Elvia Thompson
Headquarters, Washington       September 30, 2002
(Phone: 202/358-1696)

Robert J. Gutro/Cynthia M. O'Carroll
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-4044 / 614-5563)

Carmeyia Gillis 
National Oceanic and Atmospheric Administration/NOAA Climate 
Prediction Center
(Phone: 301/763-8000, ext. 7163)

RELEASE: 02-185

UNUSUALLY SMALL ANTARCTIC OZONE HOLE THIS YEAR 
ATTRIBUTED TO EXCEPTIONALLY STRONG STRATOSPHERIC WEATHER 
SYSTEMS

     Scientists from NASA and the Commerce Department's 
National Oceanic and Atmospheric Administration (NOAA) have 
confirmed the ozone hole over the Antarctic this September is 
not only much smaller than it was in 2000 and 2001, but has 
split into two separate "holes." 

The researchers stressed the smaller hole is due to this 
year's peculiar stratospheric weather patterns and that a 
single year's unusual pattern does not make a long-term 
trend. Moreover, they said, the data are not conclusive that 
the ozone layer is recovering.

Paul Newman, a lead ozone researcher at NASA's Goddard Space 
Flight Center, Greenbelt, Md., said this year, warmer-than-
normal temperatures around the edge of the polar vortex that 
forms annually in the stratosphere over Antarctica are 
responsible for the smaller ozone loss.

Estimates for the last two weeks of the size of the Antarctic 
Ozone Hole (the region with total column ozone below 220 
Dobson Units), from the NASA Earth Probe Total Ozone Mapping 
Spectrometer (EPTOMS) and the NOAA-16 Solar Backscatter 
Ultraviolet instrument (SBUV/2), are around 15 million square 
kilometers (6 million square miles). These values are well 
below the more-than 24 million sq. km. (9 million sq. mi.) 
seen the last six years for the same time of year.

The stratosphere is a portion of the atmosphere about 6-to-30 
miles above the Earth's surface where the ozone layer is 
found. The ozone layer prevents the sun's harmful ultraviolet 
radiation from reaching the Earth's surface. Ultraviolet 
radiation is a primary cause of skin cancer. Without 
protective upper-level ozone, there would be no life on 
Earth.

"The Southern Hemisphere's stratosphere was unusually 
disturbed this year," said Craig Long, meteorologist at 
NOAA's Climate Prediction Center (CPC). The unusual weather 
patterns were so strong, the ozone hole split into two pieces 
during late September. NOAA's CPC has been monitoring and 
studying the ozone since the early 1970s. "This is the first 
time we've seen the polar vortex split in September," said 
Long. 

At South Pole Station, balloon-borne ozone-measuring 
instruments launched by NOAA's Climate Monitoring and 
Diagnostics Laboratory (CMDL) reveal the vertical structure 
of the developing ozone hole. Bryan Johnson, a scientist with 
CMDL, said the main ozone depletion region, from 7-to-14 
miles above the Earth, has large ozone losses, similar to the 
last few years. At more than 15 miles above the Earth, 
surface measurements show higher-than-normal ozone 
concentrations and higher temperatures. 

The combination of these layers indicate total ozone levels 
in a column of atmosphere will be higher than observed during 
the last few years, Johnson said. However, some layers may 
still show complete ozone destruction by early October, when 
ozone depletion is greatest.

In 2001, the Antarctic ozone hole was larger than the 
combined area of the United States, Canada and Mexico. The 
last time the ozone hole was this small was in 1988, and that 
was also due to warm atmospheric temperatures.

"While chlorine and bromine chemicals cause the ozone hole, 
temperature is also a key factor in ozone loss," Newman said. 
The Montreal Protocol and its amendments banned chlorine-
containing chlorofluorocarbons (CFCs) and bromine-containing 
halons in 1995, because of their destructive effect on the 
ozone layer. However, CFCs and halons are extremely long-
lived and still linger at high concentrations in the 
atmosphere.

The coldest temperatures over the South Pole typically occur 
in August and September. Thin clouds form in these cold 
conditions, and chemical reactions on the cloud particles 
help chlorine and bromine gases to rapidly destroy ozone. By 
early October, temperatures usually begin to warm, and 
thereafter the ozone layer starts to recover.

NOAA and NASA continuously observe Antarctic ozone with a 
combination of ground, balloon, and satellite-based 
instruments. 

For more information and images see:
http://www.gsfc.nasa.gov/topstory/20020926ozonehole.html
http://toms.gsfc.nasa.gov/ozone/today.html
http://www.cpc.ncep.noaa.gov/products/stratosphere/polar/pola
r.html
http://www.cmdl.noaa.gov/
http://toms.gsfc.nasa.gov/eptoms/dataqual/ozone.html
http://www.cpc.ncep.noaa.gov/products/stratosphere/polar/gif_
files/ozone_hole_plot.png

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