RELHUM calculation in SCAM

[bidyut]

Hi All,
I am running SCAM (Gettleman et al. 2019) for IOP cases.
My question is: how is relative humidity (RELHUM) calculated? Is it with respect to ice or water?
Thanks.

 

[cacraig]

Looking at src/physics/cam/cam_diagnostics.F90 where the outfld call for RELHUM is made, there is a line:

ftem(:ncol,:) = state%q(:ncol,:,ixq)/ftem(:ncol,:)*100._r8

Looking higher up in the code, ixq is retrieved via the line:

call cnst_get_ind('Q', ixq)

'Q' is water vapor. If the call to "cnst_get_ind" had 'CLDICE', then that would would have been retrieving the ice.

The RELHUM calculation is using 'Q'.

 

[bidyut]

Thank you @cacraig for the detailed answer.
Regards.