'Record breaking' Antarctic ozone hole
Blue and purple areas show the least amount of ozone
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Friday, 20, Oct 2006 03:39
The Antarctic ozone hole has broken two records this year for the size of its area and depth, scientists have revealed.
Concerns over the size of the hole are high in that ozone plays a vital role in blocking harmful ultraviolet rays from the sun.
The hole is primarily caused by human-produced compounds which release chlorine and bromine gases in the stratosphere.
Ozone monitoring instruments on Nasa's aura satellite measure the total amount of ozone from the ground to the upper atmosphere over the entire Antarctic continent.
"From September 21st to 30th, 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 centre.
Measurements taken in October also found that nearly all of the ozone in the layer between eight and 13 miles above the Earth's surface had been destroyed.
David Hofmann, director of the global monitoring division at the NOAA Earth system research laboratory, commented: "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."
Part of the reason behind the extent of the ozone hole is colder than average temperatures. Warmer temperatures lead to smaller holes, while colder ones cause deeper and larger holes.
Scientists have estimated that the hole will decrease in area by about 0.1 to 0.2 per cent for the next five to ten years. However, this decrease is marked each year by large variations caused by weather fluctuations.
According to the United Nations the ozone hole will fully recovery by 2065.