & Engineering Computing Group
> Centre for Development of Advanced Computing (C-DAC)
> Pune University Campus, Ganeshkhind
> Pune - 411 007, Maharashtra, India
> E-mail: satyabanb at cdac.in
> Tel (O): +91-020-2570 4226, (Cell): +91-094223 56326
> --------------------------------------------------------------------------------
>  
>
>
> ------------------------------------------------------------------------
>
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-------------------------------------------------------------------------------
Dr. Satyaban Bishoyi Ratna
Computational Atmospheric Sciences Team
Scientific & Engineering Computing Group
Centre for Development of Advanced Computing (C-DAC)
Pune University Campus, Ganeshkhind
Pune - 411 007, Maharashtra, India
E-mail: satyabanb at cdac.in
Tel (O): +91-020-2570 4226,  (Cell): +91-094223 56326
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