February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 1, NUMBER 6, DECEMBER 1988
ANTARCTIC OZONE HOLE
"How Deep is an `Ozone Hole'?" (correspondence), Nature,
336(6196), 198, Nov. 17, 1988.
"Stratospheric NO2 Over Antarctica as Measured by the Solar
Mesophere Explorer During Austral Spring, 1986," R.J. Thomas (Lab. Atmos.
Space Phys., Campus Box 392, Univ. Colorado, Boulder CO 80309), K. Rosenlof et
al., J. Geophys. Res., 93(D10), 12,561-12,568, Oct. 20, 1988.
Vertical profiles indicate that the bulk of the NO2 column lies above 24 km.
Comparison of measurements and model calculations imply that much of the odd
nitrogen is converted to HNO3 during the polar night. Overall, observed behavior
does not appear to be anomalous when compared to simple model calculations,
indicating no obvious connection between the polar stratospheric NOx above 24 km
and the development of the ozone hole below 24 km.
"Coherent Ozone-Dynamical Changes During the Southern Hemisphere
Spring, 1979-1986," P.A. Newman (Appl. Res. Corp., 8201 Corp. Dr., Landover
MD 20785), W.J. Randel, ibid., 12,585-12,606.
Describes a careful analysis of stratospheric temperature and wind data and
a search for changes that are coherent with the observed ozone changes, to
determine the relative roles of chemical or dynamical mechanisms in ozone
depletion. Virtually perfect spatial correlation is found between October
average lower stratospheric temperatures and total ozone for each year. In
addition to ozone variability correlated with observed temperature changes,
there is a substantial decline not linearly related to the observed temperature
"Antarctic Springtime Ozone Depletion Computed From Temperature
Observations," J.E. Rosenfield (NASA Goddard Space Flight Ctr., Greenbelt
MD 20852), M.R. Schoeberl, P.A. Newman, ibid., 93(D4),
3833-3849, Apr. 20, 1988.
Vertical velocities derived from observed stratospheric temperature changes
and computed radiative heating rates are used to advect an ozone mixing ratio
profile during the Antarctic spring period. The model reasonably simulates the
September and October changes in total ozone. The simulated decline is found to
be very sensitive to the choice of initial ozone profile and to small changes in
the radiative heating. Results suggest that the dynamical hypothesis of the
Antarctic ozone depletion is both quantitatively credible and consistent with
the observed temperature changes.
"Aerosol Measurements in the Winter/Spring Antarctic
Stratosphere--1. Correlative Measurements with Ozone," D.J. Hofmann (Dept.
Phys., Univ. Wyoming, Laramie WY 82071), J.M. Rosen, J.W. Harder, ibid.,
93(D1), 665-676, Jan. 20, 1988.
As tracers of atmospheric motions, aerosol measurements can help sort out
chemical and dynamical effects in the springtime ozone depletion problem. The
height of the stratospheric sulfate layer was found to decrease, indicating
subsidence in the vortex during the period that ozone was decreasing. This
suggests that upwelling in the vortex is not important in the ozone depletion
process. Enhanced condensation nuclei above 20 km in the vortex and the
discovery of an apparent permanent layer in the springtime vortex at the top of
the ozone depletion region suggests that they may be related to ozone depletion.
2. Impact on Polar Stratospheric Cloud Theories," J.M. Rosen
(address immed. above), D.J. Hofmann, J.W. Harder, ibid., 677-686.
Discusses three major theories of polar stratospheric cloud (PSC) formation
and the impact of the new measurement on each of them. Aerosol observations
indicate that the possibility these clouds are low concentrations of relatively
large (>> 5 micro m) particles must be taken seriously.
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