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antarctic ozone hole - oh dear


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Posted
  • Location: Brecon Beacons, South Wales
  • Location: Brecon Beacons, South Wales

    Oct. 19, 2006

    Erica Hupp/Dwayne Brown

    Headquarters, Washington

    202-358-1237/1726

    Anatta

    NOAA, Earth System Research Laboratory, Boulder, Colo.

    303-497-6288

    RELEASE: 06-338

    NASA AND NOAA ANNOUNCE ANTARCTIC OZONE HOLE IS A RECORD BREAKER

    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.

    The ozone layer acts to protect life on Earth by blocking harmful

    ultraviolet rays from the sun. The "ozone hole" is a severe depletion

    of the ozone layer high above Antarctica. It is primarily caused by

    human-produced compounds that release chlorine and bromine gases in

    the stratosphere.

    "From September 21 to 30, the average area of the ozone hole was the

    largest ever observed, at 10.6 million square miles," said Paul

    Newman, atmospheric scientist at NASA's Goddard Space Flight Center,

    Greenbelt, Md. If the stratospheric weather conditions had been

    normal, the ozone hole would be expected to reach a size of about 8.9

    to 9.3 million square miles, about the surface area of North America.

    The Ozone Monitoring Instrument on NASA's Aura satellite measures the

    total amount of ozone from the ground to the upper atmosphere over

    the entire Antarctic continent. This instrument observed a low value

    of 85 Dobson Units (DU) on Oct. 8, in a region over the East

    Antarctic ice sheet. Dobson Units are a measure of ozone amounts

    above a fixed point in the atmosphere. The Ozone Monitoring

    Instrument was developed by the Netherlands' Agency for Aerospace

    Programs, Delft, The Netherlands, and the Finnish Meteorological

    Institute, Helsinki, Finland.

    Scientists from NOAA's Earth System Research Laboratory in Boulder,

    Colo., use balloon-borne instruments to measure ozone directly over

    the South Pole. By Oct. 9, the total column ozone had plunged to 93

    DU from approximately 300 DU in mid-July. More importantly, nearly

    all of the ozone in the layer between eight and 13 miles above the

    Earth's surface had been destroyed. In this critical layer, the

    instrument measured a record low of only 1.2 DU., having rapidly

    plunged from an average non-hole reading of 125 DU in July and

    August.

    "These numbers mean the ozone is virtually gone in this layer of the

    atmosphere," said David Hofmann, director of the Global Monitoring

    Division at the NOAA Earth System Research Laboratory. "The depleted

    layer has an unusual vertical extent this year, so it appears that

    the 2006 ozone hole will go down as a record-setter."

    Observations by Aura's Microwave Limb Sounder show extremely high

    levels of ozone destroying chlorine chemicals in the lower

    stratosphere (approximately 12.4 miles high). These high chlorine

    values covered the entire Antarctic region in mid to late September.

    The high chlorine levels were accompanied by extremely low values of

    ozone.

    The temperature of the Antarctic stratosphere causes the severity of

    the ozone hole to vary from year to year. Colder than average

    temperatures result in larger and deeper ozone holes, while warmer

    temperatures lead to smaller ones. The NOAA National Centers for

    Environmental Prediction (NCEP) provided analyses of satellite and

    balloon stratospheric temperature observations. The temperature

    readings from NOAA satellites and balloons during late-September 2006

    showed the lower stratosphere at the rim of Antarctica was

    approximately nine degrees Fahrenheit colder than average, increasing

    the size of this year's ozone hole by 1.2 to 1.5 million square

    miles.

    The Antarctic stratosphere warms by the return of sunlight at the end

    of the polar winter and by large-scale weather systems

    (planetary-scale waves) that form in the troposphere and move upward

    into the stratosphere. During the 2006 Antarctic winter and spring,

    these planetary-scale wave systems were relatively weak, causing the

    stratosphere to be colder than average.

    As a result of the Montreal Protocol and its amendments, the

    concentrations of ozone-depleting substances in the lower atmosphere

    (troposphere) peaked around 1995 and are decreasing in both the

    troposphere and stratosphere. It is estimated these gases reached

    peak levels in the Antarctica stratosphere in 2001. However, these

    ozone-depleting substances typically have very long lifetimes in the

    atmosphere (more than 40 years).

    As a result of this slow decline, the ozone hole is estimated to

    annually very slowly decrease in area by about 0.1 to 0.2 percent for

    the next five to 10 years. This slow decrease is masked by large

    year-to-year variations caused by Antarctic stratosphere weather

    fluctuations.

    The recently completed 2006 World Meteorological Organization/United

    Nations Environment Programme Scientific Assessment of Ozone

    Depletion concluded the ozone hole recovery would be masked by annual

    variability for the near future and the ozone hole would fully

    recover in approximately 2065.

    "We now have the largest ozone hole on record," said Craig Long of

    NCEP. As the sun rises higher in the sky during October and November,

    this unusually large and persistent area may allow much more

    ultraviolet light than usual to reach Earth's surface in the southern

    latitudes.

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    Posted
  • Location: Berlin, Germany
  • Weather Preferences: Ample sunshine; Hot weather; Mixed winters with cold and mild spells
  • Location: Berlin, Germany

    Think they already have- CFC's banned globally (I think). Problem is, there's lots of old fridges, etc still with CFC's in them and with the slow destruction of ozone killing compounds it'll take ages to heal.

    Good job the hole isn't over the arctic. We'd have a lot more skin cancer cases.

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