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Modifying Landuse

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kwerner

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Modifying Landuse for a water-only domain

One way to do this is to edit phys/module_physics_init.F in the subroutine landuse_init. Try adding a line in this part of the code, just before the last line quoted here:

!Set arrays according to lu_index
itf = min0(ite,ide-1)
jtf = min0(jte,jde-1)
IF(usemonalb)CALL wrf_message('Climatological albedo is used instead of table values')
DO j = jts,jtf
DO i = its,itf
IS=nint(lu_index(i,j))

so that the new section reads:

!Set arrays according to lu_index
itf = min0(ite,ide-1)
jtf = min0(jte,jde-1)
IF(usemonalb)CALL wrf_message('Climatological albedo is used instead of table values')
DO j = jts,jtf
DO i = its,itf
lu_index = 16
IS=nint(lu_index(i,j))

Recompile the code after making this change (no need to do a 'clean -a' or to reconfigure since you are not changing anything in the Registry file). Check the field LU_INDEX in the wrfout file.



Modifying Landuse for a Specific Area within the Domain

There are a number of ways to do this. For e.g., if you want to change all desert categories to agriculture land, simply modify the LANDUSE.TBL and/or VEGPARM.TBL to change the physics properties from desert to the land category you would like to use. If you would like to only change the desert area in part of your domain, you may have to use read_wrf_nc.f and an NCL script that reads and writes data out after modification. To use read_wrf_nc.f, see the NCL section in the WRF User's Guide. This NCL presentation may also be useful.

If you modify input data to program REAL, use the namelist option surface_input_source=3 to avoid recalculation of dominant land categories (LU_INDEX).



Modifying Landuse Type Codes

As an example, look n dyn_em/module_initialize_real.F, around line 1627. Change the line beginning with grid%, from:

! Land use assignment
DO j = jts, MIN(jde-1,jte)
DO i = its, MIN(ide-1,ite)
grid%lu_index(i,j) = grid%ivgtyp(i,j)

to

grid%ivgtyp(i,j) = grid%lu_index(i,j)

Then recompile the code (no need to do a 'clean -a' or reconfigure, since you are not altering the Registry file). Check wrfinput_d01 after running real.exe. It should not have any effect on other fields in the input file.
 
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