By Patrick Cullis, NOAA Global Monitoring Laboratory scientist
This year’s measurements took some twists and turns as NOAA’s ozonesondes launched from the South Pole encountered somewhat surprising layers of higher ozone in the main depletion region, while simultaneously aligning with lower ozone above and below the 14-21km depletion region. (Reminder: the 14-21km layer is the primary region for ozone depletion.)
That resulted in this year’s measurements falling right in the middle of the pack, becoming the 19th lowest annual minimum measurement of the ozone layer above the South Pole over the past 38 years.
In the above graph, you can see that dynamics and natural variability drive much of each year’s individual minimum, while we may see glimpses of recovery in the fact we avoided breaking records during the “ideal” ozone hole conditions of extremely stable polar vortexes in 2020, 2021, and 2022.
We had expected to see low ozone measurements as a result of additional water vapor making its way into the vortex following the 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption. That water vapor may have had an effect early in the ozone hole’s formation, as it appears depletion began a little sooner than normal. But further examination will be needed to determine the full impact of the Hunga Tonga-Hunga Ha’apai eruption.
Finally, a shout out to our amazing techs stationed at the Amundsen-Scott South Pole Station for another exciting round of measurements during this ozone depletion season.