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Appendix A
PERTURBATIONS OF THE STRATOSPHERE AND OZONE DEPLETION
Ralph J. Cicerone
National Center for Atmospheric Research
Boulder, Colorado
HISTORICAL BACKGROUND
Central to the concern that man's activities can modify
the atmospheric ozone layer is the concept of chemical
catalysis. A substance is a catalyst if it serves to
drive or enhance a process or reaction--without itself
being consumed in the process. In the earth's strato-
sphere, nitric oxide, NO, can catalyze the destruction of
ozone through the cyclic chain reactions:
NO + O
O3 + he
NO2 + O
NO2 + O2
O2 + O
NO + O2
O3 + O3 + he ~ 3O2 (net).
The corresponding catalytic chain reaction involving
chlorine atoms proceeds through:
C1 + O3 +
O3 + he
C10 + O
C10 + O2
O2 + O
C1 + O2
O3 + O3 + he + 3O2 (net).
In these reactions, NO and C1 are not consumed as they
destroy O3 because they are regenerated in the last
reaction of the cycle. Chemical catalysis can be an
extremely efficient process; some industrial catalysts
mediate millions of cyclical reactions before they
themselves require regeneration. The number of times
that the catalytic cycle proceeds is called the chain
length. With a chain length of 10,000 one can see how a
145
OCR for page 146
146
substance present at part per billion concentrations is
capable of chemically controlling another substance
present at 10 parts per million.
me realizations that (a) efficient reactions like
these were occurring in the natural stratosphere and (b)
certain pollutants could mimic nature's ozone-destroying
catalytic cycles were nearly simultaneous and have helped
measurably to improve our understanding of the natural
atmosphere and of man's potential for perturbing it. The
research of Crutzen (1970, 1971) and Johnston (1971)
showed that natural nitrogen oxides and aircraft-injected
NO could have important roles in counterbalancing natural
ozone production and providing extra, artificial ozone-
destroying capacity, respectively. Earlier the need for
identifying unspecified natural loss processes for strato-
spheric ozone had been noted by Hampson (1964) and Hunt
(1966), who based their work on earlier theory from Bates
and Nicolet. The proposal (Berkner and Marshall 1967)
that the evolution of life on the exposed earth surface
began with the formation of the ultraviolet light-
absorbing ozone screen, coupled with the realization that
extant or planned human activities could destroy some of
the ozone and a generally growing environmental awareness
caused scientists to respond seriously to suggestions of
stratospheric chemical perturbations. The ongoing release
of synthetic chlorofluorocarbons, shown by Molina and
Rowland (1974) to be capable of delivering chemically
effective amounts of ozone-destroying chlorine atoms to
the stratosphere, remains in 1981 the largest and most
plausible threat. The biological UV-shield function of
atmospheric ozone has focused attention on chemical
pollutants capable of reducing the total amount of ozone
in a vertical column of the atmosphere. Proposed fleets
of stratospheric supersonic aircraft (releasing NO and
H2O), space shuttle rockets (releasing HC1), the use of
bromine-containing chemicals, the surface release of
N2O from agricultural nitrogen-fertilizer usage and
from some types of fuel combustion, and the emissions to
the air of certain chlorinated solvents have been
proposed as possible ozone reducers. Research in the
United States and elsewhere (as documented in earlier NRC
and NASA reports) has focused too narrowly on possible
reductions in the total vertical column of ozone in the
stratosphere--probably because of the UV shield that
ozone provides to life on earth. Too little emphasis has
been placed on inquiring whether ozone spatial redistribu-
tions (in altitude and latitude) can result from man's
OCR for page 147
147
activities. Climatic effects could ensue from large
redistributions. Further, tropospheric ozone (about 10
percent of total atmospheric ozone) has been relatively
unstudied. Until recently, the prevailing view has been
that the only interesting tropospheric photochemistry
involving O3 takes place in highly polluted urban
areas. Better understanding of tropospheric chemistry
and more complete photochemical kinetic data bases are
changing this view, and consequently a fuller concept of
man's impact on atmospheric ozone is emerging.
NATURAL PERTURBATIONS TO ATMOSPHERIC OZONE
Both the chemical and the dynamical forces that control
the atmospheric ozone distribution are subject to natural
perturbations and variations. It is important to under-
stand the consequent natural ozone responses and
variability; cause-effect relations must be fathomed if
we are to be able to predict ozone changes. The very
existence of natural variations affects our ability to
detect secular trends in ozone.
On human time scales the most pertinent natural pertur-
bations to atmospheric ozone appear to arise from: solar
proton events, relativistic electron bombardments, quasi-
biennial oscillation (and temperature change) effects,
temperature changes on other time scales, and, possibly,
11-year solar W irradiance changes and volcanic chemical
inputs.
In August of 1972, a burst of solar protons entered
the high-latitude atmosphere. High-latitude ozone
amounts were observed to decrease almost simultaneously
by the Nimbus 4 B W instrument (Heath et al. 1977, Reagan
et al. 1981); these decreases persisted for several weeks.
The first theoretical analysis of the effects of this
solar proton event (Heath et al. 1977 ) found good quali-
tative agreement between observed O3 decreases and
those calculated in a 2-dimensional parameterized trans-
port model including only the direct chemistry, i.e.,
ion-pair production by proton impact, dissociative
recombination to yield NO, then NO-catalyzed O3
depletion. Recently, Solomon and Crutzen (1981) have
expanded the computational model's chemistry to include
chlorine chemistry and the production of hydrogen oxides
(HOx) by the arriving protons. They also included the
expected temperature-decrease feedback in their model.
Their calculated O3 decreases due to the solar protons
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148
agreed very well with the measured decreases except above
50 km. A further analysis has been performed by McPeters
et al. (1981), who have provided certain corrections to
the Heath et al. (1977) B W ozone data. The revised
August 1972 data on the ozone perturbation evidently
agree more closely with Solomon and Crutzen's calculated
ozone reductions. McPeters and coworkers also analyzed
two earlier (1971) smaller solar-proton events after
which high-altitude ozone was observed to be depleted;
the measured O3 depletions were larger than McPeters
and co-workers calculated with their photochemical
model. All of these investigations, when combined with
earlier studies of a 1969 solar proton event and observed
ozone reductions (Weeks et al. 1972, Swider and Kene she a
1973), have utilized a natural NOx-injection event to
establish that NOX catalytic cycles do reduce ozone in
the middle and upper stratosphere.
Natural variations in the solar W output may have
influenced stratospheric ozone during the recent past
when Dobson instruments and satellite instruments have
measured ozone. While there is no argument in principle
that W irradiance changes would modulate ozone amounts,
there is disagreement over the reality of solar cycle
variations in W irradiance. Recently, Brasseur and
Simon (1981) have expressed this concern, reviewed
earlier calculations and presented new calculations of
altitude, latitude, and temporal problems to be expected
from solar-cycle-related W changes. A more empirical
approach has been taken by Keating et al. (1981) and
Reber and Huang (1982). From the monthly global average
ozone amounts derived from Nimbus IV B W measurements
(1970-1977), Tolson (1981) and Keating et al. (1981)
sought an empirical relationship between solar W output
(as indicated by the 10.7-cm radiowave flux) and global
total ozone. They found a very high correlation between
the two; this strong correlation suggested a causal
relationship. An independent analysis by Reber and Huang
(1982) shows that much of this correlation is due to a
secular trend in both. Further, the remaining correla-
tion maximizes for a zero time lag or for ozone changes
one month preceding the 10.7-cm flux change. Coupled
with the uncertainty (several references cited by Reber
and Huang) in the stability of the BUV instrument for
total ozone measurements over this seven-year time
period, firm conclusions about relationships between
total ozone and solar UV seem impossible at this time
(Reber and Huang 1982). Thus, while photochemical theory
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149
calls for such a relationship, it has been difficult to
observe.
Perturbations to stratospheric ozone can also be
caused by altered circulation patterns or temperature
fields. Episodic phenomena such as sudden stratospheric
warmings should affect ozone, but more interesting for
our present purpose are those large-scale temperature
changes that can be sustained for a year or more.
Recently, Angell has extended earlier analyses that have
found a significant cooling of the upper stratosphere
(cited in Hudson et al. (1982)). In the 46- to 55-km
region there has been about a 5°K cooling between 1971
and 1980; a less pronounced cooling is evident down to 36
km. Such a cooling should have led to slightly larger
local ozone concentrations. These were not observed by
Heath with the NIMBUS IV B W instrument.
reported ozone decreases of nearly 9 percent at the 40-km
level from 1971 to 1977 (NASA/WMO Stratosphere Workshop,
Hampton, Virginia, May 18-22, 1981; see also Science,
September 4, 1981, pp. 1088-1089).
It is also important to recognize the possibility of a
large natural change in tropospheric ozone, both because
the ozone column would be affected and because of possible
climatic effects that could ensue. Data suggest that
northern hemispheric tropospheric ozone has increased
substantially in the last decade; this is discussed below.
Instead, he
Finally, although explosive volcanoes can in principle
affect stratospheric ozone by direct injections of water
and chlorine, there are no indications of measurable
effects due to volcanoes during the life of the Dobson
instrument network. A related question involves the
ability of stratospheric dust to confound the Dobson
measurement technique (Dave et al. 1981, De Luisi et al.
1975). One would feel more confident with a complete
absorption spectrum rather than discrete wavelength pairs
at which absorption is measured.
MAN'S IMPACT: ASSESSMENT AND UNCERTAINTY IN 1981
Of all the potential anthropogenic influences on
atmospheric ozone the continued release of chlorofluoro-
carbons 11 and 12 and of trichloroethane remains in 1981
that of most immediate and apparently largest concern.
The anticipated magnitude of the effect continues to
change as the laboratory photochemical data base grows.
It is worth noting that there have been few, if any,
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150
results reported from coupled meteorological/chemical
model calculations. Our estimates of man's impact on
ozone due to fluorocarbon release continue to be based on
models that have not changed conceptually since before
the fluorocarbon problem was identified. Further, even
the most elegant and difficult field measurements such as
the C1 and C1O profile measurements of Anderson et al.
(1980) and those of total chlorine in the lower strato-
sphere by Berg et al. (1980) have not altered the initial
view of this environmental problem. Field measurements
in general have substantiated all elements of the original
Molina-Rowland hypothesis; quantitative adjustments to
the size of the ozone perturbation have arisen frequently
from new or changed laboratory kinetic data.
If we focus on the expected reduction in total ozone
due to continued release of CF2C12 and CFC1~ at
1~h=; ~ 1 Ode; :~^r~ll~l r:~^c icon it Zi 1 ~
-arc-- -I ~- -any- `~~~ ~ -- Meal r we see that
major changes have resulted from altered chemical
reaction rates and from the inclusion of previously
omitted reactions and species (e.g., ClNO3 and HNO4).
The calculations that produced Figure A.1 were performed
with 1-dimensional photochemical models with parameter-
ized transport. Since 1980 there have also been similar
2-dimensional models that have been able to include as
20
z
o
0 15
z
LL
co
~ 10
cr:
LU
z 5
c:
A:
c
20
~ A / CFM Release
~ ~~~~~~~
~- __ N2O Doubling
15
.'
10
_ 5
1974 1975 1976 1977 1978 1979
RATE
CONSTANT Cl OH+
REVISIONS HO2
CIONO2 NO + HO2 2ppb
Clx
I'
1 980 1 98 1
__~
OH + HNO3
HNO4 + he
OH + HNO4
OH + H2O2
OH + HO2
FIGURE A.1 Brief schematic history of the estimates of the steady state column
ozone reduction due to (a) continued release of CF2C12 and CFC13 at 1975 annual
rates, and (b) doubling of N2 O (from 300 to 600 ppb). More detail on reasons for
changes between 1979 and 1981 is in Hudson et al. (1982, Chapter 3~.
OCR for page 151
151
many chemical processes as the preexisting 1-dimensional
models. The change in globally averaged total ozone
amounts due to CF2C12 and CFC13 from the available
2-dimensional models is very close to that from 1-
dimensional models (see Chapter 3 of Hudson et al.
(1982)). As Figure A.1 indicates, since 1979 there has
~ . .~ ~ ~ a
been a considerable downward revision or one preen cues
steady state ozone depletion. With currently accepted
chemical reaction rates one calculates steady state,
globally averaged ozone reductions of perhaps 6 percent.
The principal chemical data changes since 1979 are:
(i) a faster rate for OH + HNO3 ~ H2O + NO3
especially at low temperatures, (ii) a faster rate for OH
+ H2O2 ~ H2O + HO2, (iii) slower photolysis of
HNO4 than previously measured, (iv) faster reaction of
OH + HNO4 + products, presumably H2O + NO2 + O2
than originally estimated, and (v) upward revision of the
OH + HO2 rate constants. Key references for these
recent changes are:
(i) Wine et al. (1981); (ii) Keyser
(1981) and Kaufman (1980); (iii) Molina and Molina
(1981); (iv) and (v) NASA/JPL Kinetics Panel (1981).
While these changes have the effect of lowering
calculated OH (and C1O) concentrations below 30 km and
thus permitting more favorable comparison with Anderson's
C1O measurements below 30 km than before (Cicerone and
Walters 1980, Duewer and Wuebbles 1980, Sze and Ko 1981),
they are not the final word (see next paragraph). It
would not be surprising if the best estimates of column
ozone changes due to CF2C12 and CFC13 and N2O
increases continue to oscillate as on Figure A.1.
More detail on the chemical reaction rates that have
changed since 1979 and the effect each change has had on
ozone-depletion predictions can be found in Chapter 3 of
Hudson et al. (1982). The effects of each of the
processes mentioned above as well as discussion of recent
findings on the reactions HO2 + C1O ~ products and
C1O + NO2 ~ products (isomers of C1NO3) are spelled
out in that report. The remaining uncertainties in every
one of these processes except OH + H2O2 ~ H2O +
HO2 are considerable. Unfortunately, most of these
processes involve working with notoriously difficult
laboratory systems, e.g., any study of HNO4 properties
and the reactions of the radicals like OH + HO2.
Besides the laboratory kinetic uncertainties one must
also note that measurements of most of these apparently
important polyatomic species in the atmosphere have not
yet been achieved: there has been no positive detection
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152
of ClONO2 (chlorine nitrate), H2O2, HOC1, HNO4,
or N2O5. In this regard, one must state that there
is considerable remaining uncertainty in ozone-depletion
estimates. As with most scientific questions,
in this
case there is uncertainty on the high and low sides,
i.e., if certain predicted species do not actually exist
or certain reactions proceed at predicted rates, the
curves on Figure A.1 could go in either direction. To
make matters worse, these key polyatomic species are
predicted to exist (and to mediate the critical chemistry)
in the lower to middle stratosphere, precisely where
physical transport in dynamical meteorological systems is
important and simple photochemistry is not the controlling
factor. Accordingly, it appears that the resolution of
present uncertainties involving chlorine nitrate, HOC1,
HNO4, H2O5, H2O2, etc., will require not only
difficult laboratory measurements but much more complete
coupling of chemical and dynamical meteorology models.
Phrased in the terminology of chemical catalysis, we must
be able to calculate the catalytic chain lengths of the
chlorine and nitrogen oxide chains and the effectiveness
of the methane-oxidation ozone production reactions.
Such a calculation must accurately account for (a)
processes that can interrupt catalytic chains that form,
for example, HNO4 or HOC1 or ClONO2, and (b)
meteorological motions that can rapidly move the reacting
chemicals to locations with different pressures and
temperatures.
The possibility of a separate anthropogenic effect on
atmospheric ozone has been raised by Liu et al. (1980).
In a research report concerned with the natural origins
of tropospheric ozone they found evidence that ozone
produced photochemically in the upper troposphere where
subsiding stratospheric NOX encounters rising nyaro-
carbons. If so, then the NOX emitted by commercial and
military subsonic aircraft should lead to ozone production
near the 10 km (flight altitude) level. Liu et al. (1980)
calculated that increased subsonic air traffic could have
increased northern hemispheric tropospheric ozone by about
15 percent from 1970 to 1980. Such an increase, while
important in its own right, would also amount to a 1.5
percent increase in total overhead ozone. This increase
could mask a 1.5 percent decrease in the stratospheric
ozone column. At eight of nine northern hemisphere
stations where tropospheric ozone profiles are measured
regularly there was a measured increase of about the
predicted amount (Liu et al. 1980). This apparent
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153
increase in northern hemispheric tropospheric ozone has
also been discussed by Pittock (see Appendix F) and in
the 1981 NASA/WMO Stratosphere Report (Hudson et al.
1982). From all these sources it appears clear that an
increase might have occurred but the present state of
measurement capability for tropospheric ozone above the
surface is poor enough to be unable to settle this
question.
The changes in our photochemical reaction schemes and
data of the past two years have had relatively little
effect on our view of the upper stratosphere. One still
expects ozone at the 40-km level to be strongly attacked
by chlorine compounds. No serious doubt at all exists on
this point; one must state that a stong perturbation of
the upper stratosphere is under way. However, because of
the large uncertainties in the region below 30 km, mostly
with the polyatomic species mentioned above, one cannot
say with much confidence what the total column ozone
depletion will be eventually. It is possible that as the
upper stratospheric ozone decreases and NATO and COD
increase, there could be extra ozone production below
about 25 km so that the vertical column of ozone could be
changed only slightly. In this event there would
probably be a significant redistribution of ozone in
latitude and altitude, leading to concern over climatic
effects.
Two other human activities need updating. First, in
the case of atmospheric N2O, Weiss (1981) has shown
through measurements that N2O has increased by about
0.2 percent per year since 1976 and most likely at a
similar rate since 1963. The relative contributions of
combustion-produced N2O and fertilizer-produced N2O
are not yet clear although Weiss's data can be explained
roughly by the former. Second, atmospheric detonation of
nuclear explosives has been examined once again, and it
appears as before that there are significant uncertainties
in estimating the NO yields (and thus the chemical
effects) of such explosions (McGhan et al. 1981).
RECOMMENDATIONS FOR RESEARCH
Although the exact size of the effect has proven difficult
to predict, the hypothesis that continued chlorofluoro-
carbon release will have a significant global impact on
atmospheric ozone appears correct--it has withstood over
seven years of reexamination. Because of the need for
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154
industry and government to make decisions on production
and regulation and because other global anthropogenic
pollutants (e.g., NOx and N2O) remain items of
concern, further atmospheric chemistry research is
indicated. The goals of the research areas listed below
are (i) to understand relevant atmospheric chemistry and
meteorology well enough to permit better prognostic
mathematical models, (ii) through measurements, to better
characterize the atmosphere's chemical behavior, and
(iii) to obtain more accurate and precise measurements of
atmospheric ozone to permit variations and trends to be
detected earlier and more clearly.
1. Continue the operation, maintenance, and data
analysis of the WMO/NOAA Dobson instrument ozone
measurements.
2. Develop improved ground-based instrumentation for
measurements of the ozone column. It should be feasible
to take entire absorption spectra for ozone determinations
rather than the isolated measurements at a few discrete
wavelengths. We are fortunate to have the Dobson
instruments, but one suspects that it is possible to
improve accuracy and precision with modern techniques
(the Dobson instrument was invented in 1927).
3. Develop improved methods for measurements of
tropospheric ozone. Both lidar and stable chemical
sensors seem like good prospects.
4. Continue and expand, if possible, in situ
measurements of key chemical species and the ratios of
key reactive species in spatial regions where the
reactants are important and where photochemical time
constants are smaller than those for transport.
5. Accelerate the development of mathematical models
of atmospheric chemistry with coupled atmospheric
dynamical fluid motions.
6. Encourage extant models to focus on more
complicated scenarios, e.g., increasing CFMs and
increasing CO2 and increasing N2O, CH4, and
CH3CC13.
7. Accelerate research on climatological effects of
redistribution of atmospheric ozone and of trace gas
increases.
8. Continued monitoring of background concentrations
of CF2C12, CFC13, N2O, and CH4. While no
evidence exists for tropospheric removal processes of
CF2C12, CFC13, or N2O, it is very important to
obtain a continuous record of their concentrations. The
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155
preparation and stable maintenance of calibrated standards
for each of these gases is still an important research
problem deserving commitment of government and industrial
resources and scientific talent.
.
9. Improved satellite sensors and continued data-
reduction effort focused toward stratospheric ozone and
trace-constitutent monitoring are needed.
10. Expanded high-altitude (upper stratospheric)
whole-air sampling is needed to obtain vertical profiles
of H2O, CH4, and N2O and other stable trace gases.
These are needed to provide ground truth values for
overflights of satellite sensors and to begin to acquire
a climatology of the upper stratosphere for multi-
dimensional models to employ in validation tests.
REFERENCES
Anderson, J.G., H.J. Grassl, R.E. Shetter, and J.J.
Margitan (1980) Stratospheric free chlorine measured
by balloon-borne in situ resonance fluorescence.
Journal of Geophysical Research 85:2869-2887.
Berg, W.W., P.J. Crutzen, F.E. Grahek, S.M. Gitlin, and
W.A. Sedlacek (1980) First measurements of total
chlorine and bromine in the lower stratosphere.
Geophysical Research Letters 7:937-940.
Berkner L.W. and L.L. Marshall (1967) The rise of oxygen
in the earth's atmosphere with notes on the martian
atmosphere. Advances in Geophysics 12:309-331.
Brasseur, G. and P.C. Simon (1981) Stratospheric chemical
and thermal response to long-term variability in solar
UV irradiance. Journal of Geophysical Research
86:7343-7362.
Cicerone, R.J. and S. Walters (1980) NO2-Catalyzed
Removal of Stratospheric BOX. Paper presented at
Fourteenth Informal Conference on Photochemistry,
March 31. (unpublished)
Crutzen, P.J. (1970) The influence of nitrogen oxides on
the atmospheric ozone content. Quarterly Journal of
the Royal Meteorological Society 96:320-325.
Crutzen, P.J. (1971) Ozone production rates in an oxygen-
hydrogen-nitrogen oxide atmosphere. Journal of
Geophysical Research 76:7311-7327.
Dave, J.V., C.L. Mateer, and J.J. De Luisi (1981) An
examination of the effect of haze on the short Umkehr
method for deducing the vertical distribution of
ozone. Pages 222-229, Proceedings of the Quadrennial
\
OCR for page 156
156
International Ozone Symposium, August 4-9, 1980
Boulder, Colo.: National Center for Atmospheric
Research.
De Luisi, J.J., B.M. Herman, R.S. Browning, and R.K. Sato
(1975) Theoretically determined multiple-scattering
effects of dust on Umkehr observations. Quarterly
Journal of the Royal Meteorological Society
101:325-331.
Duewer, W.H. and D.J. Wuebbles (1980) Effects of
Speculative Reactions and Mechanisms on Predicted
Ozone Perturbations. Paper presented at Fourteenth
Informal Conference on Photochemistry, April 1.
(Unpublished)
Hampson, J.F. (1964) Photochemical Behavior of the Ozone
Layer, CARDE Technical Note 1627/64, Canadian Armament
Research and Development Establishment, Valcartier,
Quebec, 280 pp.
Heath, D.F., A.J. Krueger, and P.J. Crutzen (1977) Solar
proton event: Influence on stratospheric ozone.
Science 197:886-887.
Hudson, R.D., et al., eds. (1982) The Stratosphere 1981:
Theory and Measurements. WHO Global Research and
Monitoring Project Report No. 11. Geneva: World
Meteorological Organization. (Available from National
Aeronautics and Space Administration, Code 963,
Greenbelt, Md. 20771.)
Hunt, B.G. (1966) The need for a modified photochemical
theory of the ozonosphere. Journal of Atmospheric
Sciences 23:88-95.
Johnston, H.S. (1971) Reduction of stratospheric ozone by
nitrogen oxide catalysts from supersonic transport
exhaust. Science 173:517-522.
Kaufman, F. (1980) Laboratory Measurements of Strato-
spheric Reactions: Recent Results and Their
Interpretation. Paper presented at Fourteenth Informal
Conference on Photochemistry, March 31. (Unpublished)
Keating, G.M., L.R. Lake, J.Y. Nicholson, and M.
Natarajan (1981) Global ozone long-term trends from
satellite measurements and the response to solar
activity variations. Journal of Geophysical Research
86. (In press)
Keyser, L.F. (1980) Kinetics of the reaction OH +
H2O2 ~ HO2 + H2O from 245°K to 423°K. Paper
presented at Fourteenth Informal Conference on
Photochemistry, April 1. (Unpublished)
Liu, S.C., D. Kley, M. McFarland, J.D. Mahlman, and H.
Levy (1980) On the origin of tropospheric ozone.
Journal of Geophysical Research 85:7546-7552.
OCR for page 157
157
McGhan, M., A. Shaw, L.R. Megill, W. Sedlacek, P.R.
Guthals, and M.M. Fowler (1981) Measurements of nitric
oxide after a nuclear burst. Journal of Geophysical
Research 86:1167-1173.
McPeters, R.D., C.H. Jackman, and E.G. Stassinoupoulos
(1981) Observations of ozone depletion associated with
solar proton events. Journal of Geophysical Research
86:12071-12081.
Molina, L.T. and M.J. Molina (1981) Ultraviolet absorption
cross sections of HO2NO2 vapor. Journal of Photo-
chemistry 15:97-108.
Molina, M.J. and F.S. Rowland (1974) Stratospheric sink
for chlorofluoromethanes: Chlorine-atom catalyzed
destruction of ozone. Nature 249:810-812.
NASA/JPL Kinetics Panel (1981) Chemical Kinetic and
Photochemical Data for Use in Stratospheric Modeling.
Evaluation No. 4: NASA Panel for Data Evaluation. JPL
Publication No. 81-3. Pasadena, Calif.: California
Institute of Technology.
Reagan, J.B., R.E. Meyerott, R.W. Nightingale, R.C.
Gunton, R.G. Johnson, J.E. Evans, and W.L. Imhof
(1981) Effects of the August 1972 solar particle
events on stratospheric ozone. Journal of Geophysical
Research 86:1473-1494.
Reber, C.A. and F.T. Huang (1982) Total ozone-solar
activity relationship. Journal of Geophysical Research
86. (To be published Feb. 1982).
Solomon, S. and P.J. Crutzen (1981) Analysis of the
August 1972 solar proton event including chlorine
chemistry. Journal of Geophysical Research
86:1140-1146.
Swider, W. and T.J. Keneshea (1973) Decrease of ozone and
atomic oxygen in the lower mesosphere during a PCA
event. Planetary and Space Science 21:1969.
Sze, N.D. and M.K.W. Ko (1981) The effects of the rate
for OH + HNO3 and HO2NO2 photolysis on
stratospheric chemistry. Atmospheric Environment
15:1301-1307.
Tolson, R.H. (1981) Spatial and temporal variations of
monthly mean total column ozone derived from 7 years
of B W data. Journal of Geophysical Research
86:7312-7330.
Weeks, L.H., R.S. Cuikey, and J.R. Corbin (1972) ozone
measurements in the mesosphere during the solar proton
event of 2 November 1969. Journal of Atmospheric
Sciences 21:1138.
OCR for page 158
1~°
Weiss, R.~. (1981) The temporal and spatial distribution
of tropospheric nitrous oxide. Journal of Geophysical
Research 86:7185-7196.
Wine, P.~., A.~. Ravishankara, N.M. Kreutter, R.C. Shah,
J.M. Nicovich, R.L. Thompson' and D.J. Wuebbles (1981)
Rate of reaction of OH with HNO3. Journal of
Geophysical Research 86:1105-1110.
Representative terms from entire chapter:
geophysical research
