vertical resolution

[kgeorge]

Hello,

Could anyone please help in how to estimate the vertical resolution in meters (based on e_vert levels)? is it possible in the wrf? i use the pressure cordinate system and is it possible to cut a plane at a height of 100m by setting an eta level at that exact 100m height?

I am kind of a new user so i am confused with the vertical resolution, any help is so appreciated
thank you

 

[Ming Chen]

wrfinput and wrfout files include the PH and PHB, the perturbation and base-state geopotential. You can derive the height of the vertical levels based on these two variables.

The vertical coordinate of WRF is hybrid terrain-following , and it is hard to set an eta level at exactly the 100m height.

 

[kgeorge]

Hello, I was trying to trying to put more values of eta layers between the first 1km but i have this cfl violation issue, can you please help me one more time ?

 

[Ming Chen]

CFL violation often indicates numerical instability. You can decrease time_step and turn on w_damping to overcome the CFL issue.

 

[kgeorge]

Dear ming chen,
thank you fr your reply, may i please know if it is ok if i use the timestep other than the 6 times dx , is it ok if it is lower than this? also, i had this violation of the cfl before and i turned off w_damping and then the simulation worked.. do you think it is normal?

 

[Ming Chen]

The maximum time step is 6 x delx. However, you can always use time step smaller than 6 x delx.

It is 'normal' the model runs successfully with w_dmaping on or off. This option suppresses strong vertical velocity and increases the model stability.