During polar front intrusion episodes, air masses from the Arctic not only reduce the temperature but also the ozone concentration in the mid-latitudes.
We find that the inclusion of polar halogens (chlorine, bromine, iodine) in our climate model is necessary to reproduce ozone levels and seasonality in the Arctic, particularly in spring. When cold Arctic air masses descend to mid-latitudes, they are halogen-enriched and ozone-depleted. In addition, halogen-mediated catalytic ozone-destroying reactions continue to operate within the cold air mass during southward transport. This phenomenon causes significant reductions in background ozone over large regions of Canada, the United States, and Europe.
These results have been published in the journal PNAS:
Rafael P. Fernandez, Lucas Berná, Orlando Tomazzeli, Anoop Sharad Mahajan, Qinyi Li, Douglas E. Kinnison, Siyuan Wang, Jean-Francois Lamarque, Simone Tilmes, Henrik Skov, Carlos A. Cuevas and Alfonso Saiz-Lopez. Arctic halogens reduce ozone in the northern mid-latitudes. Proceedings of the National Academy of Sciences. DOI: www.pnas.org/doi/10.1073/pnas.2401975121