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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-87
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Feb 2018
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Atmospheric Chemistry and Physics (ACP).
Estimates of Ozone Return Dates from Chemistry-Climate Model Initiative Simulations
Sandip Dhomse1, Douglas Kinnison2, Martyn P. Chipperfield1, Irene Cionni3, Michaela Hegglin4, N. Luke Abraham5,6, Hideharu Akiyoshi7, Alex T. Archibald5,6, Ewa M. Bednarz5, Slimane Bekki8, Peter Braesicke9, Neal Butchart10, Martin Dameris11, Makoto Deushi12, Stacy Frith13, Steven C. Hardiman10, Birgit Hassler11, Larry W. Horowitz14, Rong-Ming Hu8, Patrick Jöckel11, Beatrice Josse15, Oliver Kirner16, Stefanie Kremser17, Ulrike Langematz18, Jared Lewis17, Marion Marchand8, Meiyun Lin14,19, Eva Mancini20, Virginie Marécal15, Martine Michou15, Olaf Morgenstern21, Fiona M. O'Connor10, Luke Oman13, Giovanni Pitari22, David A. Plummer23, John A. Pyle5,6, Laura E. Revell24,25, Eugene Rozanov25,26, Robyn Schofield27,28, Andrea Stenke25, Kane Stone27,28,a, Kengo Sudo29,30, Simone Tilmes2, Daniele Visioni20, Yousuke Yamashita7,30, and Guang Zeng21 1School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
2National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA
3Agenzia Nazionale per le Nuove Tecnologie, l'energia e lo Sviluppo Economica Sostenible (ENEA), Bologna, Italy
4Department of Meteorology, University of Reading, Reading, UK
5Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
6National Centre for Atmospheric Science, UK
7National Institute for Environmental Studies (NIES), Tsukuba, 305-8506 Japan
8IPSL/CNRS, 75252 Paris, France
9IMK-ASF, KIT, Karlsruhe, Germany
10Met Office Hadley Centre, Exeter, UK
11Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphare, Oberpfaffenhofen, Germany
12Meteorological Research Institute (MRI), Tsukuba, Japan
13NASA/GSFC, USA
14NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA
15Meteo-France, Toulouse, France
16Steinbuch Centre for Computing (SCC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
17Bodeker Scientific, Alexandra, New Zealand
18Institut für Meteorologie, Freie Universitat Berlin, Berlin, Germany
19Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08540, USA
20Dept. of Physical and Chemical Sciences & Center of Excellence CETEMPS, Universita del l'Aquila, Italy
21NIWA, New Zealand
22Department of Physical and Chemical Sciences, Universitat dell'Aquila, Italy
23Climate Research Division, Environment and Climate Change Canada, Montreal, Canada
24Bodeker Scientific, Alexandra, New Zealand
25ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland
26Physikalisch-Meteorologisches Observatorium Davos World Radiation Centre, Davos Dorf, Switzerland
27School of Earth Sciences, University of Melbourne, Melbourne, Australia
28ARC Centre of Excellence for Climate System Science, Sydney, Australia
29Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
30Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, 236-0001 Japan
anow at: Massachusetts Institute of Technology (MIT), Boston, Massachusetts, USA
Abstract. We analyse simulations performed for the Chemistry-Climate Model Initiative (CCMI) to estimate the return dates of the stratospheric ozone layer from depletion caused by anthropogenic stratospheric chlorine and bromine. We consider a total of 155 simulations from 20 models, including a range of sensitivity studies which examine the impact of climate change on ozone recovery. For the control simulations (unconstrained by nudging towards analysed meteorology) there is a large spread (±20 DU in the global average) in the predictions of the absolute ozone column. Therefore, the model results need to be adjusted for biases against historical data. Also, the interannual variability in the model results need to be smoothed in order to provide a reasonably narrow estimate of the range of ozone return dates. Consistent with previous studies, but here for a Representative Concentration Pathway (RCP) of 6.0, these new CCMI simulations project that global total column ozone will return to 1980 values in 2047 (with a 1-σ uncertainty of 2042–2052). At Southern Hemisphere mid-latitudes column ozone is projected to return to 1980 values in 2046 (2042–2050), and at Northern Hemisphere mid-latitudes in 2034 (2024–2044). In the polar regions, the return dates are 2062 (2055–2066) in the Antarctic in October and 2035 (2025–2040) in the Arctic in March. The earlier return dates in the NH reflect the larger sensitivity to dynamical changes. Our estimates of return dates are later than those presented in the 2014 Ozone Assessment by approximately 5–15 years, depending on the region. In the tropics only around half the models predict a return to 1980 values, at around 2040, while the other half do not reach this value. All models show a negative trend in tropical total column ozone towards the end of the 21st century. The CCMI models generally agree in their simulation of the time evolution of stratospheric chlorine, which is the main driver of ozone loss and recovery. However, there are a few outliers which show that the multi-model mean results for ozone recovery are not as tightly constrained as possible. Throughout the stratosphere the spread of ozone return dates to 1980 values between models tends to correlate with the spread of the return of inorganic chlorine to 1980 values. In the upper stratosphere, greenhouse gas-induced cooling speeds up the return by about 10–20 years. In the lower stratosphere, and for the column, there is a more direct link in the timing of the return dates, especially for the large Antarctic depletion. Comparisons of total column ozone between the models is affected by different predictions of the evolution of tropospheric ozone within the same scenario, presumably due to differing treatment of tropospheric chemistry. Therefore, for many scenarios, clear conclusions can only be drawn for stratospheric ozone columns rather than the total column. As noted by previous studies, the timing of ozone recovery is affected by the evolution of N2O and CH4. However, the effect in the simulations analysed here is small and at the limit of detectability from the few realisations available for these experiments compared to internal model variability. The large increase in N2O given in RCP 6.0 extends the ozone return globally by ~ 15 years relative to N2O fixed at 1960 abundances, mainly because it allows tropical column ozone to be depleted. The effect in extratropical latitudes is much smaller. The large increase in CH4 given in the RCP 8.5 scenario compared to RCP 6.0 also changes ozone return by ~ 15 years, again mainly through its impact in the tropics. For future assessments of single forcing or combined effects of CO2, CH4, and N2O on the stratospheric column ozone return dates, this work suggests that is more important to have multi-member (at least 3) ensembles for each scenario from each established participating model, rather than a large number of individual models.
Citation: Dhomse, S., Kinnison, D., Chipperfield, M. P., Cionni, I., Hegglin, M., Abraham, N. L., Akiyoshi, H., Archibald, A. T., Bednarz, E. M., Bekki, S., Braesicke, P., Butchart, N., Dameris, M., Deushi, M., Frith, S., Hardiman, S. C., Hassler, B., Horowitz, L. W., Hu, R.-M., Jöckel, P., Josse, B., Kirner, O., Kremser, S., Langematz, U., Lewis, J., Marchand, M., Lin, M., Mancini, E., Marécal, V., Michou, M., Morgenstern, O., O'Connor, F. M., Oman, L., Pitari, G., Plummer, D. A., Pyle, J. A., Revell, L. E., Rozanov, E., Schofield, R., Stenke, A., Stone, K., Sudo, K., Tilmes, S., Visioni, D., Yamashita, Y., and Zeng, G.: Estimates of Ozone Return Dates from Chemistry-Climate Model Initiative Simulations, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-87, in review, 2018.
Sandip Dhomse et al.
Sandip Dhomse et al.
Sandip Dhomse et al.

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Short summary
We analyse simulations from the Chemistry-Climate Model Initiative (CCMI) to estimate the return dates of the stratospheric ozone layer from depletion by anthropogenic chlorine and bromine. The simulations from 20 models project that global column ozone will return to 1980 values in 2047 (uncertainty range 2042–2052). Return dates in other regions vary depending on factors related to climate change and importance of chlorine and bromine. Column ozone in the tropics may continue to decline.
We analyse simulations from the Chemistry-Climate Model Initiative (CCMI) to estimate the return...
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