Ozone data from Halley and Vernadsky/Faraday

The ozone hole is now an annual event which can be confidently
expected to recur each successive austral spring. The gases
responsible for ozone depletion will persist in the atmosphere for
such a long time that the situation will not improve significantly
until well into the next century.

It is now clear that ozone depletion by reactive halogen compounds
starts in midwinter at the sunlit edge of Antarctica. This has been
deduced from winter measurements of ozone by the Systhme d'Analyse des
Observations Zinithales (SAOZ) spectrometer at Vernadsky (Faraday)
incorporated into a chemical model of the stratosphere.

According to the model, the depletion covers much of a ring at the
vortex edge around Antarctica. The coherence of the ring suggests that
mixing between the edge of the vortex and the centre is weak. If this
is true, the ozone depletion near the edge of Antarctica is
independent of the depletion nearer the centre, and is limited by the
incidence of stratospheric clouds which convert unreactive chlorine
from CFCs to reactive forms. This contrasts with conditions in the
centre of Antarctica, where the colder temperatures mean that clouds
are ubiquitous, and so depletion is limited by the supply of
unreactive chlorine from aloft. If this occurs until late in the
spring, it is this ozone-poor air that often passes over populated
areas of South America. In the late spring, the Sun is high enough in
the sky for significant UV damage when this happens.

Recent evidence, based on models and satellite measurements, confirm
that the mixing is indeed weak until late in the spring. This is
particularly important when greenhouse gases are increasing, because
they will cool the stratosphere and increase the amount of
stratospheric cloud. The outcome of this serious. It is now evident
that the recovery of spring-time ozone depletion over the populated
regions of South America will be delayed beyond that expected from the
provisions of the Montreal Protocol.

A certain amount of ozone data are publicly available, in the form of
graphs and bulletins. These data have been collected from Halley and
Vernadsky (Faraday) stations since 1956 and were used for the 1985
Nature publication which identified stratospheric ozone depletion for
the first time.