Stolarski, R. S.

English

NASA Technical Reports Server

Nimbus 7 SBUV/TOMS Measurements of the Springtime
Antarctic Ozone Hole
R. S. Stolarski
NASA/Goddard Space Flight Center
Laboratory for Atmospheres
Greenbelt, MD 20771
The satellite data from the Nimbus 7 TOMS and SBUV instruments
significantly extend our view of the growing ozone minimum during the
South Polar spring and places constraints on possible mechanisms for
explaining the phenomenon. The deep minimum, or hole, has a structure
that looks much like the polar vortex. The areas of maximum decrease
are clearly confined spatially. There appears to be a smaller decrease
in the ozone maxima surrounding the polar region over the 7 years
studied. These are harder to interpret because of the strong planetary
waves in this region.
A most important mechanism constraint placed by this is that the
decrease takes place in September during twilight, not in the polar
night. During the period of polar night the parcels in the vortex are
not strictly confined to darkness but do spend a large fraction of their
time there with little exchange with air parcels outside the vortex.
The maximum rate of decrease occurs after most of the pole is sunlit.
The rate of falloff of the minimum values is about 0.6% per day extended
over 40-50 days in 1983.
Any explanation of the ozone change must be simultaneously consistent
with the year-to-year change as well as the rate of decrease through
September. These appear to be consistent with a chemical mechanism but
the problem is finding one which can affect ozone on such a short time
scale. The obvious chemicals are the halogens, bromine and chlorine.
Of these chlorine is the more likely because of the increase of its
concentration with time, although bromine may enhance the rate of ozone
loss in the lower stratosphere through its interaction with chlorine. A
crude calculation indicates that for chlorine at its 1983 concentrations
to cause the 0.6% per day decline in September would require all of the
chlorine to be in its active state, i.e. Cl and CIO with little or no
interference from NOx. Thus a mechanism must be found which removes the
chlorine from both the HC1 and C10N02 reservoirs and ties up NOx,
preferably as HN03.
Until such a mechanism is found and demonstrated correct, it is not
clear what the implications are for global predictions of the effects of
fluorocarbons on stratospheric ozone. The magnitude of the predicted
fluorocarbon effect on ozone has been uncertain because of the
interaction among the chlorine, nitrogen and hydrogen containing species
and ozone itself. The constraint placed on a chlorine mechanism by the
data appears to require stripping away these interactions under special
conditions and observing the pure active chlorine effect on ozone. The
reactions forming this simple catalytic cycle have never been in much
doubt.
https://ntrs.nasa.gov/search.jsp?R=19910073957 2020-03-17T14:52:55+00:00Z


Nimbus 7 SBUV/TOMS measurements of the springtime Antarctic ozone hole

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server