Causes and Effects of Stratospheric Ozone Reduction An Update (1982) / Chapter Skim
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D THE MEASUREMENT OF TRACE REACTIVE SPECIES IN THE STRATOSPHERE: A REVIEW OF RECENT RESULTS
D THE MEASUREMENT OF TRACE REACTIVE SPECIES IN THE STRATOSPHERE: A REVIEW OF RECENT RESULTS
Pages 206-305
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From page 206... ...
The ordering of groups and of the species within each group in the table is rather arbitrary, but the choice seeks to represent the fact that the central objective of this report is an assessment of the effect of fluorocarbon release on stratospheric ozone. Thus, the photochemically active chlorine components are treated first.
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· ~ ~ ~ _ how well the current data base constrains morel prealctions of ozone reduction. ~ uncertainties in the reaction rate constant data by defining a series of six "cases," tracing the impact of rate constant assumptions on the key free radicals and on the altitude dependence of odd oxygen destruction.
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first linked fluorocarbon release to global ozone reduction. In addition, because C1O dominates the chlorine free radical system with respect to concentration, reaching nearly 1 part per billion (ppb)
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All observations contained in Figure D.1 represent midday conditions at 32°N latitude; variations in solar zenith angle primarily reflect changes in solar declination. The in situ observations fall into two classes; 8 of the 10 define an envelope with deviations limited to about +50 percent about the observed mean; two of the observations, both obtained in July, fall clearly outside of the envelope and are not representative of the mean distribution of C10 at middle latitudes.
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10 9 10'. FIGURE D.1 Summary of the vertical distribution of C10 obtained between July 28, 1976, and September 26, 1979, using in situ resonance fluorescence methods (from Weinstock et al.
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broadening by approximately 4 MHz/mb at stratospheric pressures. This is both a blessing, in that low-resolution altitude information can be extracted from the emission line shape, and a curse, in that one must have a first-order estimate of the shape of the emitting layer in order to obtain the absolute column concentration for the observed brightness temperature as a function of frequency.
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From page 215... ...
These figures compare the line shape that would be observed for three modeled cases: Case (a) with a mixing ratio of 2.7 ppb for total chlorine, a chemical reaction scheme comparable to that used for the previous NRC report, and an elevated stratospheric water vapor mixing ratio of 8 ppm (uniform from troposphere to stratosphere, as discussed in Logan et al.
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From page 216... ...
(1978) with 8 ppm H2 O throughout the stratosphere; Case b with 5 ppm H2 O and 2.3 ppb total chlorine from Sze and Ko (1981~; and Case c for 5 ppm H2O and 1.3 ppb total chlorine from Crutzen et al.
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From page 217... ...
There have been no reported observations of the radical C100 in the stratosphere, and there have been no concerted attempts to observe it. Because of its large cross section for photolysis, it is expected to exist at extremely small concentrations, well below currently available detection techniques.
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From page 218... ...
/[C10] 10-1 FIGURE D.6 Comparison between the observed and the calculated ratio of atomic chlorine to ClO (from Anderson et al.
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From page 219... ...
First, the high-resolution middle infrared absorption data obtained by five independent research groups constitute a consistent data set that is reviewed in Figure D.7. The uniformity of these middle IR results is not reflected in the survey of the other four methods, the results of which are reviewed in Figure D.8.
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From page 220... ...
40 35 -25 lol 3-10 ~ /~ (( ~ A 109 HC] VOLUME MIXING RATIO ~o-8 FIGURE D.8 HC1 measurements by ground-based spectroscopy, pressure-modulated radiometry, far IR emission, and in situ filter collection.
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From page 221... ...
Group 2: Reactive Trace Species Containing Hydrogen The Hydroxyl Radical (OH) Hydroxyl has been observed in the stratosphere by four independent techniques noted in the chronological order of their application: 1.
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The total column density of terrestrial OH between the instrument and the sun is observed and is dominated by the altitude interval of 25 to 65 km (Burnett 1976, 1977; Burnett and Burnett 1981)
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From page 223... ...
Thus the in situ observations and the comparison between the integrated in situ data and the total column observations relate primarily to the balance between these two reactions and do not involve in a sensitive way the question of OH reactions with nitric acid and pernitric acid. Although the ground-based data will be discussed in detail in the remainder of this section, we extract from
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mixing ratio of OH in the upper stratosphere and mesosphere obtained by rocket-borne spectrophotometer (Anderson 1975)
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mixing ratio of stratospheric OH obtained in situ by molecular resonance fluorescence within a chamber lowered through the stratosphere at a controlled velocity on a parachute (Anderson 1980~.
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All reported PEPSIOS observations were done at Fritz Peak, Colorado, 40°N latitude. Given the cited uncertainty of the in situ observations of +30 percent and of the total column observations of +25 percent, the observed absolute concentrations summarized in Table D.4, are consistent.
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From page 227... ...
227 TABLE D.3 Contribution of Each Altitude Interval to the Integrated Column Altitude Interval 0-5 15-30 30-45 45-60 60-75 75-90 Contribution to Total Integral 1.5 X 1 ol2 3.4 X 1012 3.2 X 101 3 l.9X 1013 8.8 X 1012 4.3 X 1012 Fraction of Integrated Total Integral Column Density 0.02 O.OS 0.46 0.28 0.13 0.06 6 9 X 1013 cm~2 TABLE D.4 Summary of the Comparison Between the Integrated In Situ Results from Balloon and Rocket Data and the Ground-Based Total Column Observation Composite of the In Situ OH Data 69X 1ol3cm-2 Uncertainty: +40 percent Conditions: Midday, 3 2 N 100 90 80 70 60 6 50 40 30 20 10 o Ground-Based Total Column OH 5 7 X 1013 cm-2 Uncertainty: +25 percent Conditions: Midday, 40 N Composite OH Profile - t 42~1o]
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From page 228... ...
228 10 ,'j' z .~ lo 4 _ ,,,,,, `;_~` 0 .~~ A,, O _ ,,' o 3.0 2.0 1.0 see X a Herman \ ""of b Logan et al. \ ' c Liu - d PEPSI OS Observations e Heicklen f Shimazaki and Ogawa 2.0 3.0 FIGURE D.12 The correlation between OH total column density and solar zenith angle expressed as see X comparing the observed and modeled behavior (from Burnett and Burnett 1981~.
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ground-based total column observations provide the following conclusions: 1. There is substantial agreement among the three techniques; the in situ data provide a consistent picture
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From page 230... ...
+2 I +4F PM 1 1 1 1 2.5 2.0 1.5 1.0 secX 1.5 2.0 2.5 FIGURE D.15 Typical example of the oscillatory diurnal behavior of the OH total column, which was a characteristic signature of the summer 1978 data and does not appear to be an instrumental artifact (from Burnett and Burnett 1981~.
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From page 231... ...
This need results not only from the fact that HOX becomes an increasingly important component of the odd oxygen destruction rate below 30 km, but also because the photochemical partitioning of chlorine and nitrogen depends currently on the OH concentration. The Hydroperoxyl Radical (HO2)
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From page 232... ...
The average mixing ratio in the northern hemisphere is 0.576 ppm by volume, and in the southern hemisphere 0.552 ppm. Hydrogen Peroxide (H2O2)
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From page 234... ...
1978 Glr 26r 1 1 1 1 1 1 111 1 1o~1 1 1 1 1 1 1 1 1 1 1 o- 1 o HO2 MIXING RATIO 10-9 FIGURE D.16 The observed midday HO2 mixing ratio from three in situ resonance fluorescence balloon flights (chemical conversion to OH followed by resonance fluorescence) and one In situ sample collection experiment (cryogenic sampling with EPR analysis)
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Water Vapor (H2O) The subject of stratospheric H2O is of sufficient size to preclude its treatment in this summary.
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From page 236... ...
Third, atomic oxygen is the odd oxygen reactant in virtually all catalytic rate limiting steps in the middle and upper stratosphere. There are six reported observations of O(3P)
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From page 237... ...
data obtained by atomic resonance fluorescence methods (Anderson 1980~.
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From page 238... ...
is not involved in any known reaction of stratospheric significance. Interest in its vertical distribution has been confined to auroral regions; there are few measurements applicable to the stratosphere.
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45 ~: 40 0~ 35 ~ 1 1 1 1 1 0.01 0.1 1.0 10 100 MIXING RATIO (ppm) FIGURE D.21 Fall and summer profiles of O2~/\g3.
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From page 240... ...
Those observations are of critical importance to the subject of trace species observations, for they signify the arrival of highly accurate (and precise) in situ methods that have sensitivity and altitude resolution sufficient for detailed analysis of those factors controlling the local production and destruction rates of odd oxygen as a function of altitude.
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From page 242... ...
242 = x J°,,.I Liz En,_ In ° Lo I ~ ~ ~n O> ~ ' ~Z z o LlJ o Z ~ O -~ ~ ~ ~: O JO cn ~ ~ ~D ct= CE )
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From page 243... ...
are useful for testing hypotheses in the chemical reaction schemes used in the stratospheric models. We adopt here an approach that closely parallels that taken by the WMO/NASA review committee on trace species: Only those data on NO will be accepted that have been obtained by research groups who have repeatedly applied the method and have done the laboratory calibration tests required for a defensible absolute calibration.
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From page 244... ...
Several techniques have contributed significantly to the in situ data base: balloon-borne chemiluminescence (Ridley and Howlett 1974, Drummond et al. 1977, and an extensive series of reports by Ridley and co-workers)
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From page 245... ...
What can be concluded, however, is that very significant progress has been made in the analytical area: highquality in situ observations of NO are technically feasible. It will become apparent when attempting to use these data, that differences between profiles of a factor of 2 are of considerable importance when applying the NO results to modeled distributions.
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From page 246... ...
· ·o · ~ 1 38 109 K: ,0 [NO] [cm33 FIGURE D.25 Nitric oxide data of Figure D.24 converted to absolute concentration.
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L MIXING RATIO (PPBV) 10 FIGURE D.26 In situ NO mixing ratio measurements reported by four research groups, which encompass the stratosphere and mesosphere.
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248 ~ o \ NO| 0t ~ HO4OH it, hi' \ (CIONO) Go ~ ,h~ NO2 \ on FIGURE D.27 Partitioning of the reactive nitrogen family.
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From page 249... ...
. What these diurnal data do make clear is that the rapid fall off of NO at sunset obviates the possibility of using long-path absorption techniques for detailed measurements of nitric oxide.
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From page 250... ...
· ~ . L I I I I I I I0 0 40 80 120 160 200 240 280 320360 DAY NUMBER L I I I I I I I I I I I I J F M A M J J A S O N D MONTH FIGURE D.30 Nitric oxide seasonal data (122°W, 40°N)
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From page 251... ...
An inspection of Figure C.6a in Appendix C reveals that the NOX catalytic cycle NO + O3 ~ NO2 + O2 NO2 + O ~ NO + O2 0 + O3 ~ O2 + O2 constitutes 60 to 70 percent of the total loss rate for odd oxygen between 20 and 35 km. We are thus particularly interested in the NO2 data base as a test of ozone destruction rates.
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From page 252... ...
We would expect these results to be about 20 to 25 percent below the sunset data, all other things being equal, because of the diurnal behavior of NO2. Figure D.32 presents the mixing ratio data, a figure identical to that which appears in the WMO/NASA report with the pressuremodulated radiometer data added, and Figure D.33 presents the same set of data expressed in terms of absolute concentrations in an expanded abscissa.
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From page 253... ...
1978 O 10 OCTOBER 1979 IR ABSORPTION BLATHERWICK et al. 1980 O 9 FEBRUARY 1979 5 MAY 1979 VISIBLE ABSORPT ION F I SC H ER 1980 1 :-10 10 9 10-8 10-7 NO2 MIXING RATIO FIGURE D.32 Summary of sunset mid-latitude NO2 data between 20 and 40 km.
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From page 254... ...
The most obvious feature extracted from a comparison of Figures D.30 and D.32 is that there is an indication of larger mixing ratios of NO2 at high latitude in the altitude region between 20 and 30 km where the concentration of nitrogen dioxide peaks. The difference between 32°N and 51° to 58°N corresponds to a 50 percent increase in mixing ratio over this latitude range.
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- I ·KERR AND McELROY (1976) _ 22 JULY 1974 58°N · EVANS et oL 1978 _ 10 AUG 75 7 AUG 7551°N 19 AUG 75 28 AU G 76 ~ VISIBLE ABSORPTION , 1 1 1 1 Il111 1 1 1 1 1111 FIGURE D.34 NO2 sunset 45°-50°N (lower scale)
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From page 256... ...
1981) , and one used balloonborne visible absorption (Evans et al.
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From page 257... ...
53°N ·` _ · _ 1 49°N · .` . · 1974 · 1975 1976 · 1977 ,~_l, 1 J J A S O N D J F M A M J J J J A S O N D J F M A M J J FIGURE D.35 Seasonal variation of late afternoon NO2 at four latitudes, as given by the ground-based visible absorption spectroscopic measurements of Noxon (1979~.
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From page 258... ...
1981~. 48 `3~ 38 25 LL I 28 15 18 i: ll Mean and Range of 4 Flights for Nitrogen Dioxide 18-1 1 August 1975 17-18 August 1975 19-28 August 1976 28-29 August 1976 Yorkton' Saskatchewan Sunrise /~ NON, 8.1 1.8 1 8.8 VOLUME MIXING RATIO (ppbv)
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From page 259... ...
This figure is not inconsistent with the only other data available, that of Noxon, who estimates, based on ground-based visible absorption data, a column density of 1014 cm~2 in the spring and an upper limit in the summer of 4 x 1013 cm~2. While it may well turn out to be irrelevant due to the very different moisture level, total pressure, and heterogeneity of the troposphere, it should be noted that NO3 currently represents an enigma to tropospheric NOX studies in that dramatically less NO3 is observed (when simultaneous NO2 measurements are made)
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From page 260... ...
260 12.0 10.0 8.0 G.0 NO^ o 4.0 2.0 Summer - ~ ~ W~1~ ~ O 03# 0 10 20 30 40 50 60 LATITUDE rN) FIGURE D.39 LaUtudinal and scasona1 v~iadons of ~e bte aDernoon ~rOcd column of NO~ , as measured by ~hUn and co-wo~ers using ~rcrahtorne in~ared absorption tech~ques (CoD>y et ~.1981~.
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From page 261... ...
Thus, although it has been searched for in the IR absorption data, there are no reported observations, and the upper limits one would extract from the data are incapable of testing our understanding of hydrogennitrogen oxygen photochemistry. Nitric Acid (HONO2)
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From page 262... ...
We present both the mixing ratio data in Figure D.42 (which is identical to the figure appearing in the WMO/NASA report) and the absolute concentration data in Figure D.43, the latter with an expanded abscissa (a format required for a detailed comparison with modeled distributions, as we will see in the sections that follow)
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From page 263... ...
I ~ `, O Spring 1971 I I I, O Spring 1972 32°N I 1 i 20 - OSpring 1973 1 ~i_ 15 _ ~1__ 10 I -- ~: - T~ ::~S ~,~ 0.1 _ A _ i ~ HI_ ~ MIDLAT ITUDES ~ L_ _ r ~ ~ I ,NORTH 1~ 11 l ~ ~ VERTICAL COLUMNI l _ j ~ j5 -2 I ~ IlQ=+^nN 1n rm j 2 _ 10 1 1 1i~ ,.IiL.~1 l l l l l ~' - 1' MIXINC RATIO (ppbv) FIGURE D.42 In situ and remote measurements of the HNO3 mixing ratio at northern mid-latitudes.
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From page 264... ...
FIGURE D.44 Evidence for the lack of a seasonal variation in the vertical column density of HNO3 at latitudes less than 40°N, as measured by Coffey et al.
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From page 265... ...
Group 5: Reactive Trace Constituents Containing Bromine The Bromine Monoxide Radical (BrO) There are no reported observations of BrO in the stratosphere.
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From page 266... ...
Bromine Nitrate (BrONO2) There are no reported observations of BrONO2 in the stratosphere Group 6: Reactive Trace Constituents Containing Fluorine Fluorine Monoxide (FO)
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From page 267... ...
Hydrogen Fluoride (HF) Hydrogen fluoride has received considerable attention both because it possesses a strong IR absorption spectrum in the middle infrared and because it provides a very important check on the amount of fluorine released from the chlorofluorocarbons.
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From page 268... ...
268 oo _~ Ct C)
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From page 269... ...
11~ ~ =~11~1 -- MA ~ ~ ~ ~ HOW WELL DOES THE CURRENT DATA BASE ON STRATOSPHERIC REACTIVE TRACE SPECIES CONSTRAIN MODEL PREDICTIONS OF OZONE REDUCTION LEVELS? Progressing beyond the demonstration that the basic tenets of a given ozone reduction theory have a reasonably high probability of being qualitatively correct requires a significant advance in both the quality of the data available and the manner in which those data are employed.
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From page 270... ...
lo ~1 4 S 6 i8910 1 9 HF MIXING RATIO 1, i; i.: ~ ~ 1 ; 1 ., .
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From page 271... ...
whether that reaction set is complete with respect to those mechanisms that can directly affect odd oxygen. We will discover that the data currently available in large measure fail on both counts, but there are important exceptions.
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From page 272... ...
In order to correlate the rate constant data, the free radical concentration, and the resulting ozone reduction profiles, we define the following six model cases, which encompass the major uncertainties in laboratory rate data. Case 1: A set of rate constants identical to that recommended in Hudson and Reed (1979)
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From page 273... ...
273 ~ ~-o =:,rl I' .
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From page 275... ...
Profile Figure D.48 compares the model calculated [C10] profiles for each of the six cases defined above, with the corresponding altitude dependence of ozone reduction for steady state conditions given 1976 release rates of fluorocarbons and 1979 release rates for chloroform.
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From page 276... ...
276 I I f~ \ / / ct / / n oV / \: ~ 1: 1 1 41 C~ 1 1 o o o 1 1 o o N _ 1 1 1 1 1 1 _ - ~ ~ I3J L'J L1J ~n <: ~ ~ a ~, /r ~ // ~ // ~_ o _& O ,r, 0 ,n O [W\] ~anllllv - o aD - o ° tD 0 - o ~ ~° ~ ~ / // W// N r~ _ o o to a, rr)
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From page 277... ...
at 20 km. The isolation of chlorine-induced ozone destruction to the middle and upper stratosphere greatly simplifies the interpretation of ozone destruction by chlorine both because the chemical time constant for ozone (defined here as the ozone concentration divided by the rate of odd oxygen production)
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From page 278... ...
4YA\-iox'~2 W ~4~ o o· \ \ ~\~`ox lo, o · ' o oat/ ~ to no o , a° W~; ~ , CA5~:CASE 3//J~ MODEL CALCULATIONS, SEE TEXT FOR DE=ILS SAME REACTION SET USED IN 1979 ACADEMY REPORT: CASE 2 INCLUDES ALL NEW RATE CONSTANT MEASURE MENTS SINCE 1979 EXCEPT THOSE NOTES IN CASES 3-6 CASE 3 FAST OH+HONO2-H~O ~ NO CASE 4 FAST OH-HO2NO2-PROD CASE 5 fAST OH+Ho2-H2O ~ O2 CASE 6 SLOW ClO-NO2-C10NO2 IN SITU OBSERVATIONS .
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From page 279... ...
, but also because it seriously constrains any proposed mechanism involving chlorine radicals in the lower stratosphere. Such a proposed mechanism might involve either a catalytic cycle that is involved directly in the recombination of odd oxygen or a reaction linking the chlorine system to another family of reactants (e.g., bromine, nitrogen, hydrogen, etc.)
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From page 280... ...
' ' I 1, 1 I , 1 2 3 4 5 RATIO [ClO] oBsERvE;[c~qcA~cuLATED FIGURE D.52 Correlation between the model-calculated altitude dependence of ozone depletion (resulting from 1976/1979 release rates, as noted in the text)
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From page 281... ...
We can, of course, search elsewhere for clues regarding the destruction of OH in the lower stratosphere, most notably in the nitrogen system. Before doing this, however, we turn to a brief review of the nitrogen-catalyzed destruction of odd oxygen and the perturbation of O3 resulting from the doubling of N2O.
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From page 282... ...
282 501 1 1 ~ 1 1ii ~ CASE 5 ~ 45 40 ~, 35 _ c, 30 _ J 25 ~r 2O 1, ~ 1 ' 1 1.
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From page 283... ...
, approximately 70 percent of the total production rate of odd oxygen between 20 and 35 km is balanced by NOk catalysis (rate limited by NO2) for a reaction rate constant set corresponding to Case 5, so differences of even +50 percent are of major import.
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From page 284... ...
1974 9 FEBRUARY 1977 VISIBLE ABSORPTION GOLDMAN et o,.
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From page 285... ...
This has been a persistent and unresolved feature and while the nitric acid data above 25 km are not as direct a check on the odd oxygen budget as are observations of NO and NO2, such differences are very clearly of concern. The Profile of the Ratio of [O(3P)
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From page 287... ...
(cm~3) In situ Results Remote Results Lazrus and Gandrud (1974)
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From page 288... ...
reveals that, while the total number of observations has not expanded dramatically in the past two years, the number of independent techniques has, in several key instances, brought much more clearly into focus a number of important questions. Those questions range from the more qualitative issues such as "typical" atmospheric variability of trace species (e.g., the newest generation of (six)
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From page 289... ...
Of perhaps greater importance was that a plausible mechanism for the cause of the discrepancy evolved out of laboratory measurements of the reaction rate constant data for OH + HONC2 and OH + HO2NO2, as noted in the definition of Cases 3 and 4. Without a resolution to Question 1, there will remain two schools of thought on quantitative predictions of fluorocarbon-induced ozone reduction, because the latter is a sensitive function of the vertical distribution of the rate limiting radical, C10, in the chlorine-catalyzed destruction of ozone.
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From page 290... ...
45 4n 3c Lid 3C 25 20 .
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From page 291... ...
It is important to note that all the measurement techniques provide data that are easiest to interpret in the low-pressure region of the upper stratosphere, so that if the middle and lower stratospheric profiles are correct, the probability is large that the high-altitude end of the profile is correct. Second, the development of ground-based mm-wave emission techniques provides the means for obtaining much better temporal coverage to search for the occurrence of enhancements reported by the in situ methods -- the only impediment currently preventing the initiation of that coverage is the serious attenuation of 204-GHz radiation by water vapor in the troposphere, which maximizes during the summer months, encompassing July when both high values were observed.
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From page 292... ...
accuracy of +10 percent throughout the day at equatorial, lower mid-latitude, and upper mid-latitude locations? Given our current picture of odd oxygen destruction rates, as summarized in Figure C.6a of Appendix C, catalytic destruction of odd oxygen by NOk constitutes at least 70 percent of the ozone budget between the tropopause and 35 km.
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From page 293... ...
Those in situ methods may well yield the first "cause and effect" studies of the odd oxygen budget by correlating local fluctuations in NO2 and O3 in the middle stratosphere, where the loss rate of O3 is controlled almost entirely by the NOx catalytic cycle. The infrared methods that are not plagued by the restriction of sunset-sunrise geometries may also, if cross-calibrated in the same air mass, yield important results that will address Question 3.
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From page 294... ...
Although high-quality profiles of the major radicals at midday are of first-order importance, there is a great deal to be learned from the temporal behavior, under carefully controlled conditions, of the highly reactive trace species following sunrise and sunset. It is crucial in these studies to achieve altitude resolution of 1 to 2 km and to watch several related species simultaneously.
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From page 295... ...
Simultaneous in situ observations of ozone may yield exceedingly important insight into the odd oxygen budget from the same series of observations.
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From page 296... ...
They present a particularly difficult analytical problem, however, because they are in general large polyatomic molecules that do not possess strong electronic transitions, yet their predicted concentrations fall below the detection threshold of long-path IR absorption techniques. PROSPECTS: The first three molecules in this group constitute an exceedingly difficult triplet from the point of view of analytical techniques that can be applied to the stratosphere.
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From page 297... ...
QUESTION 11: Does the odd oxygen production/destruction budget balance, based on observed concentrations of the rate limiting free radicals? Although transport times in the odd oxygen continuity equation obviate the possibility of applying a purely chemical test to the balance of local odd oxygen produc
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From page 298... ...
, and Or to Quantify, as a function of altitude and latitude, the balance between production and destruction of odd oxygen. Although this approach cannot directly test cause-and-effect relationships with the odd oxygen budget and the approach is currently seriously diluted by large experimental uncertainties, it must be carefully pursued.
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From page 299... ...
Simultaneous mixing ratio profiles of stratospheric NO and NO2 a s derived from balloon-borne infrared solar spectra. Geophysical Research Letters 7:471-473.
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From page 300... ...
Geophysical Research Letters 7:704. Coffey, M.T., W.G.
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From page 301... ...
Nitric oxide mixing ratios near the stratopause measured by a rocket-born e chemiluminescent detector. Geophysical Research Letters 5:1023-1026.
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From page 302... ...
Ground-based spectroscopic measurements of HC1. Geophysical Research Letters 7:869.
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From page 303... ...
Geophysical Research Letters 6:151. Menzies, R.T., C.W.
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From page 304... ...
Spectroscopic measurements of stratospheric nitric oxide and water vapor. Science -.
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From page 305... ...
Concentration of carbon monoxide in the upper stratosphere. Geophysical Research Letters 8(4)
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