Introduce in-line photolysis rate calculations from TUV-x

[mattldawson]

What is the feature/what would you like to discuss?

This enhancement would use TUV-x to calculate photolysis rates.

Science motivation: CESM currently uses a look-up table for photolysis rates that was pre-calculated for different ozone and cloud conditions. Aerosol changes have not been considered in the look-up tables. However, it has been shown that photolysis rates can be strongly changed by increases in aerosols in both the stratosphere (for example after volcanic eruptions) or in the troposphere with strong pollution events. TUV-x is an inline model that calculates photolysis rates and takes into account both changes from ozone and aerosols (not clouds currently). The inclusion of this model is expected to significantly improve the representation of photolysis rates in the model, with implications for, e.g., OH and ozone in polluted regions, and is also important for geoengineering studies that use stratospheric aerosols.

Is there anyone in particular you want to be part of this conversation?

@dkinnison @stacywalters @tilmes @fvitt @lizziel

Will this change (regression test) answers?

No

Will you be implementing this enhancement yourself?

Yes

[lizziel]

Please include me in this discussion as well. I am a member of the GEOS-Chem Support Team and am currently developing Cloud-J to interface to other models, the first one being GEOS-Chem.

GEOS-Chem is in the pipeline to be included in CAM (see #484). A future version of GEOS-Chem will require Cloud-J so I will need to integrate that into CESM as well. The plan is that Cloud-J will eventually become part of MUSICA. Seeing how TUV-x is integrated into the model will help guide me on how to submit Cloud-J.

[mattldawson]

Hi @lizziel - sure thing! I just submitted a draft PR #784 for this if you're interested to take a look.