This year's ozone hole over the southern hemisphere is again deep and larger-than-average due to the colder than usual winter atmosphere over the region. It reached its maximum area on October 7 and ranked as the 13th largest since 1979, according to NASA and NOAA.
NASA satellite observations determined the ozone hole in 2021 reached a maximum of 24.8 million square kilometers (9.6 million square miles), before beginning to shrink in mid-October.1
On October 7, NOAA scientists recorded a total-column ozone concentration of 102 Dobson units, the 8th-lowest level since 1986. Prior to the emergence of the ozone hole in the 1970s, average ozone above the South Pole in September and October ranged from 250 to 350 Dobson units.
At altitudes between 14 and 21 km (8 and 13 miles) ozone was nearly completely absent during the ozone hole’s maximum.
False-color view of total ozone over the Antarctic pole on October 7, 2021. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone. Credit: NASA/GSFC, OzoneWatch
Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere).2
Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation. In the lower atmosphere (the troposphere) near the Earth’s surface, ozone is created by chemical reactions between air pollutants from vehicle exhaust, gasoline vapors, and other emissions. At ground level, high concentrations of ozone are toxic to people and plants.
1 Substantial Antarctic ozone hole in 2021 – EO
2 NASA Ozone Watch – GSFC
Featured image credit: NASA/GSFC, OzoneWatch
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