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.

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