How can I output the cloud optical thickness when selecting RRTMG?

[hliu20]

Hello,
I am using WRF4.2 to simulate the radiative effects of SOA, and I have enabled the indirect radiative effect. I noticed that setting icloud=1 requires ra_sw_physics=1,4 and ra_lw_physics=1,4. Therefore, I chose the RRTMG scheme for both SW and LW. However, with this setup, I am unable to output Cloud Optical Thickness (TAUCLDI and TAUCLDC). （https://forum.mmm.ucar.edu/threads/...output-taucldi-and-taucldc-is-always-0.9381/）
My questions are:
1. If I choose ra_sw_physics=3 and ra_lw_physics=3, and the output includes COT, does this mean that the 'cloud effect on the optical depth in radiation' is enabled during the simulation?
2. If the answer to question 1 is no, and I choose RRTMG, how can I output/calculate the 'Cloud Optical Thickness for Ice' and 'Cloud Optical Thickness for Water'?

 

[Ming Chen]

Please see my answers below:

Hello,
I am using WRF4.2 to simulate the radiative effects of SOA, and I have enabled the indirect radiative effect. I noticed that setting icloud=1 requires ra_sw_physics=1,4 and ra_lw_physics=1,4. Therefore, I chose the RRTMG scheme for both SW and LW. However, with this setup, I am unable to output Cloud Optical Thickness (TAUCLDI and TAUCLDC). （https://forum.mmm.ucar.edu/threads/...output-taucldi-and-taucldc-is-always-0.9381/）
My questions are:
1. If I choose ra_sw_physics=3 and ra_lw_physics=3, and the output includes COT, does this mean that the 'cloud effect on the optical depth in radiation' is enabled during the simulation?

Yes this is correct.

2. If the answer to question 1 is no, and I choose RRTMG, how can I output/calculate the 'Cloud Optical Thickness for Ice' and 'Cloud Optical Thickness for Water'?

Please look at the variables 'tauc' and 'taucmcl' in RRTMG scheme, they represent In-cloud optical depth in RRTMG. More details can be found in the paper below:
Iacono, M. J., J. S. Delamere, E. J. Mlawer, M. W. Shephard, S. A. Clough, and W. D. Collins, 2008: Radiative forcing by long–lived greenhouse gases: Calculations with the AER radiative transfer models. J. Geophys. Res., 113, D13103. doi:10.1029/2008JD009944

 

[hliu20]

Thank you for your reply!
For question 1, I still have some doubts. If I set ra_LW_physics=4 (LW: rrtmg) but ra_SW_physics=2 (SW: goddard), does the simulation default to enabling the 'cloud effect on the optical depth in radiation'?
Moreover, how about ra_lw_physics=5 but ra_sw_physics=5 ?

 

[Ming Chen]

I believe that cloud effect is considered in Goddard radiation scheme, although the variable name of In-cloud optical depth might be different to that in RRTMG.