The Ozone Layer is the name given to naturally occurring high concentrations of ozone located high up in the stratosphere between 35,000 – 160,000 feet.  The ozone layer is important to life on Earth because of its ability to filter out harmful doses of ultraviolet light from the Sun that has the ability to damage DNA in plants and animals and is the main cause of skin cancer in humans.  In this way, the ozone layer protects the Earth as a natural, global sunscreen.  In the early 1980’s scientists began to realize the ozone layer was thinning dramatically over the South Pole each spring.  This large, thin spot in the ozone layer came to be known as the “Ozone Hole.”  Throughout the 1980’s the thinning became dramatically worse and scientists connected the destruction to man-made chlorofluorocarbons (CFC’s) used in refrigeration and aerosol cans.  These chemicals stay in our atmosphere for a very long time so it was important to take action quickly.  In 1987 scientists, politicians, and world leaders were able to work together to sign the Montreal Protocol on Substances that Deplete the Ozone Layer and phase out worldwide production of these highly useful but environmentally harmful chemicals.  Since 1986, NOAA scientists have performed regular launches of high altitude balloons with instruments to measure the destruction, and recovery, of the ozone layer above the South Pole.

As summer comes to an end in the northern hemisphere, the sun is only beginning to return to the skies above Antarctica.  Throughout the long, dark winter, unique ice crystals formed in the unusually cold temperatures inside the “Polar Vortex.”  These ice crystals are known as Polar Stratospheric Clouds, or PSCs, and they allow the release of enormous amounts of destructive chlorine directly in to the protective ozone layer.  With the added energy of the rising sun, this free chlorine devastates the ozone layer and forms the now-annual Ozone Hole.

Every spring an ozone hole forms over Antarctica. Instruments flown on balloons launched year round from the South Pole Station measure ozone and temperature from the surface to a height of about 100,000 feet. The left graph shows ozone destruction within the ozone layer occurring during sunrise and the beginning of spring. The breakup of the ozone hole is shown when large amounts of ozone pour in at high altitudes and “fill in” the hole until the next year.

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