black carbon optical properties files for CAM6

[Shen Han]

Dear all,
I am currently utilizing CESM2.1.3 CAM6 with RRTMG to model the climatic effects of black carbon. In the MAM4 module, the default optical properties input file for black carbon is 'bcpho_rrtmg_c100508.nc', which is set by the "mode_defs" namelist, as shown in the figure below. I am reaching out with a couple of queries related to this:

1. I've noticed that the optical properties file for BC in both the accum mode and primary carbon mode is the same, i.e., 'bcpho_rrtmg_c100508.nc'. Could you help me understand the rationale behind using the same file for these two modes?
2. I am curious about the derivation of certain variable values within the aforementioned .nc file, specifically parameters like 'abs_lw', 'scat_lw', 'asym_lw', 'abs_nir', 'ssa_nir' and 'refindex' ,and so on. While I'm informed that the 'refindex' is based on Bond (2006), I would like to gain insights into the methodologies or sources used to determine the other parameters. Additionally, if I'm looking to adjust these values, are there any specific precautions or guidelines I should be aware of?

I am genuinely thankful for any assistance you can provide, as it will be instrumental in furthering my research. Your expertise and guidance are invaluable to me, and I appreciate the time you take to address my questions. Below is my version_info.txt.

Thanks; any insight would be much appreciated.

 

[peverley]

Moving your question to the CAM-Chem forum in the hopes that they can answer!

 

[Xingru Wu]

Have you found ways to adjust these values？ I have a similar need.