Ozone Depletion, Greenhouse Gases, and Climate Change (1989) / Chapter Skim
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4 Stratospheric Ozone Depletion: Antartic Processes
4 Stratospheric Ozone Depletion: Antartic Processes
Pages 19-32
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From page 19... ...
It is worth noting that the appearance of the ozone hole was an unexpected event in the sense that the models referred to by Albritton did not predict the hole. The ozone hole has made modelers realize that stratospheric modeling needs further work and has rekindled scientific interest in the problem of stratospheric ozone.
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From page 20... ...
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From page 21... ...
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From page 22... ...
Other ozonesonde data from the South Pole, McMurdo, and Halley Bay stations, stations that were continually in the polar vortex region of depletion, show an almost complete disappearance of ozone after October 5. Hence, the ozone hole was a continent-wide phenomenon extending out to around the latitude of the Palmer station, where a steep horizontal gradient of ozone exited.
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From page 23... ...
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From page 24... ...
The relatively high sun angle of November and December coupled with this shift in the location of the ozone minimum likely resulted in a significant UV impact on the aquatic ecosystem of that region. Further comparison of 1987 with earlier years indicates a progressively more rapid decrease of ozone during September in the later years.
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From page 25... ...
The unique meteorology of the antarctic region in the winter and spring seasons results in the development of a strong polar vortex that consists of an air mass that ~ largely isolated from air farther north. Within the vortex, temperatures become cold enough to form stratospheric ice crystals.
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From page 26... ...
the Chemical Manufacturers Association, and the National Science Foundation collaborated on ground-based expeditions to McMurdo in both 1986 and 1987 and provided extremely important results. These included observations of chlorine dioxide by Susan Solomon, which served as a very good indicator of perturbed chlorine chemistry, as well as measurements of very low nitrogen dioxide, showing that the atmosphere appears to be denitrified.
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From page 27... ...
of total ozone measured by TOMS for the indicated dates. Period shown includes the breakup of the ozone minimum in 1987.
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From page 28... ...
) to determine rising or sinking motions in the air mass, and a large number of aerosol measurements, as well as a system to measure the temperature lapse rate (Bruce Gary, Jet Propulsion Laboratory (IMPLY.
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From page 29... ...
Thus, the vortex atmosphere on this date was dehydrated, denitrified, and highly enriched in chlorine oxides, but with little effect on ozone levels. By the end of our mission on September 22, the polar vortex atmosphere was still dehydrated and denitrified, the chlorine oxides had increased to about 1 ppbv, and the ozone concentration had dropped to less than half of its value outside the vortex.
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From page 30... ...
The DC-8 flew nearly to the South Pole and obtained many bulk column measurements. These show that, in crossing inside the polar vortex, nitrogen dioxide drops off significantly, nitric acid peaks around 70°S and then drops, chlorine nitrate reaches a maximum at the edge of the vortex, and hydrochloric acid fails off significantly within the vortex.
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From page 31... ...
Answer: ~ have heard two different definitions of the vortex. They are based on the location of the steepest potential vorticity gradient and the location of the jet of maximum winds, which is about 5 to 8° of latitude wide.
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From page 32... ...
Answer: The next two papers address that question. The evidence that ~ have seen from laboratory studies indicates that liquid sulfuric acid particles will not provide such an efficient surface for heterogeneous chemistry, partly because the rate of reaction proceeds more slowly compared to that with ice crystals, and partly because the typical density of the sulfuric acid aerosols is less than that for ice crystals over Antarctica.
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