Recently, Cooke et al. (2022) used a 3-D coupled chemistry-climate model (WACCM6) to calculate ozone column depths at varied atmospheric O₂ levels. They argued that previous 1-D photochemical model studies, e.g., Segura et al. (2003), may have overestimated the ozone column depth at low pO₂, and hence also overestimated the lifetime of methane. We have compared new simulations from an updated version of the Segura et al. model with those from WACCM6, together with some results from another 1-D and 3-D model. The discrepancy in ozone column depths is likely due to multiple interacting parameters, including lower boundary conditions, vertical and meridional transport rates, and different chemical mechanisms, especially the treatment of O₂ photolysis in the Schumann-Runge (SR) bands (175-205 nm). The discrepancy in tropospheric OH concentrations and methane lifetime between WACCM6 and the 1-D model at low pO₂ is reduced when absorption from CO₂ and H₂O in this wavelength region is included in WACCM6. Including scattering in the SR bands may further reduce this difference. Resolving these issues can be accomplished by developing an accurate parameterization for O₂ photolysis in the SR bands and then repeating these calculations in the various models. Work is already underway to this end.

We have data from three different models: 1-D photochemical model, WACCM6 3D model, and ROCKE-3D model. All models have been run with 4 different atmospheric O2 levels: 1 PAL, 0.1 PAL, 0.01 PAL, and 0.001 PAL. The source code for the 1-D photochemical model from Kasting group is available on Github: https://github.com/AoshuangJi/1-D-photochemical-model. The specific release for WACCM6 used in this paper is CESM2.1.3, which can be downloaded from the following: https://escomp.github.io/CESM/versions/cesm2.1/html/downloading_cesm. The source code for ROCKE-3D model is available through: https://simplex.giss.nasa.gov/gcm/ROCKE-3D/.

The data for generating Figure 1 are saved in Table 1 in our manuscript.

All the data from the 1D photochemical model are in Standard 1DnoCL.zip and seperate files with '1D' in the filename. Especially, the dataset 'Figure5_1D.csv' is from the 1D photochemical model by running one step from standard run with different solar zenith angles at the present atmosphere. The datasets 'Figure5_LBL.csv' is from Fernandez et al. (2007): https://doi.org/10.1016/j.jqsrt.2006.08.005. The data was recovered using webPlotDigitizer (https://automeris.io/WebPlotDigitizer/). We also use this tool for plotting the ozone column depths from Jaziri et al. (2022): https://doi.org/10.5194/cp-18-2421-2022.

All the data from the WACCM6 3D model are under WACCM6.zip.

All the data from the ROCKE 3D model are in a single file, named as 'ROCKE3D.nc'. 

The data can be downloaded and processed using MatLab. The MatLab code 'plotdata.m' to read data and plot all the figures is also uploaded here. The pathway to read data in the code should be adjusted to where readers save those data. More detailed information can be found in 'README.md'.

We have three different models. Files that contain '1D' in the file name are outputs from the 1-D photochemical model. The .zip file 'Standard1DnoCL.zip' includes outputs from Standard 1D model without chlorine at four different pO2 levels. To replicate those runs, one can adjust the chlorine Flag 'CLFLAG' in '/1DModelAoshuangJi/IO/input_atmchem.dat' to '1', and follow the instruction note on Github (see the link below). There are 'Converged' runs and 'ONESTEP' runs. All the important information can be found in files that contains 'outchem'. The data used for plotting are saved in /plot and have 'OUTPUT_PLOT' in the file name. 'NOS' indicates outputs from 1D runs without scattering, and 'NOSNOA' indicates without absorption by H2O/CO2. The sepearte 1D files '.csv' are specified for each figure.

All the ouputs from WACCM6 are saved in 'WACCM6.zip'. Seperate files like 'PI_j_mr_T_Z3_data_IC.csv' save most of the outputs for plotting from WACCM6. 'PI' means pre-industry, 'Ten' means 10% PAL pO2, 'One' means 1% PAL pO2, and 'Zero1' means 0.1% PAL pO2.

'ROCKED3D.nc' contains all the data from ROCKE-3D model.