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Ptop meaning for WRF

Khin Myat

Although I read the User guide manual carefully, I did not find the meaning of p-top. I just only found p-top requested value. Are these two "ptop and ptop_requested " same meaning?
When we set model vertical model level, there is table for choosing evert with the function of dstrectch/ptop. I could not understand how this table work. is there anybody can expalin me?
Any help is appreciated.
Thank you very much.

In the context of the information you provided, it seems like "ptop" and "ptop_requested" may have the same or related meanings. However, without more specific information about the context in which these terms are used, it is difficult to provide a definitive answer. It's possible that "ptop_requested" refers to a value that is being requested or specified, while "ptop" could refer to the actual value that is set or determined. ManageMyHealth

Regarding the table for choosing "evert" with the function of "dstrectch/ptop," it seems that you are referring to a specific feature or function within a model. Unfortunately, without further details or clarification, it's challenging to provide a precise explanation of how this table works. If you can provide more information about the specific model, its purpose, and the context in which this table is mentioned, I can try to assist you further.
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Hello Jeffreystarks,

Thank you very much for your reply and explanation.
Now I am trying to run simulation with previous typhoon case.
At first, I tried to simulate with the example namelist of huricane case that provided in user Manual for physics option. In that case , p_top requested value is 2000 and e_vert is 36. When I run with that value there was an error. When I search about the error in rsl.errror , it mentioned that e_vert value is lower, p_top requested is lower and change dstrectch value, dzbottom. So, I changed those value with recommended values in best user practice. Then it worked.
But I have not understood well how to choose the e_vert value and p-top requested value.
When I read the manual, the top row is dzstrectch/ptop is 50,30,20,10,1. How does these values come from? Which factor should be considered when we choose these value? What are the effect of these values in simulation?
Here I attached my namelist.wps and namelist.input. But I did not save the error of my previous run. So, I could not attached the error file of my previous run.
Thank you very much for your time and I am looking forward to your reply.


  • namelist.input
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  • namelist.wps
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Hi Khin,
p_top_requested should be based on the input data and how high up those data go in the atmosphere. It's typically best to keep p_top_requested at the default value of 5000, unless you have a known reason to modify it. Regarding choosing a good value for e_vert, take a look at this FAQ that discusses some information that may be useful.
Hi Kwerner,
Thank you very much for information and reply.
But, I am still confusing on choosing e-vertical. I read the discussion you mentioned and helped me understand more. The table describes minimum number of evert as a function of dzstretch/ptop only for dzbottom - 50 and dzmax - 1000m. if ptop and ptop_requested_value has same meaning, p-top_requested value 5000(Pa) but p-top in table is only 50. So, is there any unit difference between these two values. How do I choose evert? Or, do I misunderstand the table?
Another question is if I would like to change dzbottom and dzmax thickness , how do I choose evert?
I agree the table was a bit confusing. I am making a note to go back and add labels and units for clarification. In the meantime, the values along the left column are different options for dzstretch_s, and the values along the top are values for ptop, which is given in hPa. The unit for p_top_requested is in Pa, so if you have p_top_requested=5000 in your namelist, then you should be looking at the column with the heading of "50." You also have dzstretch_s = 1.1 in your namelist, so a reasonable number for e_vert would be 44.

Please help..
When I run the "mpirun -np 1 ./real.exe", I get this error..

I think both the inputlist and namelist is synced but not sure where I'm getting the error. My guess is that, e_vert is off somwhere.

Please help!!!!



  • namelist.input
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  • namelist.wps
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Hi vilic 4,
I think the error is there in no met_em file of domain 2 when real.exe is run. Please, check whether you link the met-em file for each domain in your run directory before you run real.exe.
I hope this may help you.

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Hi vilic 4,
I think the error is there in no met_em file of domain 2 when real.exe is run. Please, check whether you link the met-em file for each domain in your run directory before you run real.exe.
I hope this may help you.


I do have them.. so weird..

Hi Vilic,
According to your photo, I think your met_em file location is in your WPS directory. When you run real.exe, you need to link that met_em file in your WRF/ test/em_real run directory. The problem is you did not link the met_em file of domain 2 in your WRF directory.
Before you run real.exe, please do this step "
ln -sf ../../../WPS/met_em.d0*.2023-10* .
I also noticed that there is a difference of starting time and end time between your namelist.wps and namelist.input file. In namelist.wps , you set up the simulation time from 2023.10.15 00 hr to 12 hr. But in your namelist.input , you set up simulation hour 24 and starting and end time is 2023.10.15 00 hr to 2023.10.15 00 hr. Please, check your namelist carefully.

Best ,
Your inquiry is completely different than the original one on this thread. If you're still experiencing the issue, will you please post it as a new thread so that we can keep subjects separated? This helps with searching and reading posts in the future. Thanks!