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Observed TCO is derived from the Multi Sensor Reanalysis version 2 (MSR2) dataset (van der A et al., 2010). Fourteen total ozone satellite retrieval datasets from the instruments TOMS (on the satellites Nimbus-7 and Earth Probe), SBUV (Nimbus-7, NOAA-9, NOAA-11, and NOAA-16), GOME (ERS-2), SCIAMACHY (Envisat), OMI (EOS-Aura), and GOME-2 (Metop-A) were used in MSR2. Ozone profiles are obtained from the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH, version 2.5), dataset for the period 1984−2014 (Davis et al., 2016) and version 4.2x Aura Microwave Limb Sounder (MLS) Level 2 data for the period of 2005−14 (Livesey et al., 2016). The SWOOSH dataset is a merged record of stratospheric ozone and water vapor measurements taken by several limb sounding and solar occultation satellites (SAGE-II/III, UARS HALOE, UARS MLS, and Aura MLS instruments). It has 31 pressure levels from 300 to 1 hPa. The TP region is defined as 27.5°−37.5°N, 75°−105°E. A summary of the models and data available used in this study is provided in Table 1. In this study, the zonal anomaly of one variable is defined as the departure of this variable at a given location from its corresponding zonal mean.
Model Resolution Stratospheric Chemistry Ozone Datasets BCC-CSM2-MR 320 × 160 longitude/latitude;
46 levels; top level 1.46 hPaPrescribed (CMIP6 dataset) Historical
SSP2-4.5
SSP5-8.5Wu et al. (2020)
Xin et al. (2019)BCC-ESM1 128 × 64 longitude/latitude;
26 levels; top level 2.19 hPaPrescribed (CMIP6 dataset) Historical Zhang et al. (2018b) CESM2 288 × 192 longitude/latitude;
32 levels; top level 2.25 hPaPrescribed (other) Historical
SSP2-4.5
SSP5-8.5Danabasoglu (2019a)
Danabasoglu (2019b)CESM2-WACCM 144 × 96 longitude/latitude;
70 levels; top level 4.5 × 10−6 hPaInteractive chemistry Historical
SSP2-4.5
SSP5-8.5Danabasoglu (2019c)
Danabasoglu (2019d)CNRM-CM6-1 T127; Gaussian Reduced with 24572 grid points in total distributed over 128 latitude circles (with 256 grid points per latitude circle between 30°N and 30°S reducing to 20 grid points per latitude circle at 88.9°N and 88.9°S); 91 levels; top level 78.4 km Simplified online scheme Historical
SSP2-4.5
SSP5-8.5Voldoire (2018)
Voldoire (2019)CNRM-ESM2-1 T127; Gaussian Reduced with 24572 grid points in total distributed over 128 latitude circles (with 256 grid points per latitude circle between 30°N and 30°S reducing to 20 grid points per latitude circle at 88.9°N and 88.9°S); 91 levels; top level 78.4 km Interactive chemistry Historical
SSP2-4.5
SSP5-8.5Seferian (2018)
Seferian (2019)E3SM-1-0 Cubed sphere spectral-element grid; 5400 elements with p=3; 1° average grid spacing; 90 × 90 × 6 longitude/latitude/cubeface;
72 levels; top level 0.1 hPaSimplified online scheme Historical Bader et al. (2019) FGOALS-g3 180 × 80 longitude/latitude;
26 levels; top level 2.19 hPaPrescribed (CMIP6 dataset) Historical
SSP2-4.5
SSP5-8.5Li (2019) GFDL-CM4 360 × 180 longitude/latitude;
33 levels; top level 1 hPaPrescribed (CMIP6 dataset) Historical
SSP2-4.5
SSP5-8.5Guo et al. (2018a)
Guo et al. (2018b)GFDL-ESM4 360 × 180 longitude/latitude;
49 levels; top level 1 PaInteractive chemistry Historical
SSP2-4.5
SSP5-8.5Krasting et al. (2018)
John et al. (2018)IPSL-CM6A-LR 144 × 143 longitude/latitude;
79 levels; top level 80 kmPrescribed (CMIP6 dataset) Historical
SSP2-4.5
SSP5-8.5Boucher et al. (2018)
Boucher et al. (2019)MRI-ESM2-0 192 × 96 longitude/latitude;
80 levels; top level 0.01 hPaInteractive chemistry Historical
SSP2-4.5
SSP5-8.5Yukimoto et al. (2019a)
Yukimoto et al. (2019b)SAM0-UNICON 288 × 192 longitude/latitude;
30 levels; top level ~2 hPaPrescribed (CMIP6 dataset) Historical Park and Shin (2019) UKESM1-0-LL 192 × 144 longitude/latitude;
85 levels; top level 85 kmInteractive chemistry Historical
SSP2-4.5
SSP5-8.5Tang et al. (2019)
Good et al. (2019)Table 1. Overview of models and data available used in this study.
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In this study, we evaluated TCO and stratospheric ozone mixing ratios over the TP derived from 14 models that participated in CMIP6: BCC-CSM2-MR, BCC-ESM1, CESM2, CESM2-WACCM, CNRM-CM6-1, CNRM-ESM2-1, E3SM-1-0, FGOALS-g3, GFDL-CM4, GFDL-ESM4, IPSL-CM6A-LR, MRI-ESM2-0, SAM0-UNICON, and UKESM1-0-LL. Five of these models (CESM2-WACCM, CNRM-ESM2-1, GFDL-ESM4, MRI-ESM2-0, and UKESM1-0-LL) use fully coupled, interactive stratospheric chemistry, while two (CNRM-CM6-1 and E3SM-1-0) use a simple chemistry scheme. The remaining seven (BCC-CSM2-MR, BCC-ESM1, CESM2, FGOALS-g3, GFDL-CM4, IPSL-CM6A-LR, and SAM0-UNICON) do not include an interactive chemistry scheme and instead prescribe stratospheric ozone according to the CMIP6 ozone database (except in the case of CESM2, which prescribes ozone values from CESM2-WACCM simulations) (Keeble et al., 2020).
To evaluate long-term changes in stratospheric ozone over the TP, this study uses two types of simulations, the CMIP6 historical simulations and the Scenario MIP future simulations (O’Neill et al., 2017). The CMIP6 historical simulations run from 1850−2014, and the models are forced by common datasets based on observations that include historical changes in short-lived species and long-lived greenhouse gases (GHGs), global land use, solar forcing, and stratospheric aerosols from volcanic eruptions. This study only uses the historical simulation for the period of 1984−2014 for a comparison with the SWOOSH observations. The Scenario MIP future simulations run from 2015−2100 and follow the newly developed shared socioeconomic pathways (SSPs), which provide future emissions and land-use changes based on scenarios directly relevant to societal concerns regarding climate change impacts, adaptation, and mitigation. This study explores future ozone changes under the middle of the road (SSP2) and fossil-fueled development (SSP5) scenarios. Specifically, we use the ozone output derived from the SSP2-4.5 and SSP5-8.5 scenarios. It should be noted that the SSP2-4.5 and SSP5-8.5 simulations from BCC-ESM1, E3SM-1-0 and SAM0-UNICON are not available publicly at the time this paper was prepared.
Model | Resolution | Stratospheric Chemistry | Ozone | Datasets |
BCC-CSM2-MR | 320 × 160 longitude/latitude; 46 levels; top level 1.46 hPa | Prescribed (CMIP6 dataset) | Historical SSP2-4.5 SSP5-8.5 | Wu et al. (2020) Xin et al. (2019) |
BCC-ESM1 | 128 × 64 longitude/latitude; 26 levels; top level 2.19 hPa | Prescribed (CMIP6 dataset) | Historical | Zhang et al. (2018b) |
CESM2 | 288 × 192 longitude/latitude; 32 levels; top level 2.25 hPa | Prescribed (other) | Historical SSP2-4.5 SSP5-8.5 | Danabasoglu (2019a) Danabasoglu (2019b) |
CESM2-WACCM | 144 × 96 longitude/latitude; 70 levels; top level 4.5 × 10−6 hPa | Interactive chemistry | Historical SSP2-4.5 SSP5-8.5 | Danabasoglu (2019c) Danabasoglu (2019d) |
CNRM-CM6-1 | T127; Gaussian Reduced with 24572 grid points in total distributed over 128 latitude circles (with 256 grid points per latitude circle between 30°N and 30°S reducing to 20 grid points per latitude circle at 88.9°N and 88.9°S); 91 levels; top level 78.4 km | Simplified online scheme | Historical SSP2-4.5 SSP5-8.5 | Voldoire (2018) Voldoire (2019) |
CNRM-ESM2-1 | T127; Gaussian Reduced with 24572 grid points in total distributed over 128 latitude circles (with 256 grid points per latitude circle between 30°N and 30°S reducing to 20 grid points per latitude circle at 88.9°N and 88.9°S); 91 levels; top level 78.4 km | Interactive chemistry | Historical SSP2-4.5 SSP5-8.5 | Seferian (2018) Seferian (2019) |
E3SM-1-0 | Cubed sphere spectral-element grid; 5400 elements with p=3; 1° average grid spacing; 90 × 90 × 6 longitude/latitude/cubeface; 72 levels; top level 0.1 hPa | Simplified online scheme | Historical | Bader et al. (2019) |
FGOALS-g3 | 180 × 80 longitude/latitude; 26 levels; top level 2.19 hPa | Prescribed (CMIP6 dataset) | Historical SSP2-4.5 SSP5-8.5 | Li (2019) |
GFDL-CM4 | 360 × 180 longitude/latitude; 33 levels; top level 1 hPa | Prescribed (CMIP6 dataset) | Historical SSP2-4.5 SSP5-8.5 | Guo et al. (2018a) Guo et al. (2018b) |
GFDL-ESM4 | 360 × 180 longitude/latitude; 49 levels; top level 1 Pa | Interactive chemistry | Historical SSP2-4.5 SSP5-8.5 | Krasting et al. (2018) John et al. (2018) |
IPSL-CM6A-LR | 144 × 143 longitude/latitude; 79 levels; top level 80 km | Prescribed (CMIP6 dataset) | Historical SSP2-4.5 SSP5-8.5 | Boucher et al. (2018) Boucher et al. (2019) |
MRI-ESM2-0 | 192 × 96 longitude/latitude; 80 levels; top level 0.01 hPa | Interactive chemistry | Historical SSP2-4.5 SSP5-8.5 | Yukimoto et al. (2019a) Yukimoto et al. (2019b) |
SAM0-UNICON | 288 × 192 longitude/latitude; 30 levels; top level ~2 hPa | Prescribed (CMIP6 dataset) | Historical | Park and Shin (2019) |
UKESM1-0-LL | 192 × 144 longitude/latitude; 85 levels; top level 85 km | Interactive chemistry | Historical SSP2-4.5 SSP5-8.5 | Tang et al. (2019) Good et al. (2019) |