February 28, 2007
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A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 6, NUMBER 6, JUNE 1993
GENERAL INTEREST--SCIENCE: OZONE DEPLETION
"Record Low Global
Ozone in 1992," J.F. Gleason (NASA-Goddard, Greenbelt MD 20771), P.K.
Bhartia et al., Science, 260(5107), 523-536, Apr. 23, 1993.
The 1992 global average total ozone, measured by the Total Ozone Mapping
Spectrometer on the Nimbus-7 satellite, was 2-3% lower than any earlier year
observed (1979-1991). Ozone was low in a wide range of latitudes, with the
largest decreases in the bands 10·S to 20·S and 10·N to 60·N.
Global ozone in 1992 was at least 1.5% lower than would be predicted by a
statistical model that includes a linear trend and accounts for solar cycle
variation and the quasi-biennial oscillation.
Two related items from
Nature, 362(6421), Apr. 15, 1993:
"Satellite Maps Ozone Destroyer," M. Chipperfield (Dept. Chem.,
Univ. Cambridge, Cambridge CB2 1EW, UK), 592-593. Gives a research perspective
on the following article.
"Stratospheric ClO and Ozone from the Microwave Limb Sounder on the
Upper Atmosphere Research Satellite," J.W. Waters (Jet Propulsion Lab.,
4800 Oak Grove Dr., Pasadena CA 91109), L. Froidevaux et al., 597-602. Reports
the first 18 months of measurements by this instrument of ClO (the main form of
reactive chlorine responsible for ozone depletion) and ozone. Chlorine in the
lower stratosphere was almost completely converted to chemically reactive forms
in both the northern and southern polar winter vortices. Concludes that chlorine
depletion of stratospheric ozone is of greater concern than previously thought.
Chlorine Injection by Volcanic Eruptions: HCl Scavenging and Implications for
Ozone," A. Tabazadeh (Dept. Atmos. Sci., Univ. California, Los Angeles CA
90024), R.P. Turco, Science, 260(5010), 1082-1086, May 21, 1993.
Although the output of volatile chlorine during a major volcanic event can
greatly exceed the annual anthropogenic emissions of chlorine, observations show
that volcanoes do not significantly contribute to the atmospheric chlorine
burden. This paper uses a plume dynamics and thermodynamics model to demonstrate
that HCl is removed effectively in condensed supercooled water, providing for
the first time a mechanism explaining the observations, and supporting the
importance of the anthropogenic contribution to ozone depletion.
Dioxide over Antarctica Caused by Volcanic Aerosols from Mount Pinatubo,"
S. Solomon (NOAA, 325 Broadway, Boulder CO 80303), R.W. Sanders et al., Nature,
363(6426), 245-248, May 20, 1993.
Levels of ClO were found to be elevated in the autumn of 1991, when polar
stratospheric clouds were extremely unlikely to have been present, compared to a
previous year. Model runs suggest that this result is related to the presence of
Pinatubo aerosols, which probably contributed to the unprecedented depth and
areal extent of Antarctic ozone depletion in 1992.
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