Antarctic Ozone Hole Expected To Last Longer This Year

TERRADAILY

More images and data at NASA's Earth Observatory

Auckland - Oct 2001
The Antarctic ozone hole has formed again this year, as expected, but it hasn't matched the records set last year.

"It reached a maximum size of just over 26 million square kilometres in mid-September, and it still occupies more than 20 million square kilometres", said Dr Stephen Wood, a NIWA scientist currently at Scott Base, New Zealand's Antarctic research station. "Last year the hole reached 30 million square kilometres in area, and the minimum ozone reading was 126 Dobson Units at Scott Base, whereas this year's minimum was 132 Units."

However, this year's hole looks set to stay around longer. Last year the hole formed early and broke up early. This time last year it was already 5 million square kilometres smaller than the hole is now.

The ozone holes that form each springtime over Antarctica are triggered by a combination of chlorine pollutants in the atmosphere, extremely cold winter temperatures, and the return of sunlight in spring. The polar vortex, a band of strong winds that effectively keeps the atmosphere above Antarctica isolated during winter, is a key part of the recipe. Large year-to-year variations in the severity of the ozone hole can be caused by differences in the polar vortex.

Last year, features of the vortex contributed to an early formation of the ozone hole and a very early break up. This year the vortex and the hole appear to be much more stable and circular, which suggests that the hole will probably last longer -- into November and possibly even into December.

"The longer the ozone hole persists, the more likely it is that ozone- depleted air from the dispersing hole will reach New Zealand when the sun is high in the sky, increasing the risk of occurrence of periods with high ultraviolet radiation", said Dr Wood.

Despite the record ozone loss over Antarctica in 2000, the impact on New Zealand was less severe than in 1998, because last year the hole broke up at the end of November. In 1998, the hole broke up around Christmas, when the sun is highest in the sky and UV penetration is greatest and large numbers of New Zealanders are enjoying the outdoors. NIWA actively monitors UV levels and provides regular public updates.

As well as the short-term impact of high UV radiation for a few days, there is another part to this Antarctic ozone hole phenomenon.

"When the ozone hole breaks up, it reduces ozone levels throughout the Southern Hemisphere. This dilution accounts for about half of the 15% increase in peak summertime UV levels that have occurred in the last 20 years over New Zealand."

The Antarctic ozone holes will be with us for several decades to come. If current models are correct, the ozone holes are now at their most severe. Climate change could delay the recovery in ozone levels by some years. Measures to reduce the levels of chlorine pollutants are starting to take effect, but it could be 50 years before ozone levels are restored.

TERRADAILY

2001 Ozone Hole About The Same Size As Past Three Years

Washington - Oct 17, 2001
Satellite data show the area of this year's Antarctic ozone hole peaked at about 26 million square kilometers -- roughly the size of North America -- making the hole similar in size to those of the past three years, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). Researchers have observed a leveling-off of the hole size and predict a slow recovery.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.