Spectral nudging of ONE variable in outermost domain

[koszutam]

I am trying to run a simulation of an atmospheric river off the western US coast with two domains with horizontal resolution of 9 km and 3 km. I want to apply spectral nudging to the outermost domain and only nudge the "uv" variables. How do I switch off/not initiate nudging for "t" and "q". Would removing these options from the namelist do what I want or are they required? Thanks for any insight you can provide!

 

[Ming Chen]

You can set

grid_fdda = 2, 0, 0, 0

This will enable spectral nudging only in the outermost domain.

There are options to control which levels and what variables are nudged. For example,

 if_zfac_q  (max_dom)                = 0,       ! 0= nudge q in all layers, 1= limit nudging to levels above k_zfac_q
  k_zfac_q  (max_dom)                = 0,       ! 0= model level below which nudging is switched off for q

Please find detailed information in "WRF/run/README.namelist"

 

[wrfyangliu]

Hi Ming,
I have a question. From user's Guide, I found that if_zfac_q (max_dom) and k_zfac_q (max_dom) are for grid nuding ？Does it also suitable for spectral nuding?
For grid nudging, nudging u and v, temp, qvapor in the PBL. For spectral nudging, nudging u and v, temp, geopotential height in the PBL. Can grid nuding and spectral nudging be used together？ I want to nudge u and v, temp, qvapor, geopotential height in the PBL, is it possiable?