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Volcanic eruptions can contribute to polar ozone depletion when volcanic aerosol propagates into the tropical or polar stratosphere. During the period from 1850 to the present, none of the eruptions of extratropical volcanoes in the Northern Hemisphere was observed in the tropical stratosphere and, therefore, could not contribute to the polar vortex strengthening in the conditions of an increase of the stratospheric equator-to-pole temperature gradient as a result of an increase of the tropical stratospheric temperature. However, this is possible during mid-latitude volcanic eruptions with VEI ≥ 6 and during high-latitude volcanic eruptions with VEI ≥ 7. During the period from 1980 to the present, none of the eruptions of extratropical volcanoes in the Northern Hemisphere influenced the intensity of Arctic ozone depletion, since in some cases the ejection of eruption products was outside the polar vortex, and in other cases the height of the ejection was insufficient and the volcanic aerosol was removed from the stratosphere as a result of sedimentation even before the polar vortex formation. However, the effect of extratropical volcanic eruptions on Arctic ozone depletion is possible when the eruption products enter the polar vortex, or when a volcanic aerosol propagates into the polar region before the polar vortex formation with a sufficient lifetime in the stratosphere, determined, in particular, by the height of the ejection.
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