Significant ozone hole remains over Antarctica

Oct 20, 2011
This is a false-color view of total ozone over the Antarctic pole. 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/OMI

The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on September 12, stretching 10.05 million square miles, the ninth largest on record. Above the South Pole, the ozone hole reached its deepest point of the season on October 9 when total ozone readings dropped to 102 Dobson units, tied for the 10th lowest in the 26-year record.

The ozone layer helps protect the planet's surface from harmful ultraviolet radiation. NOAA and NASA use balloon-borne instruments, ground instruments, and satellites to monitor the annual South Pole , global levels of ozone in the stratosphere, and the manmade chemicals that contribute to .

"The upper part of the atmosphere over the South Pole was colder than average this season and that cold air is one of the key ingredients for ," said James Butler, director of NOAA's Global Monitoring Division in Boulder, Colo. Other key ingredients are ozone-depleting chemicals that remain in the atmosphere and ice crystals on which ozone-depleting chemical reactions take place.

"Even though it was relatively large, the size 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," said Paul Newman, chief at NASA's Goddard Space Flight Center.

This video is not supported by your browser at this time.
South Pole Ozone Animation. Credit: NOAA

Levels of most ozone-depleting chemicals are slowly declining due to international action, but many have long lifetimes, remaining in the atmosphere for decades. Scientists around the world are looking for evidence that the ozone layer is beginning to heal, but this year's data from Antarctica do not hint at a turnaround.

In August and September (spring in Antarctica), the sun begins rising again after several months of darkness. Circumpolar winds keep cold air trapped above the continent, and sunlight-sparked reactions involving ice clouds and manmade chemicals begin eating away at the ozone. Most years, the conditions for ozone depletion ease by early December, and the seasonal hole closes.

Levels of most ozone-depleting chemicals in the atmosphere have been gradually declining since an international treaty to protect the ozone layer, the 1987 Montreal Protocol, was signed. That international treaty caused the phase out of ozone-depleting chemicals, then used widely in refrigeration, as solvents and in aerosol spray cans.

Global atmospheric models predict that stratospheric ozone could recover by the middle of this century, but the ozone hole in the Antarctic will likely persist one to two decades beyond that, according to the latest analysis by the World Meteorological Organization, the 2010 Ozone Assessment, with co-authors from NOAA and NASA.

Researchers do not expect a smooth, steady recovery of Antarctic ozone, because of natural ups and downs in temperatures and other factors that affect depletion, noted NOAA ESRL scientist Bryan Johnson. Johnson helped co-author a recent NOAA paper that concluded it could take another decade to begin discerning changes in the rates of ozone depletion.

Johnson is part of the NOAA team tracks ozone depletion around the globe and at the South Pole with measurements made from the ground, in the atmosphere itself and by satellite. Johnson's "ozonesonde" group has been using balloons to loft instruments 18 miles into the atmosphere for 26 years to collect detailed profiles of ozone levels from the surface up. The team also measures ozone with satellite and ground-based instruments.

This November marks the 50th anniversary of the start of total ozone column measurements by the NOAA Dobson spectrophotometer instrument at station. Ground-based ozone column measurements started nearly two decades before the yearly Antarctic ozone hole began forming, therefore helping researchers to recognize this unusual change of the ozone layer.

NASA measures ozone in the stratosphere with the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. OMI continues a NASA legacy of monitoring the from space that dates back to 1972 and the launch of the Nimbus-4 satellite.

A new satellite scheduled to launch this month, the NPP satellite, features a new ozone-monitoring instrument, the Ozone Mapping and Profiler Suite, which will provide more detailed daily, global ozone measurements than ever before to continue the task of observing the layer's gradual recovery. The NPP satellite is part of Joint Polar Satellite System, a program of , NASA and the Department of Defense (formerly known as the NPOESS Preparatory Project). It is scheduled to launch October 27 from Vandenberg Air Force Base in California.

Explore further: NASA's HS3 looks Hurricane Edouard in the eye

Related Stories

AURA satellite peers into Earth's ozone hole

Dec 07, 2005

NASA researchers, using data from the agency's AURA satellite, determined the seasonal ozone hole that developed over Antarctica this year is smaller than in previous years.

Antarctic ozone - not a hole lot worse or better

Nov 10, 2005

The Antarctic ozone hole this year was the fourth largest to be recorded since measurements of ozone depletion began in 1979. CSIRO Marine and Atmospheric Research's expert in ozone depletion, Dr Paul Fraser, says while the ...

Study Finds Clock Ticking Slower On Ozone Hole Recovery

Jun 30, 2006

The Antarctic ozone hole's recovery is running late. According to a new NASA study, the full return of the protective ozone over the South Pole will take nearly 20 years longer than scientists previously expected.

NASA scientists reveal latest information on ozone hole

Sep 28, 2006

In 1987, the United States joined several other nations in signing the Montreal Protocol, an international treaty designed to protect the Earth's ozone layer by phasing out the production of a number of substances ...

Antarctic ozone hole is a double record breaker

Oct 19, 2006

NASA and National Oceanic and Atmospheric Administration (NOAA) scientists report this year's ozone hole in the polar region of the Southern Hemisphere has broken records for area and depth.

Recommended for you

Sculpting tropical peaks

5 hours ago

Tropical mountain ranges erode quickly, as heavy year-round rains feed raging rivers and trigger huge, fast-moving landslides. Rapid erosion produces rugged terrain, with steep rivers running through deep ...

Volcano expert comments on Japan eruption

6 hours ago

Loÿc Vanderkluysen, PhD, who recently joined Drexel as an assistant professor in Department of Biodiversity, Earth and Environmental Science in the College of Arts and Sciences, returned Friday from fieldwork ...

NASA's HS3 looks Hurricane Edouard in the eye

19 hours ago

NASA and NOAA scientists participating in NASA's Hurricane and Severe Storms Sentinel (HS3) mission used their expert skills, combined with a bit of serendipity on Sept. 17, 2014, to guide the remotely piloted ...

User comments : 0