On Recent Large Antarctic Ozone Holes and Ozone Recovery Metrics

Area of Science:

• Atmospheric Chemistry
• Climate Science
• Ozone Layer Research

Background:

• The ozone hole, particularly its size and timing, is a critical indicator of stratospheric health.
• Recent years have seen large ozone hole events, raising questions about the pace of recovery.

Purpose of the Study:

• To assess the adherence of recent large ozone hole events to fundamental ozone layer recovery metrics.
• To evaluate the performance of the Whole Atmosphere Chemistry Climate Model in simulating ozone hole dynamics and recovery.

Main Methods:

• Quantification of observed trends in the onset date of the ozone hole.
• Analysis of the size and depth of the September ozone hole over the past decade.
• Comparison of observed trends with simulations from the Whole Atmosphere Chemistry Climate Model.

Main Results:

• Recent large ozone holes, including those in 2015 and 2020, demonstrate a later onset of spring ozone depletion, a key recovery indicator.
• Observed trends in the onset and size of the September ozone hole show good agreement with model predictions.
• A significant reduction in the depth of the September ozone hole has been observed over the last ten years.

Conclusions:

• Intermittent large ozone holes in October-December are probable due to atmospheric dynamics.
• Ozone recovery is evident through delayed onset, reduced September ozone hole size, and decreased depth, reflecting chemical process improvements.