Comparison between ozone column depths and methane lifetimes computed by 1-D and 3-D models at different atmospheric O2 Levels

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..., 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 atmospher..., 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' indic...近期，Cooke等人（2022）采用三维化学-气候耦合模式（WACCM6），针对不同大气氧气分压条件下的臭氧柱总量展开计算。他们提出，此前诸如Segura等人（2003）所开展的一维光化学模式（1-D photochemical model）研究，或许高估了低氧气分压下的臭氧柱总量，进而也高估了甲烷的大气寿命。 我们将更新版Segura等人模式的最新模拟结果，与WACCM6的模拟结果，以及另外一款一维模式和三维模式的相关结果进行了对比。二者在臭氧柱总量上的差异，可能源于多个相互作用的参数，包括下边界条件、垂直与经向输送速率，以及不同的化学机制，尤其是对舒曼-朗格（Schumann-Runge, SR）波段（175~205 nm）内氧气光解过程的处理方式。当考虑该波长区间内二氧化碳与水蒸气的吸收作用时，WACCM6与一维模式在低氧气分压下的对流层羟基（OH）浓度以及甲烷寿命方面的差异有所缩小…… 本次研究共采用三款不同模式的数据：一维光化学模式、WACCM6三维模式，以及ROCKE-3D模式。所有模式均设置了4种不同的大气氧气分压水平：1倍当前大气水平（Present Atmospheric Level, PAL）、0.1 PAL、0.01 PAL以及0.001 PAL。卡斯廷（Kasting）课题组研发的一维光化学模式的源代码可在GitHub获取：https://github.com/AoshuangJi/1-D-photochemical-model。本研究使用的WACCM6特定版本为CESM2.1.3，可通过以下链接下载：https://escomp.github.io/CESM/versions/cesm2.1/html/downloading_cesm。ROCKE-3D模式的源代码可通过以下途径获取：https://simplex.giss.nasa.gov/gcm/ROCKE-3D/。 用于绘制图1的数据已收录于本文稿件的表1中。所有一维光化学模式的数据集均存储于Standard1DnoCL.zip压缩包，以及文件名包含‘1D’的独立文件中。其中，数据集‘Figure5_1D.csv’来自一维光化学模式，该模式以当前大气条件下的标准运行结果为初始，通过改变太阳天顶角进行了单步运行……相关数据可使用MatLab进行下载与处理。用于读取数据并绘制所有图表的MatLab代码‘plotdata.m’也已同步上传，用户需根据自身存放数据的路径调整代码中的数据读取路径。更多详细信息可参阅‘README.md’文件。 本次研究共采用三款不同模式。文件名包含‘1D’的文件均为一维光化学模式的输出结果。压缩包‘Standard1DnoCL.zip’包含了无氯条件下标准一维模式在4种不同氧气分压水平下的输出结果。若要复现此类运行，用户可将路径‘/1DModelAoshuangJi/IO/input_atmchem.dat’中的氯标记‘CLFLAG’调整为‘1’，并按照GitHub上的说明文档进行操作（详见下方链接）。本研究包含‘收敛运行（Converged）’与‘单步运行（ONESTEP）’两类结果。所有关键信息均可在文件名包含‘outchem’的文件中找到。用于绘图的数据存储于/plot目录下，且文件名包含‘OUTPUT_PLOT’。‘NOS’代表无散射条件下一维模式运行的输出结果，‘NOSNOA’则代表……