BAT-VBS model in GEOS-Chem

[msulprizio]

Your name

Melissa Sulprizio

Your affiliation

Harvard

Provide a clear and concise overview of the new feature requested.

Camilo Serrano Damha (McGill) writes:

The Binary Activity Thermodynamics (BAT) model is an efficient, reduced-complexity activity coefficient model which enables accounting for the nonideal mixing behavior in aqueous organic solutions as a function of water content (or, indirectly, relative humidity). The BAT model is coupled with the existing equilibrium volatility basis set (VBS) gas–particle partitioning framework of GEOS-Chem. The inputs required to use the BAT-VBS model in GEOS-Chem include the oxygen-to-carbon ratios, molar masses, pure-component saturation mass concentrations of organic compounds, and atmospheric relative humidity. For needed inputs not already in GEOS-Chem, estimation methods were implemented to determine those in an objective manner for running the BAT-VBS model in GEOS-Chem. One of the attractive features of determining OA equilibrium partitioning with the BAT-VBS method is its thermodynamically sound and efficient framework for computing the water uptake and related feedback on the OA mass concentrations of organic compounds. The OA water uptake predicted by the BAT-VBS model is due only to organic compounds, without the influence of inorganic species. The BAT-VBS model captures variations in effective saturation mass concentrations of organic species with relative humidity, a feature that other VBS methods lack. In addition, the BAT-VBS model can predict the extent of liquid–liquid phase separation occurring within aqueous organic mixtures.

Reference(s)

• Serrano Damha et al. (in prep)

Papers describing the BAT-VBS model:

• Gorkowski, K., Preston, T. C., & Zuend, A., Relative-humidity-dependent organic aerosol thermodynamics via an efficient reduced-complexity model. Atmospheric Chemistry and Physics, 19(21), 13383–13407, https://doi.org/10.5194/acp-19-13383-2019, 2019.
• Serrano Damha, C., Cummings, B. E., Schervish, M., Shiraiwa, M., Waring, M. S., and Zuend, A.: Capturing the relative-humidity-sensitive gas–particle partitioning of organic aerosols in a 2D volatility basis set, Geophys. Res. Lett., 51, e2023GL106095, https://doi.org/10.1029/2023GL106095, 2024.

Will you be implementing this feature yourself?

No

Additional information

No response

[yantosca]

We would need a user from the community to "champion" for this feature to be included in a future version.