Data to support: Anthropogenic influence on tropospheric reactive bromine since the pre-industrial: Implications for ice-core bromine trends

Tropospheric reactive bromine (Bry) influences the oxidation capacity of the atmosphere by acting as a sink for ozone and nitrogen oxides. Aerosol acidity plays a crucial role in Bry abundances through acid-catalyzed debromination from sea-salt-aerosol, the largest global source. Bromine concentrations in a Russian Arctic ice-core, Akademii Nauk, show a 3.5-fold increase from pre-industrial (PI) to the 1970s (peak acidity, PA), and decreased by half to 1999 (present day, PD). Ice-core acidity mirrors this trend, showing robust correlation with bromine, especially after 1940 (r=0.9). Model simulations considering anthropogenic emission changes alone show that atmospheric acidity is the main driver of Bry changes, consistent with the observed relationship between acidity and bromine. The influence of atmospheric acidity and Bry should be considered in interpretation of ice-core bromine trends., We use a global 3D chemical transport model GEOS-Chem (version 11-02d, https://github.com/geoschem/geos-chem/tree/v11-02d-prelim) for historical simulations. The model is driven by MERRA-2 assimilated meteorological fields from the Goddard Earth Observing System (GEOS) (Gelaro et al., 2017), and contains detailed HOx-NOx-VOC-ozone-halogen-aerosol tropospheric chemistry (Wang et al., 2021) and fully coupled stratospheric chemistry (Eastham et al., 2014). Details of the modeled bromine chemistry are shown in Fig. S1‒S3.  Sea-salt-aerosol debromination occurs in both open ocean (Jaeglé et al., 2011) and blowing snow (Huang & Jaeglé, 2017) sourced sea-salt-aerosol. Following Zhai et al. (2023), ozone dry deposition velocity onto snow and ice is updated to 0.01 cm s−1, consistent with observations (Simpson et al., 2007). Snowpack bromine emissions (Swanson et al., 2022; Zhai et al., 2023) are not included in the model.
Model simulations are performed under three anthropogenic emission sc..., , # Data to support: Anthropogenic Influence on Tropospheric Reactive Bromine since the Pre-industrial: Implications for Ice-core Bromine Trends

This data set contains modeling output to support the Article \"Anthropogenic Influence on Tropospheric Reactive Bromine since the Pre-industrial: Implications for Ice-core Bromine Trends\".

### Description of the data and file structure

The dataset contains results from the 3 GEOS-Chem model simulations: PI (pre-industrial), PA (peak acidity) and PD (present day). Please refer to the article for detailed description of the simulation setup. Each model simulation contains 28 data files (all model outputs are monthly averaged values):

1.    PIconc.2007MMDD.nc: concentration files, 1 file for every 3 months, 4 files in total for PI

2.    PAconc.2007MMDD.nc: concentration files, 1 file for every 3 months, 4 files in total for PA

3.    PDconc.2007MMDD.nc: concentration files, 1 file for every 3 months, 4 files in total for PD

4.    BrBudget.xl...