2012 Antarctic Ozone Hole Second Smallest in 20 Years

Oct. 24, 2012

Steve Cole
Headquarters, Washington
202-358-0918
stephen.e.cole@nasa.gov

Katy Human
NOAA Office of Communications and External Affairs, Boulder, Colo.
303-497-4747
katy.g.human@noaa.gov

RELEASE: 12-371

2012 ANTARCTIC OZONE HOLE SECOND SMALLEST IN 20 YEARS

WASHINGTON -- The average area covered by the Antarctic ozone hole
this year was the second smallest in the last 20 years, according to
data from NASA and National Oceanic and Atmospheric Administration
(NOAA) satellites. Scientists attribute the change to warmer
temperatures in the Antarctic lower stratosphere.

The ozone hole reached its maximum size Sept. 22, covering 8.2 million
square miles (21.2 million square kilometers), or the area of the
United States, Canada and Mexico combined. The average size of the
2012 ozone hole was 6.9 million square miles (17.9 million square
kilometers). The Sept. 6, 2000 ozone hole was the largest on record
at 11.5 million square miles (29.9 million square kilometers).

"The ozone hole mainly is caused by chlorine from human-produced
chemicals, and these chlorine levels are still sizable in the
Antarctic stratosphere," said NASA atmospheric scientist Paul Newman
of NASA's Goddard Space Flight Center in Greenbelt, Md. "Natural
fluctuations in weather patterns resulted in warmer stratospheric
temperatures this year. These temperatures led to a smaller ozone
hole."

The ozone layer acts as Earth's natural shield against ultraviolet
radiation, which can cause skin cancer. The ozone hole phenomenon
began making a yearly appearance in the early 1980s. The Antarctic
ozone layer likely will not return to its early 1980s state until
about 2065, Newman said. The lengthy recovery is because of the long
lifetimes of ozone-depleting substances in the atmosphere. Overall
atmospheric ozone no longer is declining as concentrations of
ozone-depleting substances decrease. The decrease is the result of an
international agreement regulating the production of certain
chemicals.

This year also showed a change in the concentration of ozone over the
Antarctic. The minimum value of total ozone in the ozone hole was the
second highest level in two decades. Total ozone, measured in Dobson
units (DU), reached 124 DU on Oct. 1. NOAA ground-based measurements
at the South Pole recorded 136 DU on Oct. 5. When the ozone hole is
not present, total ozone typically ranges from 240-500 DU.

This is the first year growth of the ozone hole has been observed by
an ozone-monitoring instrument on the Suomi National Polar-orbiting
Partnership (NPP) satellite. The instrument, called the Ozone Mapping
Profiler Suite (OMPS), is based on previous instruments, such as the
Total Ozone Mapping Spectrometer (TOMS) and the Solar Backscatter
Ultraviolet instrument (SBUV/2), which have flown on multiple
satellites. OMPS continues a satellite record dating back to the
early 1970s.

In addition to observing the annual formation and extent of the ozone
hole, scientists hope OMPS will help them better understand ozone
destruction in the middle and upper stratosphere with its Nadir
Profiler. Ozone variations in the lower stratosphere will be measured
with its Limb Profiler.

"OMPS Limb looks sideways, and it can measure ozone as a function of
height," said Pawan K. Bhartia, a NASA atmospheric physicist and OMPS
Limb instrument lead. "This OMPS instrument allows us to more closely
see the vertical development of Antarctic ozone depletion in the
lower stratosphere where the ozone hole occurs."

NASA and NOAA have been monitoring the ozone layer on the ground and
with a variety of instruments on satellites and balloons since the
1970s. Long-term ozone monitoring instruments have included TOMS,
SBUV/2, Stratospheric Aerosol and Gas Experiment series of
instruments, the Microwave Limb Sounder, the Ozone Monitoring
Instrument, and the OMPS instrument on Suomi NPP. Suomi NPP is a
bridging mission leading to the next-generation polar-orbiting
environmental satellites called the Joint Polar Satellite System,
will extend ozone monitoring into the 2030s.

NASA and NOAA have a mandate under the Clean Air Act to monitor
ozone-depleting gases and stratospheric depletion of ozone. NOAA
complies with this mandate by monitoring ozone via ground and
satellite measurements. The NOAA Earth System Research Laboratory in
Boulder, Colo., performs the ground-based monitoring. The Climate
Prediction Center performs the satellite monitoring.

To monitor the state of the ozone layer above Antarctica, visit:

http://ozonewatch.gsfc.nasa.gov


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