Inquiry Regarding Appropriate chem_opt Selection for CBMZ–MOSAIC with Aqueous Chemistry

[Setareh Rahimi]

Dear WRF-Chem users,

I hope this message finds you well.

I am currently working with WRF-Chem (v4.6.1) to study the interactions between aerosols and clouds. My intention is to use the CBMZ gas-phase chemistry in combination with the MOSAIC aerosol module.

However, I have noticed that there are several available options for chem_opt that include CBMZ with MOSAIC, some of which also include aqueous-phase chemistry (e.g., options 7, 8, 9, 10, 31–34, etc.). While the User’s Guide notes that these configurations differ in their treatment of aqueous reactions, it is not entirely clear what the specific differences are among these options.

Could you please clarify:

1. What are the key distinctions among the chem_opt options that pair CBMZ with MOSAIC and include aqueous chemistry?

2. Which configuration would be most appropriate for simulating aerosol–cloud interactions, particularly when aqueous-phase processes are of interest?

Any additional documentation or guidance regarding the scientific or numerical differences among these chem_opt settings would be greatly appreciated.

Thank you very much for your time and assistance.

Kind regards,

[Mary Barth]

Setareh,

There may be more information in the literature about what exact chem_opt was used for previous studies. I was involved in two studies that used CBMZ-MOSAIC 4-bin with aqueous chemistry, but I don't have the namelist.input files to say exactly which one was used. I would guess chem_opt=32. However, it could have been chem_opt=9. It looks like the difference between those two is that 32 includes DMS and 9 does not. DMS is primarily emitted from the ocean. So consider that in your choice. 

I am pretty sure that the chem_options that include aqueous chemistry all use the same routine: module_cmu_bulkaqchem.F

That routine uses the Fahey and Pandis aqueous phase mechanism which focuses on sulfur chemistry. 

Again, review the literature. A key point is to evaluate the role of aerosol-cloud interactions, you need to change the aerosol or their precursor emissions. In other words, you use the same chem_option for sensitivity simulations to ensure the code is making calculations via the same modules. 

Good luck,

Mary

p.s. Now that we have the MOZART-MOSAIC chemistry option, I am more familiar with that configuration. The MOZART chemistry suite is what we give support for on this email group.

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Mary Barth 

Senior Scientist   

phone: 303-497-8186    email: bar...@ucar.edu

NSF - National Center for Atmospheric Research

P.O. Box 3000

Boulder, CO 80307

Staff web page

SIMA Web Site

MUSICA Web Site

DC3 Web Site 

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