Ozone Levels Over Antarctica
Down 30 Percent Says UN
By Stephanie Nebehay

GENEVA (Reuters) - Satellite data from above Antarctica show an unusually early and severe drop in the level of ozone, the World Meteorological Organization said on Tuesday.
The United Nations agency said an average drop of 30 percent was recorded compared to the benchmark 1964-76 period, before a hole in the protective ozone layer was reported.
But it said meteorological conditions in the stratosphere could change and it was too soon to say if there would be record depletion of the layer this year.
The ozone protects people, animals, and crops from the sun's dangerous ultraviolet rays.
Chlorofluorocarbons (CFCs) and other ozone-destroying chemicals have been banned since 1996, but scientists say it will be decades before the ozone layer recovers.
Ozone depletion normally begins in late August, intensifying until it peaks in October, and eventually recovers in November or early December.
``The latest satellite observations in the sunlit portion of the Antarctica perimeter show an average decrease of about 30 percent in the total amount of ozone overhead when compared to the 1964-76 norms,'' WMO said in a statement.
``This is double the 15 percent reported two weeks ago and unusual for this early period.
``The sunlit region surrounding Antarctica continues to have considerably less ozone than normal and has been demonstrated with both ground-based and satellite measurements,'' it added.
Substantial Decreases
Preliminary ground-based measurements taken between August 16-22 from four Antarctic stations all showed ``substantial decreases'' when compared to the period before the ozone hole appeared.
France's Dumont d'Urville reported levels 20 percent below, Russia's Mirny reported 35 percent below, Japan's Syowa and Ukraine's Vernadsky reported 25 percent below, it said.
``Both Syowa and Vernadsky have ozone records extending back more than 25 years that indicate the Syowa weekly average is the second lowest on record while for Vernadsky this year is the lowest,'' the statement said.
``However, prevailing meteorological conditions in the stratosphere, particularly during the Austral Spring, strongly influence the extent and intensity of ozone loss and may substantially reduce the total seasonal depletion.''
Michael Proffitt, WMO's senior scientific officer and ozone expert, told Reuters: ``These conditions are a bit unusual, they are strong initial conditions. It is a strong start.
``Any year could be a record year... We are watching carefully and will have a much better idea in two weeks,'' the American expert added.
Sunlight should reach the South Pole around September 21-22, enabling scientists to make further measurements, according to Proffitt. ``We expect to see significant loss as it becomes uncovered,'' he said.
Ground-based measurements first detected the ozone hole over Antarctica in about 1985, according to Proffitt, who took part in a NASA project two years later which flew experts in and out of the hole as it developed.
``Things can change. The wonderful thing about nature is we can get meteorological conditions that can change the picture,'' he said.

This Site Served by TheHostPros