Featured Research

from universities, journals, and other organizations

2008 Sees Fifth Largest Ozone Hole

Date:
November 6, 2008
Source:
National Oceanic And Atmospheric Administration
Summary:
The ozone hole over Antarctica, which fluctuates in response to temperature and sunlight, grew to the size of North America in a one-day maximum in September that was the fifth largest on record, since NOAA satellite records began in 1979.

The ozone hole over Antarctica, which fluctuates in response to temperature and sunlight, grew to the size of North America in a one-day maximum in September that was the fifth largest on record, since NOAA satellite records began in 1979.
Credit: NOAA

The ozone hole over Antarctica, which fluctuates in response to temperature and sunlight, grew to the size of North America in a one-day maximum in September that was the fifth largest on record, since NOAA satellite records began in 1979.

The Antarctic ozone hole reached its annual maximum on Sept. 12, 2008, stretching over 27 million kilometers, or 10.5 square miles. The area of the ozone hole is calculated as an average of the daily areas for Sept. 21-30 from observations from the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite.

NOAA scientists, who have monitored the ozone layer since 1962, have determined that this year’s ozone hole has passed its seasonal peak for 2008. Data is available at online.

The primary cause of the ozone hole is human-produced compounds called chlorofluorocarbons, or CFCs, which release ozone-destroying chlorine and bromine into the atmosphere. Earth’s protective ozone layer acts like a giant umbrella, blocking the sun’s ultraviolet-B rays. Though banned for the past 21 years to reduce their harmful build up, CFCs still take many decades to dissipate from the atmosphere.

According to NOAA scientists, colder than average temperatures in the stratosphere may have helped play a part in allowing the ozone hole to develop more fully this year.

“Weather is the most important factor in the fluctuation of the size of the ozone hole from year-to-year,” said Bryan Johnson, a scientist at NOAA’s Earth System Research Laboratory in Boulder, which monitors ozone, ozone-depleting chemicals, and greenhouse gases around the globe. “How cold the stratosphere is and what the winds do determine how powerfully the chemicals can perform their dirty work.”

NASA satellites measured the maximum area of this year’s ozone hole at 10.5 million square miles and four miles deep, on Sept. 12. Balloon-borne sensors released from NOAA’s South Pole site showed the total column of atmospheric ozone dropped to its lowest count of 107 Dobson units on Sept. 28. Dobson units are a measure of total ozone in a vertical column of air.

In 2006, record-breaking ozone loss occurred as ozone thickness plunged to 93 Dobson units on Oct. 9 and sprawled over 11.4 million square miles at its peak. Scientists blamed colder-than-usual temperatures in the stratosphere for its unusually large size. Last year’s ozone hole was average in size and depth.

Starting in May, as Antarctica moves into a period of 24-hour-a-day darkness, rotating winds the size of the continent create a vortex of cold, stable air centered near the South Pole that isolates CFCs over the continent. When spring sunshine returns in August, the sun’s ultraviolet light sets off a series of chemical reactions inside the vortex that consume the ozone. The colder and more isolated the air inside the vortex, the more destructive the chemistry. By late December the southern summer is in full swing, the vortex has crumbled, and the ozone has returned—until the process begins anew the following winter.

The 1987 Montreal Protocol and other regulations banning CFCs reversed the buildup of chlorine and bromine, first noticed in the 1980s.

“These chemicals—and signs of their reduction—take several years to rise from the lower atmosphere into the stratosphere and then migrate to the poles,” said NOAA’s Craig Long, a research meteorologist at NOAA’s National Centers for Environmental Prediction. “The chemicals also typically last 40 to 100 years in the atmosphere. For these reasons, stratospheric CFC levels have dropped only a few percent below their peak in the early 2000s.“

“The decline of these harmful substances to their pre-ozone hole levels in the Antarctic stratosphere will take decades,” said NOAA atmospheric chemist Stephen Montzka of the Earth System Research Laboratory. “We don’t expect a full recovery of Antarctic ozone until the second half of the century.”


Story Source:

The above story is based on materials provided by National Oceanic And Atmospheric Administration. Note: Materials may be edited for content and length.


Cite This Page:

National Oceanic And Atmospheric Administration. "2008 Sees Fifth Largest Ozone Hole." ScienceDaily. ScienceDaily, 6 November 2008. <www.sciencedaily.com/releases/2008/11/081105175154.htm>.
National Oceanic And Atmospheric Administration. (2008, November 6). 2008 Sees Fifth Largest Ozone Hole. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2008/11/081105175154.htm
National Oceanic And Atmospheric Administration. "2008 Sees Fifth Largest Ozone Hole." ScienceDaily. www.sciencedaily.com/releases/2008/11/081105175154.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins