Dr Paul Newman, GSFC, NASA

will speak on

When will the Antarctic ozone hole recover?

Time: 2:15PM
Date: Thu 21st September 2006
Location: Mathematical Sciences Seminar Room [map]

Further information

Abstract: The Antarctic ozone hole develops each year and culminates by early spring
(late September - early October). Antarctic ozone values have been monitored since 1979
using satellite observations from the TOMS instrument. The severity of the hole has been
assessed from TOMS using the minimum total ozone value from the October monthly mean
(depth of the hole) and by calculating the average area coverage during this September
-October period. Ozone is mainly destroyed by halogen (chlorine and bromine) catalytic
cycles, and these losses are modulated by temperature variations in the collar of the
polar lower stratospheric vortex. In this talk, I will show the relationships of halogens
and temperature to both the size and depth of the hole. Because atmospheric halogen levels
are responding to international agreements that limit or phase out production, the amount
of halogens in the stratosphere should decrease over the next few decades. Using
projections of halogen levels combined with age-of-air estimates, we find that the ozone
hole is recovering at an extremely slow rate and that large ozone holes will regularly
recur over the next 2 decades. The ozone hole will begin to show first signs of recovery
in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070.
This 2070 recovery is 20 years later than recent projections. I will also discuss current
assessments of mid-latitude ozone recovery.

(This talk is part of the Meteorology series.)

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