WASHINGTON -- The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on Sept. 12. It stretched to 10.05 million square miles, the ninth largest ozone hole on record. Above the South Pole, the ozone hole reached its deepest point of the season on Oct. 9, tying this year for the 10th lowest in this 26-year record.
NASA and the National Oceanic and Atmospheric Administration (NOAA) use balloon-borne instruments, ground-based instruments and satellites to monitor the annual Antarctic ozone hole, global levels of ozone in the stratosphere and the manmade chemicals that contribute to ozone depletion.
"The colder than average temperatures in the stratosphere this year caused a larger than average ozone hole," said Paul Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Md. "Even though it was relatively large, the area of this year's ozone hole was within the range we'd expect given the levels of manmade ozone-depleting chemicals that continue to persist in the atmosphere."
The ozone layer helps protect the planet's surface from harmful ultraviolet radiation. Ozone depletion results in more incoming radiation that can hit the surface, elevating the risk of skin cancer and other harmful effects.
"The manmade chemicals known to destroy ozone are slowly declining because of international action, but there are still large amounts of these chemicals doing damage," said James Butler, director of NOAA's Global Monitoring Division in Boulder, Colo.
In the Antarctic spring (August and September) the sun begins rising again after several months of darkness and polar-circling winds keep cold air trapped above the continent. Sunlight-sparked reactions involving ice clouds and manmade chemicals begin eating away at the ozone. Most years, the conditions for ozone depletion ease before early December when the seasonal hole closes.
|Contact: Steve Cole|
NASA/Goddard Space Flight Center