Antarctic Ozone Hole Reaches 25 Million Square Kilometers Amid Accelerated Growth
- The Antarctic ozone hole reached an expanded area of 25 million square kilometers on September 12, according to data from the Copernicus Atmosphere Monitoring Service, outpacing historical averages...
- Persistent cold stratospheric temperatures and strong circumpolar winds, commonly referred to as the polar vortex, drove the formation of the large ozone depletion zone, according to NASA and...
- Ongoing reductions in ozone-depleting substances controlled under the Montreal Protocol prevented the ozone hole from growing even larger under identical weather conditions, according to agency researchers.
The Antarctic ozone hole reached an expanded area of 25 million square kilometers on September 12, according to data from the Copernicus Atmosphere Monitoring Service, outpacing historical averages for the period by roughly 5 million square kilometers. Early expansion of the seasonal thinning above the Southern Hemisphere coincided with a sharp temperature drop approximately 20 kilometers above the South Pole, according to measurements tracked by CAMS director Laurence Rouil. Separate observations from NASA and the National Oceanic and Atmospheric Administration recorded the annual Antarctic ozone hole reaching a peak size of 24.8 million square kilometers on September 20.
Atmospheric Conditions and Polar Vortex Dynamics
Persistent cold stratospheric temperatures and strong circumpolar winds, commonly referred to as the polar vortex, drove the formation of the large ozone depletion zone, according to NASA and NOAA scientists. These cold conditions enable the formation of polar stratospheric clouds during the austral spring spanning August through November. Chemical reactions occurring on the surfaces of these cloud particles activate halogens such as chlorine and bromine in the presence of sunlight, leading to the breakdown of ozone molecules. Weather balloon measurements from the South Pole revealed a nearly complete elimination of ozone inside a 4-mile-high column of the stratosphere. Despite the large spatial extent, CAMS diagnostics noted that the ozone column minimum values and overall ozone mass deficit remained close to historical averages.
Long-Term Recovery and Montreal Protocol Impact
Ongoing reductions in ozone-depleting substances controlled under the Montreal Protocol prevented the ozone hole from growing even larger under identical weather conditions, according to agency researchers. Paul A. Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center, stated that Antarctic stratosphere chlorine and bromine levels have declined about 16 percent from their peak in the year 2000. “We have a long way to go, but that improvement made a big difference this year. The hole would have been about a million square miles larger if there was still as much chlorine in the stratosphere as there was in 2000.” — Paul A.
Monitoring Instruments and Ongoing Tracking
Space agencies utilize a suite of instruments to monitor the development, peak, and breakup of the seasonal ozone hole. The Ozone Monitoring Instrument on NASA’s Aura satellite, alongside Ozone Mapping Profiler Suites on the Suomi National Polar-orbiting Partnership and NOAA-20 satellites, track atmospheric ozone levels from space. Additionally, the Aura satellite’s Microwave Limb Sounder measures chlorine-containing gases in the stratosphere, while NOAA teams release ozonesondes via weather balloons ascending up to 21 miles above the South Pole to measure vertical layer thickness.
