In 2023, the Antarctic ozone hole reached its maximum size on September 21, NASA and NOAA reported based on their annual satellite and balloon-based measurements.
This hole spans 10 million square miles or 26 million square kilometers, and it stands as the 12th largest single-day ozone hole since records began in 1979. It is also the 16th largest when averaged from September 7 to October 13.
Throughout the peak of the ozone depletion season, from September 7 to October 13, this year's hole averaged 8.9 million square miles (around 23.1 million square kilometers) - roughly the expanse of North America, making it the 16th largest over this period.
Displayed here is the extent and configuration of the ozone hole over the South Pole on September 21, 2023, at its peak, as computed by NASA Ozone Watch. Moderate ozone losses (orange) are visible amid widespread areas of more potent ozone losses (red).
'Modest Ozone Hole'
Paul Newman, head of NASA's ozone research team and chief scientist for Earth sciences at NASA's Goddard Space Flight Center, said: "It's a very modest ozone hole."
He attributed this to diminishing levels of human-generated chlorine compounds, coupled with favorable Antarctic stratospheric weather that slightly ameliorated ozone levels this year.
It is worth noting that the ozone layer functions as Earth's natural shield against the Sun's harmful ultraviolet radiation. A thinning ozone layer implies reduced defense against UV rays, potentially leading to sunburns, cataracts, and skin cancer in humans.
Each September, the ozone layer depletes, forming an "ozone hole" over the Antarctic region. This term, however, does not denote a complete void of ozone but rather the area where ozone concentrations plummet below the historical threshold of 220 Dobson Units.
The onset of ozone depletion was first reported in 1985, and levels have been closely monitored since 1979, according to NASA.
NASA noted that the Montreal Protocol of 1987, followed by subsequent amendments, prohibited the global production of CFCs and other ozone-depleting substances by 2010.
This concerted effort to curb emissions has resulted in a decline of ozone-destroying chemicals in the atmosphere and promising signs of stratospheric ozone recovery.
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NASA and NOAA Monitoring the Ozone Layer
NASA and NOAA employ various instruments aboard satellites like Aura, NOAA-NASA Suomi NPP, and NOAA-20 to monitor the ozone layer both over the pole and globally.
Additionally, Aura's Microwave Limb Sounder provides estimates of ozone-destroying chlorine. In-depth measurements are also taken to gauge the thickness of the ozone layer.
These include the release of weather balloons carrying ozonesondes and ground-based measurements employing a Dobson spectrophotometer conducted at NOAA's South Pole Baseline Atmospheric Observatory.
NOAA recorded a minimal value of 111 Dobson units (DU) over the South Pole on October 3, while NASA's measurements, averaged over a wider area, registered a low of 99 DUs on the same date.
To put this into perspective, in 1979, the average concentration above Antarctica was 225 DU. This year, approximately 95% depletion was observed, where total ozone loss within the stratosphere over the South Pole is typically close to 100%.
The eruption of the Hunga Tonga-Hunga Ha'apai volcano in January 2022 likely contributed to this year's ozone depletion, with the water vapor released potentially enhancing ozone-depletion reactions over the Antarctic early in the season, according to researchers.
While the eruption did impact the Antarctic stratosphere, quantifying its precise influence on the ozone hole remains an ongoing endeavor.
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