How to decide the number of vertical (or Eta) levels (e_vert) in namelist.input?

[sadya_islam20]

Hi,

I am running WRF with both ERA5 Reanalysis data(pressure level analysis and surface analysis- https://rda.ucar.edu/datasets/ds633.0/index.html#!access) and NCEP North American Regional Reanalysis (NARR) (https://rda.ucar.edu/datasets/ds608.0/). I used e_vert =38 for both dataset and there was no problem in running real.exe and wrf.exe. But I don't know whether I am doing it right or not.
So, my question is how can I decide which level to use for e_vert?

 

[Ming Chen]

Hi,
e_vert can be specified based on your case. It usually should be larger than 40 with p_top = 50 hPa. If your model top goes higher, for example p_top = 1hPa, you will need to increase e_vert to 61 or more. There is no specific rules how to determine the number of e_vert. It all depends on the case.

 

[sadya_islam20]

Thanks for your reply. I saw that the recommended value is 5000 Pa and I am using 10000 Pa. Would you mind explaining little bit how to decide on this p_top and what it does actually? Making the model top higher (1 hPa) or lower (100 hPa) - what does it mean and how it might affect simulation results?

 

[kwerner]

Take a look at this FAQ for a bit of additional information on determining the appropriate number of vertical levels.

 

[sadya_islam20]

Take a look at this FAQ for a bit of additional information on determining the appropriate number of vertical levels.

Thanks!!