AERONOMICA ACTA

Texte intégral

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I N S T I T U T D ' A E R O N O M I E S P A T I A L E D E B E L G I Q U E

3 - Avenue Circulaire B - 1180 B R U X E L L E S

A E R O N O M I C A A C T A

A - N° 293 - 1984

Middel atmospheric NO and NC^observed by means of the Spacelab one grille spectrometer

by

J. LAURENT, M.-P. LEMAITRE, J. B E S S O N , A. GIRARD C. LIPPENS, C. MULLER, J. V E R C H E V A L and M. A C K E R M A N

B E L G I S C H I N S T I T U U T V O O R R U I M T E A E R O N O M I E 3 - R i n g l a a n

B - 1180 BRUSSEL

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F O R E W O R D

T h i s text will be p r e s e n t e d at the Fall Meeting of the American Geophysical Union (December 3 - 7 , 1984).

A V A N T - P R O P O S

Ce texte sera présenté à la, réunion d'automne de l ' A m e r i c a n Geophysical Union ( 3 - 7 décembre 1984).

V O O R W O O R D

Deze t e k s t zal v o o r g e s t e l d w o r d e n tijdens de h e r f s t - v e r g a d e r i n g v a n de American Geophysical Union ( 3 - 7 december 1984).

V O R W O R T

Dieser T e x t wird p r ä s e n t i e r t werden w ä h r e n d d e r H e r b s t - t a g u n g der American Geophysical Union ( 3 - 7 Dezember 1984).

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M I D D L E A T M O S P H E R I C N O A N D N 0o O B S E R V E D B Y M E A N S O F T H E S P A C E L A B O N E G R I L L E S P E C T R O M E T E R

b y

J. L A U R E N T * , M . - P . L E M A I T R E * , J. B E S S O N * , A . G I R A R D * C . L I P P E N S * * , C . M U L L E R * * , J. V E R C H E V A L * * a n d M. A C K E R M A N * *

*Office National d ' E t u d e s et de R e c h e r c h e s A é r o s p a t i a l e s , Châtillon, France.

* * Belgium Institute for S p a c e A e r o n o m y , B - 1180 B r u s s e l s , Belgium.

A b s t r a c t

D u r i n g the c o u r s e of the Spacelab O n e M i s s i o n in N o v e m b e r - December 1983 i n f r a r e d spectra of the earth atmospheric limb were obtained in a b s o r p t i o n u s i n g the setting a n d r i s i n g s u n as a s o u r c e . O n e r u n t a k i n g place in the s o u t h e r n hemisphere at s u n r i s e was dedicated to the simultaneous o b s e r v a t i o n of N O from 20 to 100 km altitude and of N 02 from 20 to 42 km altitude. T h e s t r a t o s p h e r i c profiles are in agreement with p r e v i o u s measurements. T h e m e s o s p h e r i c NO a b u n d a n c e e x h i b i t s a maximum near 90 km altitude a n d a minimum near 62 km altitude. T h e N O volume mixing ratio increases at least 1000 times from 60 to 100 km altitude where a value of 10 ^ is reached.

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Résumé

A u cours de la première mission de Spacelab en novembre- décembre 1983 des spectres d'absorption infrarouge du limbe atmo- sphérique furent obtenus en utilisant le soleil levant et couchant comme source. Une observation était consacrée dans l'hémisphère sud au lever à l'observation de NO de 20 à 100 km d'altitude et de N 02 de 20 à 42 km d'altitude. Les profils de concentrations stratosphériques obtenus sont en accord avec les résultats antérieurs. Le NO mésosphérique montre un maximum de concentration près de 90 km d'altitude et un minimum près de 62 km d'altitude. La concentration volumique de NO croît d'un facteur 1000 de 60 à 100 km où elle atteint 10~5.

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S a m e n v a t t i n g

T i j d e n s de e e r s t e v l u c h t v a n h e t Spacelab i n n o v e m b e r - d e c e m b e r 1983 w e r d e n i n f r a r o d e a b s o r p t i e s p e c t r a v a n de a t m o s f e r i s c h e

kim bekomen d o o r de zon b i j h a a r o p g a n g en o n d e r g a n g als b r o n t e g e b r u i k e n . Eén w a a r n e m i n g in de z u i d e l i j k e h e m i s f e e r b i j z o n s o p g a n g was g e w i j d aan de g e l i j k t i j d i g e w a a r n e m i n g v a n NO v a n 20 t o 100 km h o o g t e en v a n NO^ v a n 20 t o t 42 km h o o g t e . De bekomen p r o f i e l e n v a n s t r a t o s f e r i s c h e c o n c e n t r a t i e s stemmen o v e r e e n met v o o r g a a n d e r e s u l t a t e n . De m e s o s f e r i s c h e NO v e r t o o n t een m a x i m u m c o n c e n t r a t i e b i j 90 km h o o g t e en een minimum b i j 62 km h o o g t e . De v o l u m e c o n c e n t r a t i e v a n NO s t i j g t met een f a c t o r 1000 v a n 60 t o t 100 km h o o g t e waar een w a a r d e v a n 10 ^ b e r e i k t w o r d t .

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Z u s a m m e n f a s s u n g

W ä h r e n d des e r s t e n F l u g e s des S p a c e l a b s im N o v e m b e r - Dezember 1983 w u r d e n infraroten A b s o r p t i o n s p e k t r a d e r E r d e n r a n d e s bekommen mit d e r S o n n e bei ihren A u f g a n g u n d U n t e r g a n g als Quelle z u g e b r a u c h e n . Eine B e o b a c h t u n g in d e r s ü d l i c h e n Hemisphäre beim S o n n e n - a u f g a n g war v e r b u n d e n an d e r gleichzeitige B e o b a c h t u n g d e r N O v o n 20 bis 100 km Höhe u n d der N C ^ v o n 20 bis 42 km Höhe. Die bekommen Profilen v o n s t r a t o s p h ä r i s c h e r Konzentrationen stimmen ü b e r e i n mit v o r i g e n Resultaten. Das m e s o s p h ä r i s c h e NO zeigt eine Maximum- konzentration bei 90 km Höhe u n d ein Minimum bei 62 km Höhe. Die Volumenkonzentration v o n N O steigt mit einem Faktor 1000 v o n 60 bis 1ÜU km Höhe wo ein Wert v o n 10 e r r e i c h t w i r d .

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I N T R O D U C T I O N

A f t e r Nicolet (1945) s u g g e s t e d the p r e s e n c e of nitric oxide in the u p p e r atmosphere as a s o u r c e of the D region ionization b y the solar Lyman or radiation, it took almost 20 y e a r s untill t h i s trace species be o b s e r v e d ( B a r t h , 1964). T h i s was achieved t h r o u g h the r e s o n a n c e fluorescence method. Nearly 10 y e a r s later, the vertical d i s t r i b u t i o n of nitric oxide was o b s e r v e d in the s t r a t o s p h e r e b y means of balloon b o r n e i n f r a r e d a b s o r p t i o n spectrometry ( A c k e r m a n et a!., 1973).

Since then much emphasis has been put on odd n i t r o g e n compounds in the s t r a t o s p h e r e in relation with their role in controlling the o d d o x y g e n s t a t i o n n a r y a b u n d a n c e in the form of ozone. M a n y s t r a t o s p h e r i c measurements h a v e been performed of N O , N O £ , H N O ^ , NOg with inferences on the N2OJ. a b u n d a n c e . Meanwhile several d e - terminations of N O in the mesosphere and in the low t h e r m o s p h e r e h a v e been performed ( M e i r a , 1971; T i s o n e , 1973; Witt et a l . , 1976; T o h m a t s u a n d Iwagami, 1975; B a k e r et a l . , 1977 and T h o m a s , 1978) based on resonance fluorescence and b y means of mass spectrometers ( T r i n k s et a l . , 1978).

We wish to report here the f i r s t "one s h o t " o b s e r v a t i o n of N O from the low t h e r m o s p h e r e down to the low s t r a t o s p h e r e . T h i s was done b y means of a similar instrumentation as the one u s e d p r e v i o u s l y on board of balloon g o n d o l a s . T h i s time, h o w e v e r , the o b s e r v a t i o n platform being Spacelab one, the access to h i g h e r altitudes was p o s s i b l e . A s before ( A c k e r m a n et al, 1975) N O and N 02 were o b s e r v e d simultaneously.

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O B S E R V A T I O N

T h e i n f r a r e d grille spectrometer flown on b o a r d of the space shuttle d u r i n g the f i r s t Spacelab mission h a s already been d e s c r i b e d (Lemaitre et a l . , 1984). In the c o u r s e of this mission, one earth limb solar occultation r u n was devoted to the o b s e r v a t i o n of N O a n d N O? in the respective wavenumber r a n g e s : 1914.5 - 1918 cm a n d 1595 - 1598.5 cm . T h e c o r r e s p o n d i n g w a v e l e n g t h s were selected in the 6th and 5th o r d e r s of the g r a t i n g , as s h o w n in f i g u r e 1, b y two i n t e r - ference filters, one for each of the two liquid n i t r o g e n temperature cooled detectors.

T h i s o b s e r v a t i o n took place o v e r the s o u t h e r n Pacific ocean on December 1, 1983. T h e g e o g r a p h i c coordinates of the tangent p o i n t s of the solar r a y s reaching the i n s t r u m e n t to the geoTd's e n v e l o p p e s at 20 and 100 km altitude are s h o w n on f i g u r e 2. T h i s f i g u r e s h o w s the solar elevation angle v e r s u s time at the two g e o g r a p h i c locations. T h e o b s e r v a t i o n s took place at s u n r i s e after the v e r y s h o r t n i g h t s of the h i g h s o u t h e r n latitudes in the late fall. For the 20 km and TOO km tangent altitude locations, the s u n d e p r e s s i o n a n g l e s do not exceed 0 . 3 ° a n d 1 . 4 ° respectively in the c o u r s e of the d a y . T h u s the o b s e r v a t i o n s took place in nearly full d a y l i g h t conditions with practically all the o d d n i t r o g e n in the form of NO in the m e s o s p h e r e and in the form of N O , N 02 and H N 03 in the s t r a t o s p h e r e a c c o r d i n g to o u r p r e s e n t k n o w l e d g e of the atmospheric p h o t o c h e m i s t r y .

T h e spectra of which samples are s h o w n in f i g u r e s 3 a n d 4 for NO and N 02 were recorded e v e r y two s e c o n d s . T h e measured equivalent widths are s h o w n in f i g u r e s 5 a n d 6 v e r s u s tangent h e i g h t s in the atmosphere.

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WAVELENGTH ([im)

5 6

cr o

t-u <

^ 0.5

co

if) <

o:

GRATING

»

th

ORDER 5

t h

58.06 gr./mm 65.4°

0

-HH- NCX

1

F i g . 1 . -

2000 1800 1600 K 0 0

WAVENUMBER (cm"

1

)

T r a n s m i s s i o n factor v e r s u s wavenumber and w a v e l e n g t h of the i n t e r f e r e n c e f i l t e r s selecting the 5th and 6th o r d e r s of the g r a t i n g . T h e n a r r o w s p e c t r a l ranges used for the determination of NO and NOp are i l l u s t r a t e d .

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GMT

. 2 . - Solar elevation versus time in hours ( G . M . T . ) for December 1, 1983 and the geographic location of the tangent points at 20 and 100 km altitude of the solar rays to the inst-ument. The observation took place at sunrise from 9h03 min 38 sec to 9hr4 min 52 sec G . M . T . for the sun grazing altitudes from 20 to 100 km. T h e nearly whole day, full sunlight condition of the atmosphere is obvious.

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WAVENUMBER (cm"')

Fig. 3 . - Solar spectra recorded at sunlight tangent altitude equal to 86 km. Two NO absorption lines are indicated.

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1600 -

> £

LU

O 3

CL

<

1200

800

1596 1597

WAVENUMBER (cm"')

1598

Fig. 4 . - NC>2 absorption spectrum recorded at sunlight tangent altitude equal to 26 km.

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EQUIVALENT WIDTH (cm

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F i g . 5 . - Equivalent w i d t h s v e r s u s g r a z i n g s u n l i g h t altitude for the NO a b s o r p t i o n doublet at 1914.99 cm . - 1

T h e s q u a r e s r e p r e s e n t five kilometers a v e r a g e s .

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i i i i I I i | i i l l

£ 40 J*

LU 30 N 0 ? ^ ^

Q

L

Z) H- 1597.15 cm" 1

—I 20

< i i i i i i i i 1 -i i i 1

1 0 ~3 1 0 " 2

EQUIVALENT WIDTH (cm"')

Fig. 6 . - Equivalent width v e r s u s g r a z i n g s u n l i g h t altitude for the NOp multiplet center at 1597.15 c m "1.

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T h e i n v e r s i o n s of the data r e p r e s e n t e d b y the smooth c u r v e s in f i g u r e s 5 a n d 6 was made u s i n g the molecular line parameters of Rothman et al. ( 1 9 8 3 ) . T h e y lead to the vertical d i s t r i b u t i o n s of N O a n d N O ^ s h o w n in f i g u r e 7. A b o v e 98 km altitude, the s c a n n e d w a v e - length i n t e r v a l s were broadened in o r d e r to o b s e r v e b r o a d e r b a n d solar

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s p e c t r a . T h e 1914.99 cm N O line region was o b s e r v e d again at 105 km tangent altitude were the N O signal was to week to be detected. From 55 to 75 km altitude a d a s h e d line r e p r e s e n t s i n v e r t e d N O n u m b e r densities so low that the slant a b s o r p t i o n h a s to be attributed to N O at h i g h e r altitudes. Hence from 55 to 75 km altitude the N O a b u n d a n c e can only be tentatively g i v e n c o r r e s p o n d i n g more to a shallow u p p e r limit.

D I S C U S S I O N A N D C O N C L U S I O N

T h e s t r a t o s p h e r i c portion of the o b s e r v a t i o n may be characterized b y a h i g h signal to noise ratio for the a b s o r p t i o n lines.

Hence, the u n c e r t a i n t y on the volume concentrations is small a n d the v a l u e s are in the r a n g e of p r e v i o u s o b s e r v a t i o n s . T h e y will be d i s c u s s e d elsewhere.

For the sake of comparison with other o b s e r v a t i o n s in the mesosphere a n d in the low thermosphere the r e s u l t s are s h o w n in f i g u r e 8 with those p u b l i s h e d b y other a u t h o r s . T h e n i g h t N O ^ u p p e r a n d lower a b u n d a n c e s in the mesosphere o b s e r v e d b y means of the limb i n f r a r e d monitor of the s t r a t o s p h e r e ( L I M S ) on board of the Nimbus 7 satellite at h i g h n o r t h e r n latitude in winter are also s h o w n ( R u s s e l et al., 1984). T h e odd n i t r o g e n s h o u l d in this case be mostly in the form of NO£ p r o v i d i n g a source of data suitable for comparison with o u r s .

If o u r results show a rather good agreement with other o b s e r v a t i o n s at the h i g h e s t altitudes the differences become v e r y large at 85 km particularly with the vertical profiles e x h i b i t i n g a minimum

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NUMBER DENSITY (cm'

3

)

Fig. 7 . - Number densities of NO and NO? v e r s u s a l t i t u d e . T h e near s t r a i g h t

— - 1 0 - 5 lines indicate constant volume mixing ratios from 10 to 10 .

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10' iol

NUMBER DENSITY (cm"

3

)

Fig. 8.- Nitric oxide number densities presented in this paper with results of other authors. The meso- spheric NC>2 LIMS upper and lower values observed in December-January at high northern latitudes are also shown (see text).

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volume concentration at that altitude. T h e s h a p e of the vertical profile compares in the best f a s h i o n with the r e s u l t s of B a r t h (1964) a n d T i s o n e (1973). T h e N O ^ L I M S r e s u l t s tend to s u p p o r t o u r h i g h v a l u e s .

S l i g h t modifications of the new data p r e s e n t e d here may o c c u r if more refinement was to alter s i g n i f i c a n t l y the o r b i t parameters of the shuttle d u r i n g the f i r s t Spacelab mission. More o b s e r v a t i o n s will be possible when the i n s t r u m e n t will be flown in a mission more dedicated to atmospheric s t u d i e s . T h e y s h o u l d s h e d some usefull light on the p r e s e n t l y intricate picture of the mesospheric N O as illustrated in f i g u r e 8.

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R E F E R E N C E S

A C K E R M A N , M . , D . F R I M O U T , C . M U L L E R , D . N E V E J A N S , J . - C . F O N T A N E L L A , A . G I R A R D a n d N. L O U I S N A R D ( 1 9 7 3 ) . S t r a t o - s p h e r i c nitric oxide from i n f r a r e d s p e c t r a , N a t u r e , 245, 205-206.

A C K E R M A N , M . , J . - C . F O N T A N E L L A , D . F R I M O U T , A . G I R A R D , N . L O U I S N A R D a n d C . M U L L E R ( 1 9 7 5 ) . Simultaneous measurements of NO and NO£ in the s t r a t o s p h e r e , Planet. S p a c e S c i . , 23, 651-660.

B A K E R , K . D . , A . F. N A G V , R . O . O L S E N , E . S . O R A N , J. R A N D H A W A , D . F . S T R O B E L a n d T . T O H M A T S U (1977). Measurement of the nitric oxide altitude d i s t r i b u t i o n in the mid-latitude m e s o s p h e r e , J.

G e o p h y s . R e s . , 82, 3281-3286.

B A R T H , C . A . (1964). Rocket measurement of the nitric oxide d a y g l o w , J. G e o p h y s . R e s . , 69, 3301-3303.

L E M A I T R E , M . - P . , J. L A U R E N T , J. B E S S O N , A . G I R A R D , C . L I P P E N S , C . M U L L E R , J. V E R C H E V A L and M. A C K E R M A N ( 1 9 8 4 ) . Sample performance of the grille spectrometer, Science, 225, 171- 172.

M E I R A , L . G . , J r . (1971). Rocket measurements of the u p p e r atmo- s p h e r i c nitric oxide and their c o n s e q u e n c e s to the lower iono- s p h e r e , J. G e o p h y s . R e s . , 76, 202-212.

N I C O L E T , M. (1945). C o n t r i b u t i o n à l'étude de la s t r u c t u r e de l'iono- s p h è r e , I n s t . R o y . Météorol. B e l g . Mem., 19' 1-143.

R O T H M A N , L . S . , R . R . G A M A C H E , A . B A R B E , A . G O L D M A N , J . R . G I L L I S , L . R . B R O W N , R. A . T O T H , J . - M . F L A U D and C . C A M Y - P E Y R E T , A . F . G . L . atmospheric a b s o r p t i o n line parameters compilation : 1982 edition, - A p p l . O p t . 22, 2247 (1983).

R U S S E L , J. M. I l l , S . S O L O M O N , L . L . G O R D L E Y , E . E . R E M S B E R G a n d L . B . C A L L I S (1984). T h e variability of s t r a t o s p h e r i c a n d meso- s p h e r i c NO£ in the polar winter n i g h t o b s e r v e d b y L I M S , J. Geo- p h y s . R e s . , 89, 7267-7275.

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