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Radiation scheme at high resolution over complex terrain

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P

peter_

Member
Hi:
I would like to mention a problem I found over time in high resolution simulations over very complex terrain also from other people (see e.g. forum.mmm.ucar.edu/phpBB3/viewtopic.php?f=43&t=8729). In my case WRF4.2 runs with some CFL warnings but stops always when it comes to the first radiation call. From my point of view the problem is not related to numerical instability or missing memory or disk space or insuficient processors or bad forcing data. My run is successful with 2 domains but fails at the first radiation call when including the third domain. I am attaching namelist.input, namelist.wps and one of the rsl files. Any suggestion on the solution for this radiation problem with high resolution over complex terrain ?
 

Attachments

  • namelist.input
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  • namelist.wps
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  • rsl.error.dat.dat
    9.6 MB · Views: 24
Hi Peter,

Would you please rerun this case with the following options:

Code: 
w_damping = 1
epssm = 0.2, 0.2, 0.9

Let me know whether this case can at least run more time steps without CFL violation.

By the way, I notice that you set a very high model top (1 hPa). What data did you use to drive this case? Thanks.
 
Hi:
Thank you for your reply. I will try your suggestion but w_damping = 1 is not a final option for me as I want to study gravity waves. I forgot to mention that the domain resolutions are respectively 9, 3 and 1 km and the forcing data is rda.ucar.edu/datasets/ds083.3. CFL and vert_CFL warnings appear at the lowest levels.
 
Please try the option w_damping =1 and increase epssm value. We need to make sure the case can be run first. then we can turn off w_damping and see whether the case can still run.
I knew that the resolution is 9-3-1km, which is shown in your namelist.input. I am actually concerned of thee model top, which is pretty high. GFS data also reach up to 1 hpa, so I suppose the data would be fine.
 
Dear Ming Chen:
Thank you very much. As you guessed, cfl disappeared and the run survived the first radiation call at 30 minutes. Should I now turn off w-damping and see what happens ?
 
That is good to know.
Now let's set w_damping =0 and rerun this case. Please keep me updated about the results. Thanks.
 
Dear Ming Chen:
WRF is running. As you guessed, it was not a radiation but a numerical instability issue. Thank you so much. Should I leave epssm at the current values ? Should I try a lower value for d03 or is the present value physically acceptable ?
 
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