Stratospheric dynamics modulates ozone layer response to molecular oxygen variations

Frontiers in Earth Science

Earth Science

Thomas Peter¹  Gabriel Chiodo¹  Andrea Stenke²  Iga Józefiak³  Harald Rieder⁴  Jan Sedlacek⁵  Tatiana Egorova⁵  Timofei Sukhodolov⁶  Eugene Rozanov⁷ 

[1] Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland;Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland;Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland;Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland;Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland;Institute of Meteorology and Climatology, University of Natural Resources and Life Sciences, Vienna, Austria;Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Davos, Switzerland;Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Davos, Switzerland;Ozone Layer and Upper Atmosphere Research Laboratory, Saint Petersburg State University, Saint Petersburg, Russia;Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Davos, Switzerland;Ozone Layer and Upper Atmosphere Research Laboratory, Saint Petersburg State University, Saint Petersburg, Russia;Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland;

关键词: stratospheric dynamics;    ozone layer;    O/O relationship;    chemistry-dynamics feedback;    Phanerozoic Eon;   

DOI  :  10.3389/feart.2023.1239325

 received in 2023-06-13, accepted in 2023-08-24,  发布年份 2023

来源: Frontiers

【 摘 要 】

Photolysis of molecular oxygen (O2) sustains the stratospheric ozone layer and is thereby protecting living organisms on Earth by absorbing harmful ultraviolet radiation. In the past, atmospheric O2 levels were not constant, and their variations are thought to be responsible for the extinction of some species due to the thinning of the ozone layer. Over the Phanerozoic Eon (last ∼500 Mio years), the O2 volume mixing ratio ranged between 10% and 35% depending on the level of photosynthetic activity of plants and oceans. Previous estimates, mostly performed by simplified 1-D models, showed different ozone (O3) responses to atmospheric O2 changes within this range, such as monotonically positive or negative correlations, or displaying a maximum in the O3 column around a certain O2 level. Here, we assess the ozone layer sensitivity to atmospheric O2 varying between 5% and 40% with a state-of-the-art 3-D chemistry-climate model (CCM). Our findings show that the O3 layer thickness maximizes around the current mixing ratio of O2, 21% ± 5%, while lower or higher levels of O2 result globally in a reduction of total column O3. At low latitudes, the total column O3 is less sensitive to O2 variations, because of the “self-healing” effect, namely, a vertical dipole in the tropical ozone response. Mid- and high-latitude O3 columns that are largely affected by transport of O3 from the tropics, however, are much more sensitive to O2 with changes up to 20 DU even for small (±5%) O2 perturbations. We show that these variations are largely driven by the radiative impact of O3 on stratospheric temperatures and on the strength of the Brewer-Dobson circulation (BDC), indicating chemistry-radiation-transport feedback. High O2 cases result in an acceleration of the BDC and vice versa, which always works in favor of the negative part of the O3 anomaly dipole in the tropics being more effectively transported to the mid- and high-latitudes than the positive one. Although there are other factors strongly influencing O3/O2 relationship on the Phanerozoic Eon timescales that have not been considered here, our results and the presented mechanism bring useful insights for other studies focusing on the long-term O3/O2 relationship.

【 授权许可】

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Copyright © 2023 Józefiak, Sukhodolov, Egorova, Chiodo, Peter, Rieder, Sedlacek, Stenke and Rozanov.