Change Default Minimum Reflectivity from -35 to 0 dBZ

MattW

New member
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

Moderator
Staff member
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

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

Ming Chen

Moderator
Staff member
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.
 
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