Arctic "ozone hole" in a cold volcanic stratosphere

Area of Science:

• Atmospheric Chemistry
• Stratospheric Science
• Volcanology

Background:

• Volcanic aerosols can form clouds with larger surface areas than Arctic polar stratospheric clouds (PSCs).
• Arctic ozone loss is influenced by processes like chlorine activation and denitrification, which are exacerbated by PSCs.

Purpose of the Study:

• To investigate the impact of volcanic aerosols on springtime Arctic ozone loss.
• To quantify the potential increase in ozone depletion due to volcanic aerosols in the lower stratosphere.

Main Methods:

• Utilized a trajectory cloud-chemistry model to simulate Arctic winter conditions.
• Assessed the effects of volcanic aerosols on chemical ozone loss processes, including chlorine activation and denitrification.

Main Results:

• Volcanic aerosols hinder the formation of large PSC particles responsible for denitrification.
• Volcanic aerosols at lower altitudes, where PSCs do not form, can extend the vertical range of chemical ozone loss.
• Chemical processing on volcanic aerosols could increase springtime column ozone loss by up to 70%.

Conclusions:

• Volcanic aerosols can substantially enhance Arctic ozone loss in the lower stratosphere, independent of denitrification.
• The modeled ozone loss in a volcanic Arctic winter is comparable to projections for a future, colder, nonvolcanic stratosphere.