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lowest levels in metgrid are below the surface

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peter_

Member
Hi:
I am doing a simulation over complex and sharp terrain with WPS and WRF 4.2 and FNL ds083.3 forcing data (isobaric levels). The run crashed at startup so I went back to the preprocessing and discovered that at least in some regions levels 2 to 8 (over 34) are below level 1 (ground) in the met_em files. However, I did not detect anything suspicious in wrfinput. I was told to use only 4 pt interpolators in METGRID.TBL to avoid the crossing of the lowest levels but it did not work for me. So my questions are: Can real.exe overcome the problem of having 7 or less levels below the surface in some regions ? Or can I somehow fix the crossing of levels ? What tests should I perform on wrfinput to ensure its integrity ? I would very much appreciate your suggestions.
 
Hi,
It is not unusual that some metgrid levels are blow the ground. Thy shouldn't cause problems because REAL program will handle this issue later.
What is the error message in your WRF run? Please send me your namelist.wps and namelist.input to take a look.
 
Hi:
Thank you for the reply. I am surprised that I am having 7 levels below the ground in some zones and I wonder if I can do some tests on wrfinput to find out if anything is wrong in the initial conditions. My run usually fails wihin the first time step in the SFCLAY or LW module (it depends on some parameter changes in namelist.input). I am including below namelist.wps and namelist.input

View attachment namelist.wpsView attachment namelist.input
 
Peter,

I looked at the website https://rda.ucar.edu/datasets/ds083.3/, which provides the FNL data you use to run the case.
This FNL data has 26 mandatory (and other pressure) levels from 1000 millibars to 10 millibars. But in your namelist.input, you set

p_top_requested = 100,
num_metgrid_levels = 34,

These settings are apparently not consistent with the FNL. I suppose REAL should fail. However, It seems that you can run real.exe successfully but wrf.exe failed to run. Is this the case?
 
Hi:
Please notice that the information is not completely updated in the RDA Description section. Click below where it says "more details" and you will find the 34 levels for temperature, velocity and humidity. In Pa they are 100000 , 97500 , 95000 , 92500 , 90000 , 85000 , 80000 , 75000 , 70000 , 65000 , 60000 , 55000 , 50000 , 45000 , 40000 , 35000 , 30000 , 25000 , 20000 , 15000 , 10000 , 7000 , 5000 , 4000 , 3000 , 2000 , 1500 , 1000 ,
700 , 500 , 300 , 200 , 100 and the ground level. So this explains why I am successful with real.exe. I understand that real may be ignoring all isobaric level information below the surface at every grid point, but what tests should I then perform on wrfinput to ensure that no problems have been transferred to the initial conditions ?
 
You can check wrfinput_d01, looking at all upper level data. But I won't expect anything wrong in REAL. This is because we have done many cases with levels below ground in met_em files.
Would you please tell what is the error message in your rsl files when you run wrf.exe? Probably that can give us some hints.
 
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