two way nest

Discuss the nesting capability within the model itself and any problems you might have run into.

two way nest

Postby aiguozhe5 » Sun Apr 11, 2010 2:15 am

when i run the two way nest with the two input , the rsl.error.0000 file showde me as follow:
what dose this mean?

d02 2005-08-28_08:08:00 2 points exceeded cfl=2 in domain d02 at time 2005-08-28_08:08:00 hours
d02 2005-08-28_08:08:00 MAX AT i,j,k: 78 22 21 vert_cfl,w,d(eta)= 2.090222 35.18721 3.1394452E-02

thinks a lot
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Re: two way nest

Postby dbh409 » Tue Jun 29, 2010 2:45 pm

This means that the model is generating NaN values. This most often occurs when the time step is too large. What do you have the horizontal resolution and time step set to?
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Re: two way nest

Postby aiguozhe5 » Sun Sep 12, 2010 4:23 am

dx 15000 , 5000
time step 60
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Re: two way nest

Postby jimmyc » Mon Sep 13, 2010 3:09 am

You could try a 30 second time step.

The error you are seeing violates the CFL criterion at 2 grid points. Sometimes this indicates the numerical solution is unstable and will eventually cause the model to blow up (crash), but sometimes this happens at a few points and eventually settles down. Ideally, you don't want to see CFL errors since there is noise generated in the model that can have rather unrealistic effects. If it is short lived, you can call it noise, but if it is pervasive then you will want to understand what is causing it.
The views expressed in this message do not necessarily reflect those of NOAA or the National Weather Service or the University of Oklahoma.
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