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WRF-LES with MYJ-PBL

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n1o1o3n

New member
Hi,

I am trying to run a real case simulation with LES, using 1-way nesting from the coarser domain run with MYJ-PBL scheme. (but without ndown.exe)
For example, I set the domain, physics and dynamics as follows,

&domains
max_dom = 3
dx = 2500, 500, 100,

&physics
sf_sfclay_physics = 2, 2, 2
bl_pbl_physics = 2, 2, 0, (means MYJ - MYJ - LES)
isfflx = 1,

&dynamics
diff_opt = 1, 1, 2,
km_opt = 4, 4, 3,

I've already done the simulation and it seemed to be done without any errors.
And I checked the vertical wind speed profiles simulated by WRF-LES and normal WRF simulation with PBL scheme.
In normal real case simulation with PBL scheme, the vertical shear seemed to be appropriate. I was able to see the wind speed which was gradually getting weak as the ground approached.
In contrast, the wind shear simulated by the WRF(MYJ-MYJ-LES) with the configuration mentioned above didn't reproduce the attenuation of wind speed near surface. The wind speed near surface was almost the same as that of, for instance, 200m above the ground.
I think it imply fluxes and friction from the surface weren't taken into the account in the MYJ-MYJ-LES simulation, especially in the innermost LES domain.


Moreover, I've run similar simulations using YSU PBL scheme like,
YSU-YSU-YSU and YSU-YSU-LES.
In both simulation, I got good results in terms of wind speed, although bit strong vertical wind shear was found offshore.
So, seamless LES simulation with YSU PBL scheme is not a problem.


My question are,
1. whether I can run LES simulation using 1-way nesting from the coarser domain run with MYJ-PBL scheme without ndown.exe.
2. if possible, how I can solve the problem of the considerably weak vertical wind speed shear. (I guess it might be a problem of surface fluxes. isfflx??)

Thank you in advance.
 
Thank you for your quick response.

All the simulations were run on WRF v3.8.1.
I'm looking forward to your reply.

Best.
 
I believe that one should be able to run LES simulation using 1-way nesting with MYJ-PBL scheme without ndown.exe.

Please use the code I attach in this email to replace the previous one, then recompile WRF and run the case with the MYJ PBL scheme.

I hope this will fix the errors in your simulation. Please let me know whether it works.
 

Attachments

  • module_surface_driver.F
    338.1 KB · Views: 72
Thank you for your revised driver.

I was wondering what is the difference between MYJSFC(=2) and SFCLAY(=1) in terms of variables used in LES as surface fluxes.
And I didn't know that some of lines which are important for the LES simulation are commented out as default.

I will recompile and let you know the result soon.
 
Hi!!

I am happy to inform you a good news.
I replaced the driver file, recompiled and ran MYJ-LES again. It seems that the MYJ-LES simulation had been done successfully and I got the vertical wind speed profile similar to YSU-LES.

Thank you for your kind help.
 
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