Cloud fraction values 0/1 when using icloud=1

[Rui_Silva]

Dear all,

I am using WRF model coupled with chemistry to study aerosol effects. When looking at the CLDFRC variable at different levels, the fields only show values that are either 0 or 1. This is very strange, because I have selected the namelist.input option icloud=1 (based on Xu and Randall 1996) which should give continuous cloud fraction values (i.e., between 0 and 1), not binary fields. This happens during all the simulation period.
.
Here are my &physics options:

&physics
mp_physics = 10, 10, 10,
ra_lw_physics = 4, 4, 4,
ra_sw_physics = 4, 4, 4,
radt = 36, 36, 36,
slope_rad = 1, 1, 1,
topo_shading = 1, 1, 1,
swint_opt = 1,
sf_sfclay_physics = 1, 1, 1,
sf_surface_physics = 2, 2, 2,
bl_pbl_physics = 5, 5, 5,
bldt = 0, 0, 0,
cu_physics = 5, 5, 0,
cugd_avedx = 1,
cudt = 0, 0, 0,
do_radar_ref = 1,
isfflx = 1,
ifsnow = 0,
surface_input_source = 1,
num_soil_layers = 4,
sf_urban_physics = 0,
seaice_threshold = 0.0,
fractional_seaice = 1,
sst_update = 1,
num_land_cat = 33,
icloud = 1,
cu_rad_feedback = .true., .true., .false.,
cu_diag = 1, 1, 0,
progn = 1, 1, 1,
/


Is this normal?

Thank you.

Kind regards,
Rui Silva

 

[Ming Chen]

Are you running wrf-chem?

 

[Rui_Silva]

Are you running wrf-chem?

Yes! Version 4.1.3.

Kind regards,
Rui Silva

 

[Ming Chen]

Rui,
I have run a quick test using WRF-ARW, and icloud = 1 option gives me fractional cloud cover, which is what we expected.
I am not sure why wrf-chem behaves differently. We don't provide support for wrf-chem because NOAA is responsible for it. Although they no longer provide user support, people in the community are still active to exchange information in the Forum. Hope someone can provide helpful information regarding your issue.

 

[Rui_Silva]

Dear Ming,

I also did a quick test using WRF without chemistry. It seems that the problem is related with the chemistry. I will check what's happening.

Thank you.

Kind regards,
Rui Silva

 

[Ming Chen]

Rui,
Thank you for the update. Please post your solution here if you solve the problem, so that other users who have the same issue can benefit from your work. Thanks in advance.