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LU_INDEX changed in wrfout file

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New member
Hello, WRF team
I am using wps/3.9.1 and wrf/ for a simulation using
  • geog_data_res='default','default','default' in the namelist.wps file.
  • input_from_file=.true.,.true.,.true., in the namelist.input file.

The problem is that I found the LU_INDEX from the wrfout file is different from the LU_INDEX in the geo_em.d0*.nc file.
I have tested for both single urban land class (LU_INDEX ranged between 1 and 17 in my case) and multiple land class (LOW_DENSITY_RESIDENTIAL, HIGH_DENSITY_RESIDENTIAL, COMMERCIAL_INDUSTRIAL) (LU_INDEX ranged between 1 and 33) in the geo_em.d0*.nc file.
However, after the WRF ran, the LU_INDEX values in the wrfout files from both single and multiple urban classes are changed to between 1 and 18.

Would you please let me know if it is normal to have LU_INDEX changed in the wrfout files?
And why does the single and multiple urban class returned the same LU_INDEX in the wrfout file?
Is there any way to avoid such a problem?


LU_INDEX is adjusted in REAL to make sure it is consistent with soil and landsea mask. However, such adjustment is minor and I don't think there should have large changes.
Thanks, Ming
I noticed that the results did not change much from the validation result.
For multiple urban land classes, the LU_INDEX of 31, 32 and 33 have all been changed back to 13 in the wrfout file.
Does that mean I have done anything wrong from my settings for multiple urban classes?

No you didn't do anything wrong. This is the adjustment made in REAL, which is done to make urban landuse type to be consistent with the urban type in input data (MODIS).
Dear WRF users,
I have observed the same "problem" with WRF version 4.0. After ingesting new urban land use-land cover data via the WPS, the urban landscape (now lu_index = 31,32, and 33) was modified in the WRF output files to lu_index=13. All the met_em*nc files are correct, the problem is in the WRF output files. My question is, what values of the LU_INDEX variable is using WRF during the simulation ?