Change Default Minimum Reflectivity from -35 to 0 dBZ

[MattW]

Is there a way to change the default minimum reflectivity output by WRF in clear-air regions from -35 dBZ to 0 dBZ? I'm using DART to assimilate radar reflectivity into WRF, and the large number of -35 dBZ values is making the reflectivity data assimilation difficult. I'm using the Thompson microphysics scheme in WRF 3.9.1.1, and I noticed there appears to be a spot in the code for that which sets a minimum value for reflectivity, but I was wondering if there might be a namelist option to set it somewhere since I'd prefer not to have to modify and recompile the microphysics code.

Thanks,

Matt

 

[Ming Chen]

You can find the following line i various codes (phys/module_mp_thompson.F, phys/module_mp_gsfcgce.F, phys/module_mp_morr_two_moment.F, phys/module_mp_lin.F, etc.):

refl_10cm(i,k,j) = MAX(-35., dBZ(k))

Your an change it to

refl_10cm(i,k,j) = MAX(0., dBZ(k))

Unfortunately there is no namelist option to limit the minimum value of radar reflectivity.

 

[MattW]

Thanks! Would I need to recompile all of WRF after making this change, or just the module that I changed?

 

[Ming Chen]

Matt,
You don't need to recompile everything. Juts go to top WRF directory, then type the command: ./compile em_real
In this way, only the code you changed will be recompiled.