OZONE CHEMISTRY AND TECHNOLOGY

Vertical Atmospheric Ozone Distributions H. K. PAETZOLD

Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 29, 2018 | https://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch033

Max

Planck Institute, Weissenau

bei Ravensburg, Germany

The observations reported make it possible to identify air masses of different origin in the stratosphere a n d to prove very slight vertical movements of the atmosphere by means of the ozone variation. Thereby a useful factor has been obtained for investigation of general atmospheric circulation a n d perhaps also for weather forecasting. During the International Geophysical Year the institute at Weissenau is carrying out observations of the vertical ozone distribution in polar, mean, and equatorial latitudes with the recently developed ozone radio sonde to gain a wider range of information on interdiurnal, meridional, a n d seasonal fluctuations of the vertical ozone distribution.

In recent y e a r s k n o w l e d g e of t h e v a r i a t i o n s of t h e v e r t i c a l ozone d i s t r i b u t i o n a t least for m e a n latitudes has been considerably widened, especially b y using balloon-borne u l t r a v i o l e t s p e c t r o g r a p h s , a n d t h e i m p o r t a n c e of these v a r i a t i o n s f o r t h e a n a l y s i s of mass t r a n s f e r processes i n t h e a t m o s p h e r e (H, 17) c a n a l r e a d y be seen. B e l o w a n a l t i t u d e of 35 k m . , ozone is a q u a s i c o n s e r v a t i v e e l e m e n t of t h e a i r , because t h e t i m e i n w h i c h t h e p h o t o c h e m i c a l e q u i l i b r i u m is r e - e s t a b l i s h e d a m o u n t s a t 30 k m . of a l t i t u d e t o 10 d a y s , a t 2 5 k m . t o 100 d a y s , a n d a t 20 k m . t o 1 y e a r . U p t o t h e p r e s e n t t i m e , t h e a v e r a g e h e i g h t of t h e b a l l o o n ascents w a s a b o u t 33 k m . , b u t i n M a y 1956 a t W e i s s e n a u a n a l t i t u d e of 44 t o 4 5 k m . w a s r e a c h e d f o r t h e first t i m e . W i t h t h e s p e c t r o g r a p h e m p l o y e d , t h e s p e c t r u m a t t h i s a l t i t u d e extends d o w n t o 2700 A . I t is s o m e w h a t a s t o n i s h i n g t h a t n o r a d i a t i o n c o u l d be o b s e r v e d i n t h e o z o n e - o x y g e n w i n d o w a t 2150 A . F i g u r e 1 shows t h e ascent c u r v e o b t a i n e d b y o p t i c a l a n d b a r o m e t r i c o b s e r v a t i o n . T h u s , a l t i t u d e s c a n n o w be r e a c h e d a t w h i c h t h e v e r t i c a l ozone d i s t r i b u t i o n s t i l l shows c o n s i d e r a b l e v a r i a t i o n s , as h a s a l r e a d y b e e n d e t e r m i n e d b y r o c k e t ascents a n d d u r i n g eclipses of t h e m o o n (13). A c o n t i n u o u s s t u d y of these v a r i a t i o n s a p p e a r s of i m p o r t a n c e because a possible d i r e c t influence b y v a r i a b l e u l t r a v i o l e t r a d i a t i o n of t h e s u n a t t h i s a l t i t u d e o n t h e ozone l a y e r a n d t h e r e b y o n t h e l o w e r a t m o s p h e r e w o u l d be r e a d i l y a p p a r e n t . Instruments Balloon-Borne Ultraviolet Spectrographs. B y using the spectrograph, from the s p e c t r a l i n t e n s i t y d i s t r i b u t i o n / ( λ , h) i n t h e u l t r a v i o l e t r e g i o n of t h e s o l a r s p e c t r u m , t h e ozone a m o u n t , x(h), a t a h e i g h t h a b o v e t h e i n s t r u m e n t w a s d e t e r m i n e d . A s t h e ozone c o n c e n t r a t i o n e(h)

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x(h), x(h) m u s t be d e t e r m i n e d w i t h i n 1 t o 2 % . 209

OZONE CHEMISTRY AND TECHNOLOGY Advances in Chemistry; American Chemical Society: Washington, DC, 1959.

A D V A N C E S IN CHEMISTRY SERIES

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Figure 1. Time-altitude curve for the balloon ascent on M a y 30, 1956 (7-kg. Darex balloon, 3-kg. spectrograph) B e c a u s e of t h e o v e r l a p p i n g F r a u n h o f e r l i n e s i n t h e u l t r a v i o l e t s o l a r s p e c t r u m , t h e e x a c t d i s t r i b u t i o n of t h e s p e c t r a l i n t e n s i t y I ( λ , h) i s also a f u n c t i o n of t h e o p t i c a l q u a l i t i e s of t h e s p e c t r o g r a p h itself. T h e shape of a s p e c t r a l l i n e is s t r o n g l y i n f l u e n c e d b y t h e w i d t h of t h e slit a n d t h e s p e c t r a l d i s p e r s i o n of t h e i n s t r u m e n t , t h e degree of u n i f o r m i t y of t h e l i g h t i l l u m i n a t i n g t h e s l i t , a n d t h e c h a r a c t e r i s t i c s a n d p r o c e s s i n g of t h e p h o t o g r a p h i c p l a t e a n d i t s p o s i t i o n r e l a t i v e t o t h e f o c a l p l a n e . / ( λ , h) w i l l t h e r e f o r e differ s o m e w h a t f o r s p e c t r o g r a p h s of v a r i o u s c o n s t r u c t i o n s . I n order t o o b t a i n a homogeneous observation m a t e r i a l , the spectrographs should be o f a s t a n d a r d t y p e w h i c h r e m a i n s o p t i c a l l y c o n s t a n t d u r i n g flight ( t e m p e r a t u r e , e t c . ) . T h e a u t h o r h a s d e v e l o p e d a v e r y s t a b l e a n d also v e r y l i g h t s p e c t r o g r a p h (6, H). T h e o p t i c s , b a r o g r a p h , a n d t h e r m o g r a p h a r e m o u n t e d i n a closed m e t a l case. T h e a p p a r a t u s p r o v e d t o b e so s t a b l e t h a t e v e n a f t e r r o u g h l a n d i n g s i t n e e d e d n o readjustment. T h e p h o t o m e t r i c e v a l u a t i o n of t h e s p e c t r a h a s t o be c a r r i e d o u t v e r y c a r e f u l l y . T h e t r a n s m i t t a n c e of t h e three-stage filter e m p l o y e d i n f r o n t of t h e s l i t w a s c a l i b r a t e d b y m e a n s o f a p h y s i c a l m e t h o d ( F r a u n h o f e r d i f f r a c t i o n ) (11, 12). A s p e c i a l p r o c e d u r e w a s u s e d f o r c h e c k i n g t h e p a t h of t h e t h r e e i n t e n s i t y c u r v e s of t h e s p e c t r u m (6). A s a r e s u l t of a l l these p r e c a u t i o n s , a n a c c u r a c y t o 1.5% f o r a single m e a s u r e m e n t of x(h) w a s o b t a i n e d . T h e e r r o r s i n e(h) t h e n a m o u n t t o ± 1 , 0.5, a n d 0.3 X 1 0 ~ c m . of ozone p e r k m . f o r a l t i t u d e s of 5, 2 5 , a n d 30 k m . , r e s p e c t i v e l y . Ozone R a d i o Sonde. C o n s i d e r i n g t h e s t r o n g fluctuations of t h e v e r t i c a l ozone d i s t r i b u t i o n a n ozone r a d i o sonde w a s d e v e l o p e d w h i c h w o r k s s i m p l y a n d s u p p l i e s t h e c a l i b r a t i o n r e q u i r e d f o r h o m o g e n e o u s o b s e r v a t i o n m a t e r i a l (3, 4)· T h e r a d i o sonde i n c o r p o r a t e s t h e use of filters f o r t h e u l t r a v i o l e t region as i n p r e v i o u s c o n s t r u c t i o n s (1, 19), a n d of a s e l e n i u m p h o t o e l e m e n t . T h e light currents are amplified b y a threestage a m p l i f i e r a n d t h e i r i n t e n s i t i e s a r e t r a n s m i t t e d t o t h e r e c e i v i n g g r o u n d s t a t i o n b y a n a m m e t e r a n d a r o t a t i n g M o r s e c y l i n d e r . T h i s o p t i c a l m e t h o d seemed t o b e t h e m o s t s u i t a b l e f o r a n ozone s o n d e w h i c h w i l l be u s e d a t v a r i o u s s t a t i o n s w h e r e n o specialists are available. I f t h e o p t i c a l ozone sonde is t o w o r k w e l l , t h e s u n l i g h t m u s t be d i v i d e d i n a s u i t a b l e w a y i n t o t w o s e p a r a t e d s p e c t r a l regions : one r e g i o n i n f l u e n c e d b y ozone ( u l t r a v i o l e t l i g h t ) a n d one n o t i n f l u e n c e d b y ozone ( b l u e l i g h t ) . T o o b t a i n sufficient m e a s u r i n g p r e c i s i o n w i t h a s i m p l e i n s t r u m e n t , t h e ozone r e a d i n g m u s t r e s u l t f r o m t h e q u o t i e n t , u l t r a 3



PAETZOLD—VERTICAL

211

ATMOSPHERIC DISTRIBUTIONS

v i o l e t l i g h t / b l u e l i g h t . T h i s m e a n s t h a t t h e t w o s p e c t r a l regions m u s t n o t o v e r l a p e a c h o t h e r c o n t r a r y t o t h e p r e v i o u s l y d e v e l o p e d ozone sondes. S o m e filters n o w a v a i l a b l e are a c c e p t a b l e f o r t h e u l t r a v i o l e t l i g h t r a n g e b e l o w 3250 Α . , w h i c h i s affected b y ozone. T h e y a r e of sufficient c o n s t a n c y a n d t r a n s m i t t a n c e ( c o l o r a n d i n t e r f e r e n c e filters). A s regards t h e s p e c t r a l t r a n s m i t t a n c e c u r v e , t h e r e i s a n o p t i m u m i n t h e r e g i o n o f 3 1 0 0 A . of t h e degree of ozone a b s o r p t i o n a n d s u n l i g h t i n t e n s i t y . F i g u r e 2 shows v a r i o u s filters f o r u l t r a v i o l e t l i g h t . T h e f o r m e r c o l o r filter G G 19 m a d e b y S c h o t t i s v e r y g o o d . U n f o r t u n a t e l y , f o r t h e first sondes o n l y filter G G 1 9 + w a s a v a i l a b l e , w i t h a transmittance m a x i m u m a t a wave length somewhat too long f o r t h e desired purposes. R e c e n t l y a n i n t e r f e r e n c e edge filter h a s b e e n d e v e l o p e d ( S c h o t t , M a i n z ) s h o w i n g a v e r y h i g h t r a n s m i t t a n c e m a x i m u m a n d a v e r y a b r u p t descent a t l o n g e r w a v e l e n g t h s ( F i g u r e 2, N o . 4 ) . I n t h e f u t u r e t h i s filter w i l l b e u s e d . T h e b l u e l i g h t i s i s o l a t e d b y c o m b i n a t i o n o f filters U G 11 a n d W G 1 w i t h a t r a n s m i t t a n c e m a x i m u m a t 3700 A . T h e selenium photoelement w i t h a quartz layer is constant a n d l o w priced. I n Τ

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Some optic filters in the ultraviolet region

1. Schott filter G G 19+ 2. 3. 4. 5.

Interference Schott filter Interference Interference

filter with a 200-A. half width G G 19 edge filter filter with a lOO-A. half width

the spectral region used f o r t h e measurements, i t s sensitivity varies o n l y v e r y little as c o m p a r e d t o p h o t o c e l l s w i t h m e t a l l a y e r s , w h e r e s e l e c t i v i t y enters c o n s i d e r a b l y i n t o t h e m e a s u r e m e n t s . A b o v e t h e p h o t o e l e m e n t t h e r e is a q u a r t z s p h e r e , t h e i n s i d e of w h i c h is covered w i t h a magnesium oxide layer, t o render t h e i l l u m i n a t i o n of t h e cell i n d e p e n d e n t of t h e s u n ' s a n g l e of i n c i d e n c e . T h e light falling o n t h e photoelement is extinguished b y a rotating dial a t a fre q u e n c y o f 5 0 s e c - . T h e p h o t o c u r r e n t s a r e a m p l i f i e d 1000 t i m e s b y t h e t h r e e - s t a g e R C a m p l i f i e r . F o r c h e c k i n g t h e a m p l i f i e r , a d i r e c t v o l t a g e i m p u l s e ( 6 0 0 s e c . ) is a m p l i f i e d a t t h e same t i m e . T h e i m p u l s e g e n e r a t o r consists o f a R e i n a r t z c i r c u i t (0.2 w a t t ) w i t h a f r e q u e n c y of 152 m e g a h e r t z e s . F i g u r e 3 shtfws t h e b l o c k d i a g r a m o f t h e sondé. T h e filters a r e m o u n t e d o n a d i s k w h i c h r o t a t e s step b y s t e p a n d closes t h e e l e c t r i c c i r c u i t s r e q u i r e d f o r t h e v a r i o u s m e a s u r e m e n t s . T h e sequence o f t h e a u t o m a t i c m e a s u r e m e n t s of t h e s o n d e i s ; 1

- 1

1. I n t e n s i t y of u l t r a v i o l e t l i g h t influenced b y ozone 2. I n t e n s i t y of blue l i g h t n o t influenced b y osône 3. Pressure



212


MORSE CYLINDER

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CONTROL

Z E R O POINT OR TEMPERATURE RELATIVE HUMIDITY

Figure 3.

Block diagram of ozone radio sonde

4. Control voltage for checking the amplifier 5. Temperature (may be measured by a Wollaston wire not influenced by radiation) A s o n e s u c h c y c l e lasts 2 0 seconds, a n ozone m e a s u r e m e n t t a k e s p l a c e e v e r y 2 0 0 m e t e r s . T h e sonde weighs 4 k g . a n d reaches a n a l t i t u d e of 2 8 t o 3 0 k m . w i t h a 2 - k g . neoprene balloon. I n o r d e r t o c h e c k t h e c a l i b r a t i o n of t h e ozone sonde, s e v e r a l ascents w e r e m a d e w i t h b o t h t h e s o n d e a n d u l t r a v i o l e t s p e c t r o g r a p h . F i g u r e 4 gives t h e single m e a s u r e m e n t s of u l t r a v i o l e t l i g h t , e t c . , f o r one ascent. I n F i g u r e 5 t h e r e s u l t s o b t a i n e d b y m e a n s of t h e sonde a n d t h e s p e c t r o g r a p h a r e c o m p a r e d a n d f o u n d t o agree s u f f i c i e n t l y . T h e s e m e a s u r e m e n t s w e r e m a d e w i t h t h e i n f e r i o r u l t r a v i o l e t filter G G 1 9 + ( F i g u r e Ο

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213


PAETZOLD—VERTICAL ATMOSPHERIC DISTRIBUTIONS

2) a n d t h e e r r o r a m o u n t s t o 2 0 % of e(h) f o r a n a l t i t u d e of 2 5 k m . T h e i n t e r f e r e n c e edge f i l t e r ( F i g u r e 2, N o . 4 ) reduces t h i s e r r o r t o a b o u t 3 % ; t h u s t h e sonde w o r k as w e l l as t h e u l t r a v i o l e t s p e c t r o g r a p h , as recent s o u n d i n g ascents h a v e s h o w n . Variations of O b s e r v e d Vertical

Ozone

Distributions

S e a s o n a l V a r i a t i o n s . F i g u r e 6 s u r v e y s t h e i n t e g r a l c u r v e s x(h) f o r v a r i o u s seasons as o b t a i n e d a t W e i s s e n a u ( 4 8 ° N ) (9). T h e ozone a m o u n t b e t w e e n 0 a n d 20 k m . shows p a r t i c u l a r l y s t r o n g v a r i a t i o n s i n s p r i n g , because of t h e s t r o n g m e r i d i o n a l ozone g r a d i e n t a t t h i s a l t i t u d e . I n p o l a r zones t h e r e i s m u c h ozone b e l o w 2 0 k m . i n 40i

X(H), CM 0

Figure 6.

X(H), CM 0

3

3

integral curves x(fi) observed by balloon ascents at Weissenau a. Summer and spring b. Autumn and winter


ADVANCES

214

IN CHEMISTRY SERIES

s p r i n g a n d s u m m e r , w h i l e a t l o w e r a l t i t u d e s o n l y v e r y l i t t l e ozone is f o u n d . Mean w h i l e recent d i r e c t m e a s u r e m e n t s w i t h t h e r a d i o o z o n s o n d e m a d e b y t h e a u t h o r i n n o r t h e r n N o r w a y a n d e q u a t o r i a l A f r i c a c o n f i r m e d t h i s p i c t u r e of t h e m e r i d i o n a l v a r i a t i o n s of ozone g a i n e d p r e v i o u s l y b y i n d i r e c t m e t h o d s [ " U m k e h r " effect a n d m o o n eclipses (13)1. W h e t h e r o r n o t t h e a i r is r i c h i n ozone d e p e n d s o n w h e t h e r t h e a i r comes f r o m l o w e r o r h i g h e r l a t i t u d e s . I n a u t u m n these m e r i d i o n a l g r a d i e n t s a r e m u c h weaker.


T h e b a l l o o n ascents p e r m i t t e d , f o r t h e first t i m e , d e t e r m i n a t i o n o f t h e seasonal f l u c t u a t i o n s of t h e ozone c o n t e n t a t v a r i o u s h e i g h t s w h i c h p r o d u c e t h e seasonal changes of t h e t o t a l ozone a m o u n t , w i t h i t s k n o w n m a x i m u m i n s p r i n g i n m e a n a n d h i g h e r l a t i t u d e s . F i g u r e 7 shows t h a t t h e a n n u a l ozone course differs f o r t h e different

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Figure 7.

Annual variation of ozone amount at different altitudes at Weissenau


215


h e i g h t s . T h e s u m m e r m a x i m u m a b o v e 3 0 k m . is c a u s e d p h o t o c h e m i c a l l y ( l o w e r m e a n z e n i t h d i s t a n c e of t h e s u n ) a n d is c o n s i s t e n t w i t h t h e p h o t o c h e m i c a l t h e o r y . T h e s p r i n g m a x i m u m b e l o w 2 0 k m . i s m a i n l y caused b y o z o n e - r i c h a i r b r o u g h t d o w n f r o m polar latitudes. T h e s u m m e r m i n i m u m a t a n a l t i t u d e b e t w e e n 2 0 a n d 25 k m . is p r o b a b l y c a u s e d b y a h i g h e r r e a c h i n g t u r b u l e n c e w h i c h b r i n g s m o r e ozone d o w n t h a n c a n b e p r o d u c e d p h o t o c h e m i c a l l y . I t is s t r i k i n g t h a t b e t w e e n 25 a n d 30 k m . t h e r e is n o seasonal v a r i a t i o n . O b v i o u s l y photochemical a n d atmospheric factors have n o great influence i n this region o r t h e y compensate each other.


A p a r t f r o m these f a c t o r s t h e r e seems t o exist a n o t h e r i n f l u e n c e o n t h e a n n u a l fluctuations of t h e o z o n e ; t h i s f a c t o r c a n b e seen i n F i g u r e 8, w h i c h gives t h e m i x i n g

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OZONE/AIR Figure 8.

Ozone-air ratio for different seasons

r a t i o of ozone a n d a i r . T h e c u r v e s f o r J a n u a r y a r e 1 t o 2 k m . l o w e r t h a n those f o r O c t o b e r . L o w e r i n g of t h e s t r a t o s p h e r e w i t h a speed of 0.1 m m . p e r second causes b y c o n v e r g e n c e t h e n e w rise of t h e ozone i n N o v e m b e r , a c c o r d i n g t o t h e e q u a t i o n at

~ "

M

oh

~ pdtf ° V [

3

(

1

)

w h e r e [ 0 ] is t h e n u m b e r of ozone m o l e c u l e s p e r c u b i c c e n t i m e t e r , V is t h e v e r t i c a l s p e e d i n t h e a t m o s p h e r e , a n d is t h e a i r d e n s i t y . T h e l a s t effect shows t h e i m p o r t a n c e of t h e ozone v a r i a t i o n i n t h e a n a l y s i s of w o r l d wide circulations i n the atmosphere. Variations of Single Ozone Distributions. A c c o r d i n g t o t h e d i s p e r s i o n of t h e p o i n t s i n F i g u r e 7, single ozone d i s t r i b u t i o n s s h o w s t r o n g v a r i a t i o n s . T h e m o s t s t r i k i n g f a c t is t h a t t h e r e are d i s t r i b u t i o n c u r v e s w i t h s e v e r a l p e a k s ( F i g u r e 9 ) . W h i l e t h e p h o t o c h e m i c a l l y c a u s e d p r i m a r y m a x i m u m a t 2 3 k m . a l w a y s exists, t h e r e is a s e c o n d a r y n o n p e r m a n e n t m a x i m u m a t 15 k m . a n d a t e r t i a r y one a t 6 k m . Sometimes the m a x i m a are s h a r p l y separated f r o m each o t h e r ; sometimes they are smooth a n d m e r g e i n t o e a c h o t h e r . I n r a r e cases, t h e first m a x i m u m a t 23 k m . seems t o s p l i t u p i n t o t w o m a x i m a w i t h a d i s t a n c e i n a l t i t u d e of a b o u t 2 k m . A m o r e p e r f e c t e d o b s e r v a t i o n a l m e t h o d w i l l p r o b a b l y show still more details. H o w e v e r , the three m a x i m a mentioned h

3

p



216


Figure 9.

O z o n e distribution with several summer

peaks in spring

and

a. Air from subtropical latitudes b. Air from polar latitudes

are o f t e n v e r y d i s t i n c t a n d a r e a l w a y s a t t h e same a l t i t u d e s , so t h a t we c a n c o n s i d e r t h e m as one of t h e m a i n c h a r a c t e r i s t i c s of t h e ozone f l u c t u a t i o n s . T h e t e r t i a r y m a x i m u m lies b e t w e e n t h e e a r t h a n d t h e t r o p o p a u s e a n d t h e s e c o n d a r y b e t w e e n t h e t r o p o p a u s e a n d t h e w e l l - k n o w n zone of t h e m i n i m u m of t h e m e a n w i n d speed a t 20 k m . , i n w h i c h t h e change f r o m west t o east w i n d s o c c u r s i n s u m m e r also. T h e t e r t i a r y a n d s e c o n d a r y m a x i m a a r e p r o b a b l y caused b y h o r i z o n t a l t r a n s f e r s of a i r of different ozone c o n t e n t s (6). T h e s e c o n d a r y m a x i m u m a t a h e i g h t o f 16 k m . can v e r y clearly be a t t r i b u t e d to advection. T h e secondary m a x i m u m i n s p r i n g a n d s u m m e r w i l l a l w a y s o c c u r w h e n t h e a i r i n these a l t i t u d e s o r i g i n a t e s f r o m p o l a r regions. O n t h e o t h e r h a n d , t h i s m a x i m u m does n o t a p p e a r w h e n t h e a i r comes f r o m s u b t r o p i c a l regions. I n a u t u m n , h o w e v e r , t h e s e c o n d a r y m a x i m u m w a s n o t o b s e r v e d o r w a s v e r y w e a k , e v e n w h e n t h e a i r c a m e f r o m p o l a r regions (5, 9). T h i s corresponds t o t h e a b o v e - m e n t i o n e d v e r y s l i g h t m e r i d i o n a l g r a d i e n t of t h e ozone c o n t e n t a t t h i s season. I n F i g u r e 9,a, i t is s t r i k i n g t h a t v e r y l i t t l e ozone is f o u n d i n t h e r e g i o n b e t w e e n 8 a n d 16 k m . P r o b a b l y t h i s o z o n e - p o o r a i r s t r e a m s f r o m t h e t r o p i c a l l a t i t u d e s t o h i g h e r ones t h r o u g h t h e g a p b e t w e e n t h e t r o p i c a l a n d m e a n l a t i t u d e t r o p o p a u s e . I n a l l cases w h e r e t h e r e w a s a s e c o n d a r y ozone m a x i m u m a n a b r u p t change of t h e w i n d w a s o b s e r v e d a t t h e same h e i g h t . H o w e v e r , n o t a l l v a r i a t i o n s of t h e h o r i z o n t a l ozone d i s t r i b u t i o n c a n b e a t t r i b u t e d to a d v e c t i o n of a i r masses of different ozone c o n t e n t . I t is s t r i k i n g t h a t t h e p r i m a r y m a x i m u m changes i t s f o r m s o m e t i m e s : a t one t i m e i t i s s h a r p e r , a t a n o t h e r s m o o t h e r . T h i s effect c a n n o t b e c a u s e d b y changes of t h e p h o t o c h e m i c a l c o n d i t i o n s o r a d v e c t i o n . F i g u r e 10 gives ozone d i s t r i b u t i o n s w i t h s h a r p a n d s m o o t h m a x i m a m e a s u r e d d u r i n g one m o n t h i n a u t u m n i n w h i c h t h e a d v e c t i v e influence is s m a l l . I t c a n b e seen t h a t the f o r m of t h e c u r v e s f o r t h e r a t i o of ozone t o a i r i s t h e s a m e , e s p e c i a l l y f o r t h e t w o ascents t o h i g h e r a l t i t u d e s , b u t t h a t t h e y l i e a t different h e i g h t s . T h e s e d i f f e r ences m u s t be cause b y v e r t i c a l a i r m o t i o n s . I t i s s t r i k i n g t h a t t h e c u r v e s cross e a c h o t h e r a t a n a l t i t u d e of 20 k m . , w h i c h m e a n s t h a t a t t h i s a l t i t u d e t h e v e r t i c a l m o v e m e n t s change t h e i r signs. T h e speed of t h i s v e r t i c a l m o v e m e n t c a n b e e s t i m a t e d , f r o m the i n t e r v a l s b e t w e e n t h e ascents a n d f r o m t h e e s t a b l i s h m e n t of t h e p h o t o c h e m i c a l e q u i l i b r i u m , t o be a t least 1 t o 10 c m . p e r second. F o r t h e regions of t h e t e r t i a r y a n d s e c o n d a r y ozone m a x i m a , some ascents


217



s h o w e d v e r y s h o r t d e v i a t i o n o r r e g i o n a l l y r e s t r i c t e d v a r i a t i o n s . V e r y o f t e n t h e same d i s t r i b u t i o n s were d e t e r m i n e d f o r ascent a n d descent of t h e b a l l o o n , b u t i n some cases t h e r e are c l e a r differences. F i g u r e 11 gives a n i n s t r u c t i v e e x a m p l e . Because of t h e p o s i t i o n o n t h e c h a r t of t h e i n d i v i d u a l o b s e r v a t i o n s a n d t h e e s t i m a t e d e r r o r m a g n i t u d e , t h e differences b e t w e e n ascent a n d descent m u s t be c o n s i d e r e d as r e a l . As s h o w n i n F i g u r e 12, t h e t e r t i a r y a n d s e c o n d a r y m a x i m a h a v e b e e n d i s p l a c e d t o c o n t r a r y d i r e c t i o n s b e t w e e n ascent a n d descent. A s t u d y of F i g u r e 12 i n d i c a t e s t h a t t h i s v a r i a t i o n m u s t also be c a u s e d b y v e r t i c a l m o v e m e n t s . A t a n a l t i t u d e of 9 t o 10 k m . these m o v e m e n t s o b v i o u s l y change t h e i r signs. A t a n a l t i t u d e of 5 k m . t h e r e is a n u p w a r d speed of 10 c m . p e r s e c o n d a n d a t 15 k m . one of 10 c m . p e r second, w h i l e a t a l t i t u d e s of 9 a n d 24 k m . t h e v e r t i c a l m o v e m e n t s d i s a p p e a r . O n the basis of these o b s e r v e d v a r i a t i o n s i n t h e v e r t i c a l ozone d i s t r i b u t i o n i t is possible t o p r o v e d i r e c t l y t h e s o - c a l l e d " z e r o l a y e r " i n w h i c h t h e v e r t i c a l m o v e m e n t s o f t e n change 40

1—r~T~i ι 1111

1

r

1 1 1 1II /

/

I

/

J

30

2 Ï ©

20

111 X 10

L 0

0.01

OZONE

1

0.02

1 1 1 1 1 ll 10

1I 1 1 1 1 II 100

(OZONE/AIR)

CONCENTRATION CM 0

χ

I0~

7

3

KM

Figure

10.

Sharp and smooth primary ozone maxima during at Weissenau in autumn of 1953 1. 2. 3. 4.

ascents

September 8 September 28 October 23 October 28

t h e i r signs. A c c o r d i n g t o F i g u r e 10, a s e c o n d " z e r o l a y e r " seems t o exist i n a n a l t i t u d e of 20 k m . F r o m r e c e n t ozone s o u n d i n g s , a c o r r e l a t i o n c a n be f o u n d b e t w e e n t h e c i r c u l a t i o n i n the troposphere a n d stratosphere. So i n the statistical m e a n the g r o u n d a i r p r e s s u r e is l o w i f t h e f i r s t ozone m a x i m u m is s m o o t h a n d i t is h i g h i f t h e l a t t e r is s h a r p (7). O z o n e t h u s assists r e s e a r c h o n t h e d y n a m i c r e l a t i o n s b e t w e e n t h e t r o p o s p h e r e a n d the lower stratosphere. U p w a r d a n d d o w n w a r d m o v e m e n t s a l t e r t h e n u m b e r of ozone m o l e c u l e s i n t h e v o l u m e u n i t a c c o r d i n g t o E q u a t i o n 1. I t is seen a t once t h a t t h e r e is n o a l t e r a t i o n if O / is c o n s t a n t — t h a t i s , i f t h e ozone s h o w s t h e s a m e decrease w i t h h e i g h t as t h e d e n s i t y of t h e a t m o s p h e r e . T h i s is n e a r l y t h e case i n t h e r e g i o n b e t w e e n 25 a n d 35 k m . B e l o w 2 5 k m . , t h e r a t i o 0 / p is m e a n p r o p o r t i o n a l t o ~ to p . I n this r e g i o n t h e ozone a m o u n t is i n c r e a s e d b y a d o w n w a r d c u r r e n t , a n d v i c e v e r s a . s p

3

P

1

-

3

I f t h e v e r t i c a l ozone d i s t r i b u t i o n is l o w e r e d b e t w e e n 10 a n d 20 k m . b y 1 k m . , t h i s m e a n s — e . g . , f o r a u t u m n — a n i n c r e a s e i n t h e t o t a l t h i c k n e s s of t h e l a y e r of 0.013 c m . of ozone, a p p r o x i m a t e l y 6 % . T a b l e I shows t h e r a t i o a t different seasons. T h e last



218


10

20 H,

30

KM

Figure 11. Integral curve x(h) during ascent a n d descent of balloon at Weissenau on August 1, 1955

OZONE

Figure 12.

/AIR

Vertical distribution of ozone-air ratio for measurement in Figure 11


219


c o l u m n shows t h e o b s e r v e d m e a n i n t e r d i u r n a l fluctuations of t h e t o t a l ozone a m o u n t f o r c o m p a r i s o n (2). I n s p r i n g t h e fluctuations w i l l b e d u e 5 0 % t o a d v e c t i o n a n d 5 0 % to vertical movements. I n a u t u m n , h o w e v e r , v e r t i c a l m o v e m e n t s w i l l b e of m o s t i m p o r t a n c e . T h e d i u r n a l m e a n ozone v a r i a t i o n s g i v e n i n T a b l e I i n d i c a t e a T a b l e I.

Seasonal Variation in Vertical O z o n e Distribution in Stratosphere Vertical Displacement of Ozone Distribution, C m . O3


Raised by 1 K m . Season Jan. 1 April 1 July 1 Oct. 1

Between 10 and 15 km. -0.004 -0.008 -0.007 -0.002

Lowered by 1 K m .

Between 10 and 20 km. - 0.014 - 0.016 -0.015 -0.009

Between 10 and 15 km. +0.007 +0.011 +0.009 +0.003

Between 10 and 20 km. +0.019 +0.021 +0.019 +0.013

Obsd. fluctuations ±0.014 ±0.012 ±0.005 ±0.007

m e a n a m p l i t u d e of u p w a r d a n d d o w n w a r d m o v e m e n t s of a b o u t 1 k m . b e t w e e n a l t i t u d e s of 10 a n d 20 k m . A f u r t h e r f a c t o r i n f l u e n c i n g t h e v e r t i c a l ozone d i s t r i b u t i o n i s t h e v e r t i c a l t u r b u l e n c e . T h i s i s , h o w e v e r , n o t t h e cause of f a s t fluctuations. I f , for instance, a con s i d e r a b l e change s h o u l d b e c a u s e d b y t u r b u l e n c e a t a n a l t i t u d e o f 3 0 k m . a g a i n s t t h e t e n d e n c y t o r e - e s t a b l i s h t h e p h o t o c h e m i c a l e q u i l i b r i u m , t h e exchange f a c t o r m u s t t e m p o r a r i l y s h o w a v a l u e of 0.1 t o 1 g r a m p e r c m . - s e c o n d , w h i c h w o u l d b e 10 t o 100 t i m e s larger t h a n the m e a n value at this altitude. Ozone

Balance

T h e v e r t i c a l t u r b u l e n c e , o n t h e o t h e r h a n d , h a s a c o n s i d e r a b l e influence o n t h e m e a n ozone d i s t r i b u t i o n b e l o w 2 0 k m . A c c o r d i n g t o t h e p h o t o c h e m i c a l t h e o r y , t h e r e s h o u l d b e n o ozone b e l o w 10 t o 15 k m . , because a t 5 k m . o n l y a b o u t o n e o z o n i z i n g l i g h t q u a n t u m p e r cc.-second is a b s o r b e d (8). A s c o s m i c r a d i a t i o n a n d e l e c t r i c discharges p r o d u c e f a r t o o l i t t l e ozone (6), t r o p o s p h e r i c ozone of t h e a m o u n t of 1 t o 4 Χ 1 0 c m . of ozone p e r k m . m u s t b e b r o u g h t d o w n f r o m t h e p h o t o c h e m i c a l l a y e r b y v e r t i c a l m i x i n g processes (16), w h e r e b y i t is c o n t i n u a l l y d e s t r o y e d o n t h e g r o u n d a n d i n l o w e r a i r l a y e r s . T h i s t u r b u l e n t ozone s t r e a m i s g i v e n b y -

3

(2)

where [M] is t h e n u m b e of a i r m o l e c u l e s p e r c c . A (h) i s t h e s o - c a l l e d " e x c h a n g e f a c t o r " N is A v o g a d r o ' s n u m b e r is t h e d e n s i t y of a i r ( S T P ) F r o m t h e o b s e r v e d m e a n t r o p o s p h e r i c ozone d i s t r i b u t i o n i t f o l l o w s t h a t (5, 6) A

p o

~ U3 = i . i u i

i

m

i i J

Q molecules τ sq. cm.-second 3

T h e same v a l u e f o r ozone d e s t r u c t i o n r e s u l t e d f r o m ozone fluctuations n e a r t h e g r o u n d (6, 18). O n t h e basis of t h e d e v i a t i o n s i n v e r t i c a l ozone d i s t r i b u t i o n f r o m t h e p h o t o c h e m i c a l l y c a l c u l a t e d d i s t r i b u t i o n t h e r e also results a v a l u e of 1 . 1 0 c m . of ozone p e r sq. c m . - s e c o n d f o r t h e c h e m i c a l r e g e n e r a t i o n (6). T h e r e f o r e , t h e ozone b a l a n c e seems to be m a i n t a i n e d . 11

A l l o v e r t h e w o r l d 1 0 m e t r i c t o n s of ozone p e r y e a r a r e d e s t r o y e d a n d p h o t o c h e m i c a l l y r e g e n e r a t e d . W i t h o u t t h e p h o t o c h e m i c a l r e g e n e r a t i o n , t h e ozone a m o u n t w o u l d decrease t o o n e t e n t h of i t s p r e s e n t v a l u e w i t h i n 3 y e a r s . A t m o s p h e r i c o x y g e n w i l l t h u s go t h r o u g h t h e o z o n i z e d state i n 1 0 y e a r s . T h i s f a c t shows t h e i m p o r t a n c e 9

6


220


which the ozone m a y have had i n the creation of the terrestrial atmosphere present state.

i n its


Conclusions T h e results of limited ozone measurements b y balloon ascents allow a far more detailed analysis of the factors influencing ozone distribution than the measurements of the total ozone amount made over many years at various locations b y the Dobson instrument. Some fundamental relations between ozone distribution and air movements have been obtained b y means of balloon ascents. T h e exact analysis of the fluctuations of total ozone amount, in conjunction with wind and temperature observations, permits something more definite to be said about ozone fluctuations at greater altitudes and the air movements connected with them. T h e course of the total ozone amount from February 27 to M a r c h 19 is a n example of this (IS). T h e strong influx of warm air on February 19 to 2 8 , 1956, into layers below 10 k m . caused a rapid decrease i n the ozone amount; accordingly, the warm air was of a subtropical character with little ozone. T h e increase on M a r c h 8 up to an amount of 0.335 cm. of ozone on M a r c h 12 coincided with a condition of mostly northern winds at all altitudes for several days. T h e increase was caused by the influx of air rich in ozone—that is, of polar air—below 20 k m . (secondary and tertiary maxima). When on M a r c h 12 the wind changed in the 100-mb region from N N E to W S W , the ozone amount began to decrease; this means that the secondary maximum was reduced b y the influence of subtropical air. This had been happening for 3 days before the tropospheric influx of warm air on M a r c h 15, by which the tropospheric ozone was also reduced. This example shows how changes of the ozone and thereby of the weather conditions make their way from higher to lower altitudes. A further striking fact is an abnormally quick increase on the morning of M a r c h 1, which can hardly be accounted for by advection only. Probably a strong local lowering of the atmosphere below 2 0 k m . was also influential.

Bibliography (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19)

Coblentz, W., Stair, R., J. Research Natl. Bur. Standards 22, 573 (1939). Götz, F. W. P., "Compendium of Meteorology," p. 275, Boston, 1950. Kulcke, W., Dissertation, Technische Hochschule, Stuttgart, 1956. Kulcke, W., Paetzold, H. K., Ann. Meteorol. 8, 47 (1957). Paetzold, H. K., Ibid., 8, 40 (1947). Paetzold, H. K., Habilitationsschrift TH. München, 1954. Paetzold, H. K., Intern. Union Geodesy and Geophysics, Toronto, 1957. Paetzold, H. K., J. Atm. and Terrest. Phys. 3, 125 (1953). Ibid., 7, 128 (1955). Paetzold, H. K., Naturwissenschaften 41, 320 (1954). Paetzold, H. K., Optik 6, 327 (1950). Paetzold, Η. Κ., Z. Naturforsch. 2a, 219 (1947). Ibid., 6a, 639 (1951); J. Atm. and Terrest. Phys. 2, 183 (1952). Paetzold, Η. Κ., Z. Naturforsch. 10a, 33 (1955). Paetzold, H. K., Zschörner, H . , Ann. Meteorol. 8, 54 (1957). Regener, V. H., Meteorol. Z. 60, 253 (1943). Regener, V. H., Nature 167, 276 (1951). Regener, V. H., Proc. Intern. Union Geodesy and Geophysics, Rome, 1954. Strantz, Ber. deut. Wetterdienst U. S. Zone No. 11, 44 (1949). RECEIVED for review M a y 17, 1957. Accepted June 19, 1957.


OZONE CHEMISTRY AND TECHNOLOGY

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