Comparison between ozone column depths and methane lifetimes computed by 1-D and 3-D models at different atmospheric O2 Levels
Authors/Creators
- 1. Pennsylvania State University
- 2. University of Leeds
- 3. Columbia University
Description
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.
Notes
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.
Funding provided by: Pennsylvania State University
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100008321
Award Number:
Funding provided by: Science and Technology Facilities Council of the United Kingdom*
Crossref Funder Registry ID:
Award Number: ST/T506230/1
Funding provided by: National Center for Atmospheric Research
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100005323
Award Number:
Funding provided by: NASA Planetary and Earth Science Divisions Internal Scientist Funding Model*
Crossref Funder Registry ID:
Award Number:
Files
Figure2eddy_1D.csv
Files
(1.4 MB)
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