Developing the chemistry module for 27 fluorinated greenhouse gases (F-gases): Reactions, emissions, and implementation in GEOS-Chem

Fluorinated greenhouse gases (F-gases) are widely used in refrigeration, air-conditioning, semiconductor, and other industries, contributing a total direct radiative forcing only surpassed by carbon dioxide and methane. Current modeling efforts of F-gases use simplified chemical schemes and ignore three-dimensional dynamics, which limits the quantification of their chemical impacts, and a full suite of F-gases is not currently included in atmospheric chemical transport models. Here, we develop and implement a chemistry module in the GEOS-Chem model with 27 additional F-gases (including minor CFCs, minor HCFCs, HFCs, PFCs, SF₆, NF₃, and SO₂F₂) with constrained emissions. The updated simulations capture most of the surface mole fraction baseline trends and some pollution events for F-gases in 2020–2021, with a normalized mean bias between −14 % and 5 % at the Mace Head station and −17 % and 3 % at the ShangDianZi station. The impact of emission spatial distributions decreases with lifetime, suggesting that accurate global modeling of the background of long-lived species (>10 years) is less dependent on the spatial distribution of the emission than on the total magnitude. The impact of the updated simulation on key reactive species, including ozone, HO_x, ClO_x, and NO_x, is <1 %. For species with 10-year lifetimes, F-gas chemical losses drive 20–40 % changes in their mixing ratios. Our work provides a comprehensive F-gases chemistry module complementing the major CFCs and HCFCs in the GEOS-Chem model, and this suite of F-gases provides potential applications for understanding their climate impacts and atmospheric processes.