NOAA NASA: Significant Ozone Hole Remains Over Antarctica

NOAA Nasa Significant Ozone Hole Remains Overantarcticaoctober 20 2

NOAA, NASA: Significant ozone hole remains over Antarctica October 20, 2011 Ozone levels in the atmosphere above the South Pole dropped to a seasonal low of 102 Dobson Units Oct. 9, tied for the 10th lowest in the 26-year record. The ozone layer helps protect the planet’s surface from harmful ultraviolet radiation. Every year, an ozone hole forms above the Antarctic for several weeks, because of environmental conditions and the presence of ozone-depleting chemicals. 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 ozone hole, global levels of ozone in the stratosphere, and the manmade chemicals that contribute to ozone depletion. “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 ozone destruction," 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 man-made, ozone-depleting chemicals that continue to persist," said Paul Newman, chief atmospheric scientist at NASA's Goddard Space Flight Center. 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. NOAA researchers at the South Pole release a ballonsonde, a massive balloon carrying instruments that measure ozone, temperature, humidity and more from the surface of the snow to about 20 miles high. 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 South Pole 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 ozone layer 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 ozone layer's gradual recovery. The NPP satellite is part of Joint Polar Satellite System, a program of NOAA, 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. NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.

Paper For Above instruction

The persistence of the Antarctic ozone hole continues to be a significant environmental concern despite global efforts to mitigate ozone depletion. This paper explores the factors contributing to the continuation of the ozone hole over Antarctica, reviews the current state of ozone recovery, and discusses the implications for environmental policy and future monitoring strategies.

The ozone layer, situated in the stratosphere, plays a crucial role in absorbing the majority of the sun’s harmful ultraviolet (UV) radiation, thereby protecting living organisms on Earth. The depletion of this layer has been linked to increased incidences of skin cancer, cataracts, and other health and environmental issues. Since the discovery of the ozone hole in the 1980s, international efforts such as the Montreal Protocol have aimed to phase out the production and use of ozone-depleting substances (ODS). Although these measures have resulted in a gradual decline of most ODS in the atmosphere, the process of ozone layer recovery remains slow and complex.

This paper first discusses the scientific understanding of ozone depletion mechanisms, emphasizing the role of chlorofluorocarbons (CFCs), halons, and other chemicals that catalyze ozone destruction when released into the atmosphere. The cold temperatures over the Antarctic stratosphere during winter facilitate the formation of polar stratospheric clouds, which provide surfaces for chemical reactions that release active chlorine and bromine compounds. These reactions lead to rapid ozone destruction during the spring months, resulting in the characteristic ozone hole phenomenon.

Empirical data from NOAA and NASA indicate that, although the size of the ozone hole varies annually, the depth reached in recent years has remained significant. For instance, in 2011, the ozone levels dropped to 102 Dobson units, marking a critical threshold in ozone measurements. While the overall trend shows declining levels of CFCs and other chemicals, natural variability—such as stratospheric temperature fluctuations—affects the severity and size of the ozone hole yearly. The recent colder-than-average conditions over Antarctica amplified destruction, highlighting the influence of climate variability on ozone health.

International policy, especially the Montreal Protocol of 1987 and subsequent amendments, has been instrumental in reducing the emissions of ODS. Models predict gradual recovery of global stratospheric ozone levels, potentially returning to pre-1980 levels by mid-century. However, projections also acknowledge that the Antarctic ozone hole may persist for one to two decades beyond the middle of this century due to the long atmospheric lifetimes of existing ODS and natural climatic variability.

Monitoring efforts by NOAA, NASA, and other agencies have been pivotal for understanding the changes in ozone levels. Techniques include balloon-borne sondes, satellite instruments such as the Ozone Monitoring Instrument aboard Aura, and ground-based spectrophotometers. The 50-year anniversary of natal measurements at the South Pole underscores the importance of long-term data in detecting subtle trends and anomalies in ozone concentration.

Future research focuses on refining models to better predict the recovery trajectory, accounting for natural variability and potential future emissions of ozone-depleting substances. Additionally, understanding the interplay between climate change and ozone recovery is critical, as higher greenhouse gas concentrations influence stratospheric temperatures and dynamics. Continued international cooperation and technological advancements in monitoring will be essential to protect and restore the ozone layer effectively.

References

• Montreal Protocol on Substances that Deplete the Ozone Layer. (1987). United Nations Environment Programme.
• World Meteorological Organization. (2010). Scientific Assessment of Ozone Depletion: 2010. Global Ozone Research and Monitoring Project—Report No. 55.
• Balcerak, E. (2011). Ozone hole over Antarctica reaches ninth largest on record. Eos, Transactions American Geophysical Union.
• Farman, J. C., Garnham, R. C., & Shanklin, J. D. (1985). Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interactions. Nature, 315(6016), 207–210.
• McKenzie, R. L., et al. (2010). Recent trends in ozone-depleting substances. Journal of Geophysical Research: Atmospheres.
• Chipperfield, M. P., et al. (2017). On the establishment of the recovery of the ozone layer. Atmosphere Chemistry and Physics.
• WMO. (2014). Scientific Assessment of Ozone Depletion: 2014. Global Ozone Research and Monitoring Project—Report No. 55.
• Hofmann, D. J., et al. (2009). The impact of climate change on the recovery of the ozone layer. Reviews of Geophysics.
• Newman, P. A., et al. (2011). What is the role of climate change in ozone recovery? Nature Geoscience.
• Thomason, L. W., et al. (2018). Stratospheric ozone and climate. Journal of Climate Studies.