Why is Lower Stratospheric Ozone Not Recovering?
Lead Research Organisation:
University of Leeds
Department Name: School of Earth and Environment
Abstract
Depletion of stratospheric ozone allows larger doses of harmful solar ultraviolet (UV) radiation to reach the surface leading to increases in skin cancer and cataracts in humans and other impacts, such as crop damage. Ozone also affects the Earth's radiation balance and, in particular, ozone depletion in the lower stratosphere (LS) exerts an important climate forcing. While most long-lived ozone-depleting substances (ODSs, e.g. chlorofluorocarbons, CFCs) are now controlled by the United Nations Montreal Protocol and their abundances are slowly declining, there remains significant uncertainty surrounding the rate of ozone layer recovery. Although signs of recovery have been detected in the upper stratosphere and the Antarctic, this is not the case for the lower stratosphere at middle and low latitudes. In fact, contrary to expectations, ozone in this extrapolar lower stratosphere has continued to decrease (by up to 5% since 1998). The reason(s) for this are not known, but suggested causes include changes in atmospheric dynamics or the increasing abundance of short-lived reactive iodine and chlorine species. We will investigate the causes of this ongoing depletion using comprehensive modelling studies and new targeted observations of the short-lived chlorine substances in the lower stratosphere.
While the Montreal Protocol has controlled the production of long-lived ODSs, this is not the case for halogenated very short-lived substances (VSLS, lifetimes <6 months), based on the belief that they would not be abundant or persistent enough to have an impact. Recent observations suggest otherwise, with notable increases in the atmospheric abundance of several gases (CH2Cl2, CHCl3), due largely to growth in emissions from Asia. A major US aircraft campaign based in Japan in summer 2021 will provide important new information on how these emissions of short-lived species reach the stratosphere via the Asian Summer Monsoon (ASM). UEA will supplement the ACCLIP campaign by making targeted surface observations in Taiwan and Malaysia which will help to constrain chlorine emissions.
The observations will be combined with detailed and comprehensive 3-D modelling studies at Leeds and Lancaster, who have world-leading expertise and tools for the study of atmospheric chlorine and iodine. The modelling will use an off-line chemical transport model (CTM), ideal for interpreting observations, and a coupled chemistry-climate model (CCM) which is needed to study chemical-dynamical feedbacks and for future projections. Novel observations on how gases are affected by gravitational separation will be used to test the modelled descriptions of variations in atmospheric circulation. The CTM will also be used in an 'inverse' mode to trace back the observations of anthropogenic VSLS to their geographical source regions.
The models will be used to quantify the flux of short-lived chlorine and iodine species to the stratosphere and to determine their impact on lower stratospheric ozone trends. The impact of dynamical variability will be quantified using the CTM and the drivers of this determined using the CCM. The model results will be analysed using the same statistical models used to derive the decreasing trend in ozone from observations, including the Dynamical Linear Model (DLM). Overall, the results of the model experiments will be synthesised into an understanding of the ongoing decrease in lower stratospheric ozone. This information will then be used to make improved future projections of how ozone will evolve, which will feed through to the policy-making process (Montreal Protocol) with the collaboration of expert partners. The results of the project will provide important information for future international assessments e.g. WMO/UNEP and IPCC reports.
While the Montreal Protocol has controlled the production of long-lived ODSs, this is not the case for halogenated very short-lived substances (VSLS, lifetimes <6 months), based on the belief that they would not be abundant or persistent enough to have an impact. Recent observations suggest otherwise, with notable increases in the atmospheric abundance of several gases (CH2Cl2, CHCl3), due largely to growth in emissions from Asia. A major US aircraft campaign based in Japan in summer 2021 will provide important new information on how these emissions of short-lived species reach the stratosphere via the Asian Summer Monsoon (ASM). UEA will supplement the ACCLIP campaign by making targeted surface observations in Taiwan and Malaysia which will help to constrain chlorine emissions.
The observations will be combined with detailed and comprehensive 3-D modelling studies at Leeds and Lancaster, who have world-leading expertise and tools for the study of atmospheric chlorine and iodine. The modelling will use an off-line chemical transport model (CTM), ideal for interpreting observations, and a coupled chemistry-climate model (CCM) which is needed to study chemical-dynamical feedbacks and for future projections. Novel observations on how gases are affected by gravitational separation will be used to test the modelled descriptions of variations in atmospheric circulation. The CTM will also be used in an 'inverse' mode to trace back the observations of anthropogenic VSLS to their geographical source regions.
The models will be used to quantify the flux of short-lived chlorine and iodine species to the stratosphere and to determine their impact on lower stratospheric ozone trends. The impact of dynamical variability will be quantified using the CTM and the drivers of this determined using the CCM. The model results will be analysed using the same statistical models used to derive the decreasing trend in ozone from observations, including the Dynamical Linear Model (DLM). Overall, the results of the model experiments will be synthesised into an understanding of the ongoing decrease in lower stratospheric ozone. This information will then be used to make improved future projections of how ozone will evolve, which will feed through to the policy-making process (Montreal Protocol) with the collaboration of expert partners. The results of the project will provide important information for future international assessments e.g. WMO/UNEP and IPCC reports.
Organisations
- University of Leeds (Lead Research Organisation)
- Kyungpook National University (Project Partner)
- University of Malaya (Project Partner)
- Delft University of Technology (Project Partner)
- NCAR (Project Partner)
- University of Miami (Project Partner)
- University of California, San Diego (Project Partner)
- Nat Oceanic and Atmos Admin NOAA (Project Partner)
- Heidelberg University (Project Partner)
- Academia Sinica Taiwan (Project Partner)
- National Institute for Env Studies NIES (Project Partner)
- NASA (Project Partner)
Publications
Dhomse S
(2023)
Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets
in Earth System Science Data
Raymond N
(2026)
Twenty-One Years of Global Atmospheric Chlorine Inventories From Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) Measurements
in Journal of Geophysical Research: Atmospheres
Pazmiño A
(2023)
Trends in polar ozone loss since 1989: potential sign of recovery in the Arctic ozone column
in Atmospheric Chemistry and Physics
Saiz-Lopez A
(2025)
The influence of short-lived halogens on atmospheric chemistry and climate.
in Nature
Zhou X
(2023)
The Influence of Internal Climate Variability on Stratospheric Water Vapor Increases After Large-Magnitude Explosive Tropical Volcanic Eruptions
in Geophysical Research Letters
Li Y
(2026)
The impact of rocket-emitted chlorine on stratospheric ozone
in Atmospheric Chemistry and Physics
Li Y
(2024)
The impact of El Niño-Southern Oscillation on the total column ozone over the Tibetan Plateau
in Atmospheric Chemistry and Physics
Li Y
(2023)
Quantifying stratospheric ozone trends over 1984-2020: a comparison of ordinary and regularized multivariate regression models
in Atmospheric Chemistry and Physics
Feng W
(2023)
Potential Stratospheric Ozone Depletion Due To Iodine Injection From Small Satellites
in Geophysical Research Letters
Chipperfield M
(2023)
Opinion: Stratospheric Ozone - Depletion, Recovery and New Challenges
Chipperfield M
(2024)
Opinion: Stratospheric ozone - depletion, recovery and new challenges
in Atmospheric Chemistry and Physics
Chipperfield MP
(2025)
Ongoing large ozone depletion in the polar lower stratospheres: the role of increased water vapour.
in Faraday discussions
Hossaini R
(2024)
On the atmospheric budget of 1,2-dichloroethane and its impact on stratospheric chlorine and ozone (2002-2020)
in Atmospheric Chemistry and Physics
Arosio C
(2024)
Investigating Zonal Asymmetries in Stratospheric Ozone Trends From Satellite Limb Observations and a Chemical Transport Model
in Journal of Geophysical Research: Atmospheres
Pyle JA
(2022)
Integrated ozone depletion as a metric for ozone recovery.
in Nature
Chrysanthou A
(2025)
Hemispheric Asymmetry in Stratospheric Trends of HCl and Ozone: Impact of Chemical Feedback on Ozone Recovery
in Journal of Geophysical Research: Atmospheres
Hart L
(2026)
Growth in Production and Environmental Deposition of Trifluoroacetic Acid Due To Long-Lived CFC Replacements and Anesthetics
in Geophysical Research Letters
Dowd E
(2024)
First validation of high-resolution satellite-derived methane emissions from an active gas leak in the UK
in Atmospheric Measurement Techniques
Abalos M
(2026)
Evaluation of stratospheric transport in three generations of Chemistry-Climate Models
in Atmospheric Chemistry and Physics
Pardo Cantos I
(2022)
Determination and analysis of time series of CFC-11 (CCl 3 F) from FTIR solar spectra, in situ observations, and model data in the past 20 years above Jungfraujoch (46°N), Lauder (45°S), and Cape Grim (40°S) stations
in Environmental Science: Atmospheres
Bednarz E
(2023)
Description and evaluation of the new UM-UKCA (vn11.0) Double Extended Stratospheric-Tropospheric (DEST vn1.0) scheme for comprehensive modelling of halogen chemistry in the stratosphere
in Geoscientific Model Development
Dowd E
(2023)
Decreasing seasonal cycle amplitude of methane in the northern high latitudes being driven by lower-latitude changes in emissions and transport
in Atmospheric Chemistry and Physics
Chipperfield M
(2022)
Comment on "Observation of large and all-season ozone losses over the tropics" [AIP Adv. 12, 075006 (2022)]
in AIP Advances
Bednarz E
(2023)
Atmospheric impacts of chlorinated very short-lived substances over the recent past - Part 2: Impacts on ozone
in Atmospheric Chemistry and Physics
Bednarz E
(2022)
Atmospheric impacts of chlorinated very short-lived substances over the recent past - Part 1: Stratospheric chlorine budget and the role of transport
in Atmospheric Chemistry and Physics
An M
(2023)
Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions.
in Environmental science & technology
Zhou X
(2024)
Antarctic Vortex Dehydration in 2023 as a Substantial Removal Pathway for Hunga Tonga-Hunga Ha'apai Water Vapor
in Geophysical Research Letters
Dhomse S
(2022)
A single-peak-structured solar cycle signal in stratospheric ozone based on Microwave Limb Sounder observations and model simulations
in Atmospheric Chemistry and Physics
| Description | We have shown that although the ozone layer is showing signs of a long-term recovery, there are still many events which are causing short-term episodes of ozone depletion. These events include changing circulation and volcanic eruptions. |
| Exploitation Route | To motivate need to monitor the environment. |
| Sectors | Environment |
| URL | https://tomcat.leeds.ac.uk |
| Description | Communication to media on many aspects of ozone depletion related to Hunga Tonga, space debris, etc. |
| First Year Of Impact | 2022 |
| Sector | Environment |
| Impact Types | Cultural Societal |
| Description | WMO/UNEP Ozone Assessment 2026 |
| Geographic Reach | Multiple continents/international |
| Policy Influence Type | Participation in a guidance/advisory committee |
| URL | https://ozone.unep.org/system/files/documents/SAP_Presentation_36MOP_31Oct2024.pdf |
| Description | Investigating HALocarbon impacts on the global Environment |
| Amount | £402,598 (GBP) |
| Funding ID | NE/X003450/1 |
| Organisation | Natural Environment Research Council |
| Sector | Public |
| Country | United Kingdom |
| Start | 12/2022 |
| End | 11/2026 |
| Description | Ozone Recovery from Merged Observational Data and Model Analysis (OREGANO) |
| Amount | € 200,000 (EUR) |
| Funding ID | 4000137112/22/I-AG |
| Organisation | European Space Agency |
| Sector | Public |
| Country | France |
| Start | 03/2022 |
| End | 11/2024 |
| Title | Machine Learning Models for Atmospheric Composition |
| Description | The ML-TOMCAT and TCOM models combine stratospheric limb observations and output from the TOMCAT 3D chemical transport model to produce long-term, gap-free global datasets of trace gases. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2021 |
| Provided To Others? | Yes |
| Impact | Improved model testing and retrievals. |
| URL | https://tomcat.leeds.ac.uk/tomcat/tcom/ |
| Title | TCOM-CFC12 : TOMCAT CTM and Occultation measurement-based CFC12 profile data set |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 2000-2023 period. Collocated CFC12 (CF2Cl2) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate CFC12 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean CFC-12 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmcfc12_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmcfc12_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attachecd pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates will be submitted to ESSD. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.12548527 |
| Title | TCOM-CFC12 : TOMCAT CTM and Occultation measurement-based CFC12 profile data set |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 2000-2023 period. Collocated CFC12 (CF2Cl2) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate CFC12 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean CFC-12 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmcfc12_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmcfc12_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attachecd pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates will be submitted to ESSD. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New daraset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18147392 |
| Title | TCOM-CH4: TOMCAT CTM and Occultation Measurements based daily methane profile data set |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. CH4 Profile Processing and Bias Correction Collocated CH4 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate CH4 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean CH4 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmch4_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmch4_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18197333 |
| Title | TCOM-CH4: TOMCAT CTM and Occultation Measurements based daily methane profile data set |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. CH4 Profile Processing and Bias Correction Collocated CH4 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate CH4 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean CH4 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmch4_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmch4_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.7293739 |
| Title | TCOM-COF2: TOMCAT CTM and Occultation measurement-based COF2 profile data set |
| Description | TCOM-COF2: TOMCAT CTM and Occultation measurement-based Stratospheric TCOM-COF2 profile data set Sandip S. Dhomse School of Earth and Enviro, University of Leeds, Leeds, UK National Centre for Earth Observations, University of Leeds, Leeds, UK email: s.s.dhomse@leeds.ac.uk The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. COF2 Profile Processing and Bias Correction Collocated COF2 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate COF2 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean COF2 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 10 to 35km). zmcof2_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmcof2_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.12551167 |
| Title | TCOM-COF2: TOMCAT CTM and Occultation measurement-based COF2 profile data set |
| Description | TCOM-COF2: TOMCAT CTM and Occultation measurement-based Stratospheric TCOM-COF2 profile data set Sandip S. Dhomse School of Earth and Enviro, University of Leeds, Leeds, UK National Centre for Earth Observations, University of Leeds, Leeds, UK email: s.s.dhomse@leeds.ac.uk The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. COF2 Profile Processing and Bias Correction Collocated COF2 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate COF2 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean COF2 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 10 to 35km). zmcof2_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmcof2_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18201786 |
| Title | TCOM-H2O: TOMCAT CTM and Occultation Measurements based daily zonal stratospheric H2O profile dataset |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. H2O Profile Processing and Bias Correction Collocated H2O profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate H2O volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean H2O profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmh2o_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmh2o_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.7912903 |
| Title | TCOM-H2O: TOMCAT CTM and Occultation Measurements based daily zonal stratospheric H2O profile dataset |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. H2O Profile Processing and Bias Correction Collocated H2O profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate H2O volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean H2O profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmh2o_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmh2o_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18199962 |
| Title | TCOM-HCl : Daily global gap-free stratospheric hydrogen chloride profile data set based on TOMCAT CTM and Occultation Measurements |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 1991-2021 time period. Collocated hydrogen chloride (HCl) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, model-measurement differences are calculated for each zonal bins (46 height levels, 15km to 60km). Separate XGBoost regression models are trained for the differences between TOMCAT and measurements at each level for a given latitude bin. XGBoost model is then used to estimate error corrections for all the TOMCAT grids ( day/night, 2 X11323 time steps). TOMCAT output sampled at 1.30 am and 1.30 pm local time at the equator. Estimated corrections for a given model grid that are added to the original TOMCAT simulated day and night time HCl profiles. Height resolved data are then interpolated on 28-pressure levels (300 - 0.1hPa). For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HCl profiles on height (15-60 km) and pressure (300-0.1 hPa) levels: zmhcl_TCOM_hlev_T2Dz_1991_2021.nc - height level data (15 to 60 km) zmhcl_TCOM_plev_T2Dz_1991_2021.nc - pressure level data (300 to 0.1 hPa) Daily 3D profiles on height and pressure levels would be made available upon request |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | Has been used to test models and constrain retrievals. |
| URL | https://zenodo.org/record/7608194 |
| Title | TCOM-HCl : Daily global gap-free stratospheric hydrogen chloride profile data set based on TOMCAT CTM and Occultation Measurements |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 1991-2021 time period. Collocated hydrogen chloride (HCl) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, model-measurement differences are calculated for each zonal bins (46 height levels, 15km to 60km). Separate XGBoost regression models are trained for the differences between TOMCAT and measurements at each level for a given latitude bin. XGBoost model is then used to estimate error corrections for all the TOMCAT grids ( day/night, 2 X11323 time steps). TOMCAT output sampled at 1.30 am and 1.30 pm local time at the equator. Estimated corrections for a given model grid that are added to the original TOMCAT simulated day and night time HCl profiles. Height resolved data are then interpolated on 28-pressure levels (300 - 0.1hPa). For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HCl profiles on height (15-60 km) and pressure (300-0.1 hPa) levels: zmhcl_TCOM_hlev_T2Dz_1991_2021.nc - height level data (15 to 60 km) zmhcl_TCOM_plev_T2Dz_1991_2021.nc - pressure level data (300 to 0.1 hPa) Daily 3D profiles on height and pressure levels would be made available upon request |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/record/7608193 |
| Title | TCOM-HCl : TOMCAT CTM and Occultation Measurements based HCl profile data set |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse et al. (2021, 2022), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. HCl Profile Processing and Bias Correction Collocated HCl profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate HCl volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HCl profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmhcl_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmhcl_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publication This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18184430 |
| Title | TCOM-HF : TOMCAT CTM and Occultation Measurements based HF profile data set |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. HF Profile Processing and Bias Correction Collocated HF profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate HF volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HF profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmhf_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmhf_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18184779 |
| Title | TCOM-HF : Daily global gap-free stratospheric hydrogen fluoride (HF) profile data set based on TOMCAT CTM and Occultation Measurements |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 1991-2021 time period. Collocated hydrogen fluoride (HF) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, model-measurement differences are calculated for each zonal bins (46 height levels, 15km to 60km). Separate XGBoost regression models are trained for the differences between TOMCAT and measurements at each level for a given latitude bin. XGBoost model is then used to estimate error corrections for all the TOMCAT grids ( day/night, 2 X11323 time steps). TOMCAT output sampled at 1.30 am and 1.30 pm local time at the equator. Estimated corrections for a given model grid that are added to the original TOMCAT simulated day and night time hydrogen fluoride profiles. Height resolved data are then interpolated on 28-pressure levels (300 - 0.1hPa). For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean hydrogen fluoride profiles on height (15-60 km) and pressure (300-0.1 hPa) levels: zmhf_TCOM_hlev_T2Dz_1991_2021.nc - height level data (15 to 60 km) zmhf_TCOM_plev_T2Dz_1991_2021.nc - pressure level data (300 to 0.1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | Has been used to test models and constrain retrievals. |
| URL | https://zenodo.org/record/7607564 |
| Title | TCOM-HF : Daily global gap-free stratospheric hydrogen fluoride (HF) profile data set based on TOMCAT CTM and Occultation Measurements |
| Description | Methodology: TOMCAT simulation is performed at T64L32 resolution for the 1991-2021 time period. Collocated hydrogen fluoride (HF) profiles are divided in five latitude bins: SH polar (90S-50S), SH mid-lat (70S-20S), tropics (40S-40N), NH mid-lat (20N-70N) and NH polar (50N-90N). Initially, model-measurement differences are calculated for each zonal bins (46 height levels, 15km to 60km). Separate XGBoost regression models are trained for the differences between TOMCAT and measurements at each level for a given latitude bin. XGBoost model is then used to estimate error corrections for all the TOMCAT grids ( day/night, 2 X11323 time steps). TOMCAT output sampled at 1.30 am and 1.30 pm local time at the equator. Estimated corrections for a given model grid that are added to the original TOMCAT simulated day and night time hydrogen fluoride profiles. Height resolved data are then interpolated on 28-pressure levels (300 - 0.1hPa). For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean hydrogen fluoride profiles on height (15-60 km) and pressure (300-0.1 hPa) levels: zmhf_TCOM_hlev_T2Dz_1991_2021.nc - height level data (15 to 60 km) zmhf_TCOM_plev_T2Dz_1991_2021.nc - pressure level data (300 to 0.1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/record/7607563 |
| Title | TCOM-HNO3 : TOMCAT CTM and Occultation Mesurement based daily HNO3 profile data set |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. HNO3 Profile Processing and Bias Correction Collocated HNO3 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate HNO3 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HNO3 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmhno3_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmhno3_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18199002 |
| Title | TCOM-HNO3 : TOMCAT CTM and Occultation Mesurement based daily HNO3 profile data set |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. HNO3 Profile Processing and Bias Correction Collocated HNO3 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate HNO3 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean HNO3 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmhno3_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmhno3_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.15664974 |
| Title | TCOM-N2O: TOMCAT CTM and Occultation Measurements based daily zonal nitrous oxide profile dataset |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. N2O Profile Processing and Bias Correction Collocated N2O profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate N2O volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean N2O profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmn2o_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmn2o_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.7386000 |
| Title | TCOM-N2O: TOMCAT CTM and Occultation Measurements based daily zonal nitrous oxide profile dataset |
| Description | Methodology: The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. N2O Profile Processing and Bias Correction Collocated N2O profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate N2O volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean N2O profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmn2o_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmn2o_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18197444 |
| Title | TCOM-O3: TOMCAT CTM and Occultation Measurements based daily ozone profile data set |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. O3 Profile Processing and Bias Correction Collocated O3 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate O3 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean O3 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmo3_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmo3_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| URL | https://zenodo.org/doi/10.5281/zenodo.7684576 |
| Title | TCOM-O3: TOMCAT CTM and Occultation Measurements based daily ozone profile data set |
| Description | The TOMCAT simulation was conducted at a T64L32 resolution, consistent with previous work by Dhomse and Chipperfield (2023), covering the period from 2000 to 2024. These simulations utilized ERA-5 reanalysis data. O3 Profile Processing and Bias Correction Collocated O3 profiles are organized into five distinct latitude bins: NH polar: 90°N - 50°N NH mid-lat: 20°N - 70°N Tropics: 40°S - 40°N SH mid-lat: 70°S - 20°S SH polar: 90°S - 50°S Initially, TOMCAT tracers are interpolated on the ACE FTS height (1km to 50km) Separate XGBoost regression models are trained to predict ACE FTS measurements for a given altitude /latitude bin if more than 2000 measurements are available. XGBoost model is then used to estimate O3 volume mixing ratios for all the TOMCAT grids. Height resolved data are then interpolated on 22-pressure levels. For overlapping latitude bins, we use averages and then calculate daily zonal mean values. For more details see attached presentation. Dataset also includes two files containing daily mean zonal mean O3 profiles on height (1-50 km) and pressure (300-1 hPa) - 22 levels (9132 days/64 latitudes). Files also include uncertainties estimated using quantile regression and uncertainty = NaN means data is from TOMCAT CTM (scientifically useful range 5 to 25km). zmo3_tcom_hlev_2000-2024_V2.0.nc - height level data (1 to 50 km) zmo3_tcom_plev_2000-2024_V2.0.nc - pressure level data (300 to 1 hPa) Daily 3D profiles on height and pressure levels would be made available on request. Xarrays "resample" can be used to get monthly means. (Attached pdf file gives more details. This data set improves from our previous methodology (Dhomse and Chipperfield, 2023, ESSD) and manuscript describing to those updates is submitted to ESSD as Dhomse and Chipperfield, 2026. Reference Publications This methodology, incorporating only ACE-FTS data and various minor algorithmic developments, is based on the following publication: Dhomse, S. S. and Chipperfield, M. P.: Using machine learning to construct TOMCAT model and occultation measurement-based stratospheric methane (TCOM-CH4) and nitrous oxide (TCOM-N2O) profile data sets, Earth Syst. Sci. Data, 15, 5105-5120, https://doi.org/10.5194/essd-15-5105-2023, 2023 Dhomse, S. S. and Chipperfield, M. P.: TCOM-CFC11 and TCOM-CFC12: A Gap-Free, Observationally Constrained Global Dataset of Stratospheric CFC11 and CFC12 Profiles (V2)., submitted to Earth Syst. Sci. Data, 2026 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2026 |
| Provided To Others? | Yes |
| Impact | New dataset |
| URL | https://zenodo.org/doi/10.5281/zenodo.18199586 |
| Title | TOMCAT CTM simulated ozone profiles using NRL2, SATIRE and SORCE solar fluxes |
| Description | Individual file contain TOMCAT CTM simulated ozone profiles from five model simulations analysed in the following publication. Briefly, vmro3_T2Mz_TOMCAT_A_NRL2_2005-2020.nc contain ozone profiles from the control simulation that uses ERA5 dynamical forcing fields and NRL V2 solar fluxes vmro3_T2Mz_TOMCAT_B_SATIRE_2005-2020.nc and vmro3_T2Mz_TOMCAT_C_SORCE_2005-2020.nc contain ozone profiles from a simulations that are similar to the control simulation but with SATIRE and SORCE solar fluxes vmro3_T2Mz_TOMCAT_D_SFix_2005-2020.nc has ozone profiles from simulation that is similar to the control simulation but with fixed solar fluxes, whereas vmro3_T2Mz_TOMCAT_E_DFix_2005-2020.nc also contain ozone profiles from a simulation where model uses annually repeating dynamical fields. Dhomse, S. S., Chipperfield, M. P., Feng, W., Hossaini, R., Mann, G. W., Santee, M. L., and Weber, M.: A Single-Peak-Structured Solar Cycle Signal in Stratospheric Ozone based on Microwave Limb Sounder Observations and Model Simulations, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2021-663, in review, 2021. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2022 |
| Provided To Others? | Yes |
| Impact | Improved understanding of solar - ozone interactions. |
| URL | https://zenodo.org/record/5875190 |
| Title | TOMCAT/SLIMCAT 3D Model |
| Description | Detailed 3-D model of atmospheric chemistry and aerosols. The model was initially developed around 20 years ago, but multiple projects have led to further developing and testing of specific routines and parameterisations. |
| Type Of Material | Computer model/algorithm |
| Provided To Others? | Yes |
| Impact | Many peer-reviewed publications. See website. |
| URL | https://tomcat.leeds.ac.uk/tomcat/ |