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15 Is there an ozone hole in the arctic?




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This article is from the Ozone Depletion: The Antarctic Ozone Hole FAQ, by Robert Parson rparson@spot.colorado.edu with numerous contributions by others.

15 Is there an ozone hole in the arctic?

There is no _massive_ ozone loss in the arctic, although there _is_
unusually large springtime ozone depletion, so the word "hole" is
not appropriate. I like the expression "arctic ozone dimple" but
this is not canonical :-). The arctic polar vortex is much weaker
than the antarctic, arctic temperatures are several degrees higher,
and polar stratospheric clouds are less common and tend to break
up earlier in the spring.) [Salby and Garcia] Thus even though
wintertime ClO gets very high, as high as antarctic ClO in 1991-2, it
does not remain high through the spring, when it counts. [AASE]

Recent UARS measurements, however, indicate that in 1993 arctic
stratosphere temperatures stayed low enough to retain PSC's until
late February, and ClO remained high into March. Large ozone
depletions, ~10-20%, were reported for high latitudes in the
Northern Hemisphere; these still do not qualify as an "ozone hole"
but they do seem to indicate that the same physics and chemistry
are operating, albeit with much less efficiency. [Waters et al.]
[Gleason et al.] Large ozone depletion was not seen in the spring of
1994, but appeared again in the spring of 1995 [Wirth and Renger 1996],
and, according to preliminary reports, again in 1996 (WMO press
release, 12 March 1996, http://www.wmo.ch/web/Press/Press586.html).

If "global warming" does indeed take place during the first
few decades of the next century, we may see a dramatic change in
arctic ozone. The greenhouse effect warms the surface of the
earth, but at the same time _cools_ the stratosphere. Since there
is much less air in the stratosphere, 2-3 degrees of surface
warming corresponds to a much larger decrease in stratospheric
temperatures, as much as 10 degrees. This could lead to a true
ozone hole in the arctic, although it would still probably be
smaller and weaker than the antarctic hole. [Austin et al.]

The 27 August issue of _Science_ magazine contains 8 papers devoted
to arctic ozone depletion in the winter of 1991-92. [AASE] See also
[von der Gathen et al. 1995], [Manney et al. 1994], and [Wirth
and Renger 1996] who present evidence linking arctic ozone depletion
to chlorine and bromine chemistry.

 

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