Possible error: Units of effective radius of droplet and ice in cloud

[wbr2023]

Hi, I am using the CESM 2.1.3.

Today, while searching for variables related to the effective radius of ice and droplets in cloud, I found two variables 'rel_cloud' and 'rei_cloud' in cloud_diagnostics.F90. Are the units of these two variables incorrect? Should they be in micron; Also, I would like to know if these two variables are only for stratiform cloud.



Sincerely hope to get your advice.
Best wishes!

 

[brianpm]

Yes, I believe this is a typo, and the units of both REL and REI should be microns.

I do want to note that I think that rei_cloud and rel_cloud both seem to be only used with the old 1-moment microphysics. If you are running with CAM5 or CAM6, these fields should not get used.

There is REI and REL in the pbuf data structure, and that might be the field that you want to be looking at. Here you can see REI gets added to the pbuf from different places depending on what scheme is handling the microphysics:

$grep -r -n "pbuf_add_field.*REI" .
./cam7/micro_pumas_cam.F90:645:   call pbuf_add_field('REI',        'physpkg',dtype_r8,(/pcols,pver/), rei_idx)
./spcam/crm_physics.F90:175:  call pbuf_add_field('REI',         'physpkg', dtype_r8, (/pcols,pver/),                                rei_idx)
./cam/micro_pumas_cam.F90:599:   call pbuf_add_field('REI',        'physpkg',dtype_r8,(/pcols,pver/), rei_idx)
./cam/rk_stratiform.F90:177:   call pbuf_add_field('REI',       'physpkg', dtype_r8, (/pcols,pver/), rei_idx)

If you're using CESM 2.1.3 you'll probably see "mg" instead of "pumas" (and no "cam7").