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Variation of Jupiter's CH4 and NH3 bands with position on the planetary disk
ICARUS 21, 47--54 (1974)
Variation of Jupiter's CH4 and NH3 Bands with Position on the Planetary Disk REXFORD W. AVERy,1 J O S E P H J. MICHALSKY, JR., AND
R O B E R T A. ST O K E S 1
Battelle Observatory, Richland, Washington, and Department of Physics and Astronomy, University of Kentucky, Lexingtonl Kentucky R e c e i v e d M a y 8, 1973; r e v i s e d A u g u s t 6, 1973 W e r e p o r t h e r e t h e results o f r e c e n t s p e c t r o p h o t o m e t r i e scans o f t h e 6190 A a n d 7290A m e t h a n e b a n d s a n d t h e 6450A a m m o n i a b a n d on J u p i t e r as a f u n c t i o n o f p o s i t i o n on t h e p l a n e t a r y disk. The e q u i v a l e n t w i d t h s are f o u n d to decrease t o w a r d t h e e q u a t o r i a l l i m b a n d t o increase t o w a r d t h e poles relative t o t h e c e n t e r o f t h e disk.
I . INTRODUCTION
Recent theoretical work by a number of investigators (Hunt, 1973 ; Michalsky et al., 1973) has indicated t hat careful observations of the spatial variations in the strength of absorption features might be used to narrow the range of atmospheric models used for the study of the giant planets. I t has become clear t h a t even the gross observational features are inconsistent with the reflecting layer models which have traditionally been used for interpretation of spectra (MeElroy, 1969). The use of multilayer scattering models to represent the upper cloud decks has been shown to be more consistent with observations (Danielson and Tomasko, 1969); however, available observational data has not permitted a satisfactory characterization of the scattering layers. The observations reported here were made in an a t t e m p t to ascertain whether center-tolimb variations in widths of absorption features can be used to determine the gross vertical structure in a cloudy atmosphere. An effort was made to obtain high spatial t Visiting Astronomer, K i t t Peak National O b s e r v a t o r y , w h i c h is o p e r a t e d b y t h e Associat i o n o f U n i v e r s i t i e s for R e s e a r c h in A s t r o n o m y , Inc., u n d e r c o n t r a c t w i t h t h e N a t i o n a l Science Foundation. Copyright © 1974by AcademicPress, Inc. 47 All rights of reproductionin any form reserved. Printed in Great Britain
resolution data which exhibited changes in band strength as a function of the angle of incidence and reflection of the incident solar radiation. The results can thus be compared directly to theoretical band variations computed for various models. II.
OBSERVATIONS
The observational data were obtained with the K P N O 84" and the K P N O low resolution scanner on J u l y 14-17, 1972. The scanner was operated in the first order with an S-20 detector. Jupi t er was scanned in the sequential mode between 2&66506010 and AA7490-7010 with spectral and spatial resolutions of 8A (AA = 8• and 2A/Ax = 8A). The sky-compensating feature of the scanner was not used. The effective spatial resolution (instrumental plus estimated random and systematic guiding errors) of Jupiter's disk was approximately 4.5 arcsec. Guiding was accomplished by use of the wide field viewer which precedes the focal plane. Jupi t er itself was used as the guide object. The position of the entrance aperture on the disk was estimated visually. Each observation consisted of as many scans as necessary to accumulate between 20 000 and 30 000 counts in t h e brightest channel. The observational sequence
48
AVERY, MICHALSK¥, JR.~ AND STOKES
started at the center of the disk and proceeded toward the N, E, S, or W limb in steps of about .2 radii. The sequence was then restarted at the center and proceeded to the opposite limb. Observations were made along both the equator and the central meridian. The Moon was used as the comparison source in order to remove any terrestrial or solar contributions to the line spectra of Jupiter. Visual inspection of the raw data (counts vs wavelength) showed no large variations of the 7290A methane band. The weak ammonia and methane bands were obviously varying with position on the disk. The profiles of the 7290A band at the north and south poles and the weak bands at either limb showed large variations and greatly reduced equivalent widths. We attribute much of the variation to difficulties in guiding at the limb and to terrestially scattered light. We have chosen not to report these measurements because of their highly questionable accuracy. TABLE
The reduction of the data to normalized profiles and equivalent widths followed standard procedures. The normalized lunar scans were first divided into the Jovian scans. The corrected scans were then normalized, using handdrawn continuum levels. The estimated uncertainty in the continuum level is ~2%. The straight average of all profiles at each position were computed. These were integrated numberically to yield the equivalent widths (Table I and Figs. 1-4) as a function of position on the disk. The adopted profiles given in Tables I I - V and Fig. 5 represent smoothed average profiles and have the same equivalent widths as given in Table I. The uncertainties in the disk position (±0.1 planetary radius) are the combined rms estimates of the instrumental spatial resolution and guiding errors. The estimated errors in the equivalent widths of the 6190 A CH 4 and 6450 A N H 3 bands are largely due to uncertainties in the continuum levels and to blending corrections I
EQUIVALENT WIDTHS AND POSITIONS OF MEASURED PROFILES I~H 3 6 5 4 0 A profiles
C H , 6190J~ profiles Position
Eq. W.
# Obs.
Position
A 0.0E-W 0.2E-W 0.4E 0.6E-W 0.8E-W
2 2 1 2 2
0.0E-W 0.3E-W 0.4E 0.6E-W 0.8E-W
Eq. W.
72.8 71.3 71.6 71.6 66.7 66.9 65.0
± ~: ± ± ± ± i
3.3±0.6 3.7±0.6 2.0±0.7 1.9±0.6 1.6±0.6
2 2 1 2 2
C H 4 7 2 9 0 A profiles # Obs.
Position
A 0.0 E - W 0.2 E - W 0.4 E - W 0.5 E - W 0.6 E - W 0.8 E - W 0.95 E - W
# Obs.
A
17.6±1.2 17.5±1.2 17.0±1.0 14.9±1.2 15.7il.2 C H 4 7290/~ profiles
Position
Eq. W.
Eq. W.
# Obs.
A 2.3 2.2 2.4 1.8 2.4 3.1 4.0
11 4 2 2 3 4 4
0.0 0.2 0.4 0.5 0.8 0.8 0.8
N-S N-S N-S 1~ S N-S
72.8 ± 73.1 ~ -76.1 ± 75.7 ± 83.4 ± 79.6 ±
2.3 1.1 2.0 2.5 1.3 4.5
11 4 -4 2 2 4
JUPITER'S C H 4 AND ~ H ] BANDS
49
TABLE II Ctt4 7 2 9 0 A PROFILES, EAST--WEST )~ 7146 54 62 70 78 86 7194 7202 10 18 26 34 42 50 58 66 74 82 90 7298 7306 14 22 30 38 46 54 62 70 78 86 7394 7402 10 18 26 34 42 50 58 66 7474
0.0
0.2
0.4
0.5
0.6
0.8
.95
1.000 1.000 .985 .960 .925 .895 .855 .815 .771 .735 .690 .658 .625 .585 .534 .489 .454 .444 .462 .502 .540 .580 .617 .650 .685 .721 .757 .790 .818 .847 .871 .897 .916 .937 .954 .972 .985 .995 .999 1,000 1,000 1.000
1.000 .999 .995 .984 .952 .914 .875 .838 .785 .744 .700 .662 .628 .586 .543 .507 .474 .445 .437 .489 .529 .567 .604 .647 .697 .733 .770 .805 .833 .858 .882 .904 .924 .945 .963 .976 .986 .995 1.000 1.000 1.000 1.000
1.000 1.000 .995 .979 .950 .915 .881 .846 .804 .762 .727 .687 .649 .610 .572 .532 .498 .479 .485 .524 .562 .596 .630 .662 .699 .742 .777 .810 .834 .862 .885 .905 .921 .932 .945 .957 .969 .981 .990 .997 .999 1.000
1.000 .995 .982 .965 .938 .905 .868 .821 .875 .750 .713 .675 .630 .585 .540 .507 .475 .454 .466 .500 .536 .585 .620 .654 .687 .725 .759 .794 .825 .850 .875 .897 .915 .934 .947 .957 .969 .981 .991 .998 1.000 1.000
1,000 1,000 1,000 ,999 .983 .942 .902 .859 .818 .774 .733 .679 .628 .578 .526 .477 .452 .439 .454 .496 .539 .584 .628 .674 .715 .758 .797 .823 .849 .885 .899 .923 .943 .958 .973 .984 .995 1.000 1.000 1.000 l.OOO 1,000
1.000 1.000 1.000 .990 .963 .926 .888 .847 .807 .771 .736 .695 .656 .614 .563 .512 .471 .448 .424 .510 .545 .588 .634 .672 .712 .749 .785 .816 .844 .863 .887 .909 .929 .944 .958 .968 .978 .987 .995 1.000 1.000 1.000
1.000 1.000 .999 .992 .965 .935 .903 .870 .830 .792 .754 .713 .765 .642 .600 .549 .504 .470 .475 .520 .570 .610 .646 .680 .715 .744 .771 .797 .823 .845 .865 .886 .906 .925 .940 .954 .965 .975 .995 .992 1.000 1.000
i n t h e w i n g s . T h e 6450/t~ b a n d a p p e a r s t o be partially blended and has an ill-defined continuum level. The quoted errors for the 7290 A CH 4 band were calculated directly from each data set. There are two important sources of possible systematic errors in the 7290/~
measurements. First, the assumed continuum was found by drawing a straight line between the apparent terminations of the blue and red wings. This procedure could have had the effect of weakening the central portion of the profile in relation to the wings and would cause an overall
50
AVER)/, MICttALSKY, JR., AND STOKES T
T
T
"[
84 (S) 82 -
o~
80 (N-S)
78 -~ 76
L--
(N)
72
1
70 0.0
L
0.2
0.5
0.4
0.8
r/RjuPIIER
FIG. l. V a r i a t i o n o f t h e 7 2 9 0 ~ CH4 b a n d along t h e c e n t r a l m e r i d i a n .
decrease in the equivalent width. This possible systematic is estimated to be no greater than - 0 to ÷SA in equivalent width. Second, the terrestrial H~O band at 7190A is strongly blended with the blue wing of the 7290A band. Since the same lunar observations were used for all scans, any error in the lunar corrections will result in a systematic error. The largest possible systematic error in the equivalent width due to blending is estimated at ±5 A. The overall systematic error in the equivalent widths of the 7290A band is
estimated to be no greater than - 5 to +7 A. These possible systematic errors affect all profiles and equivalent widths in the same manner--i.e., scale factor errors may exist, but significant differential errors probably do not exist. III. RESULTS Table I and Figs. 1 and 2 show that the strength of the 7290 A CH 4 band increases with latitude along the central meridian (about 10%) and decreases with longitude I
I
,~ -
I
t
70
V-
54 52 60
I
I
I
I
0.0
0.2
0.4
0.5
] 0.8
r/RjuPIER
FIG. 2. E q u a t o r i a l v a r i a t i o n o f t h e 7290• CH4 b a n d .
1.0
JUPITER'S C H 4 AND N H s BANDS
18
51
I
I
I
[ 0.4
I 0.6
I 0.8
-
l? o~
14
[ 0.0
I 0.2
rlRjupITER
FIa. 3. Equatorial variation of the 6190A CH4 band. along t h e e q u a t o r (about 10%). T h e 6190 A C H 4 b a n d also decreases a b o u t 10% f r o m center v a l u e as t h e E - W limbs are a p p r o a c h e d . T h e 6450/~ N H s b a n d shows a m u c h larger decrease as t h e E - W " limbs arc a p p r o a c h e d . T h e reality of t h e decreasing e q u i v a l e n t widths w i t h increasing longitude c a n n o t be questioned. Because of t h e p r o b l e m s associated w i t h the m e a s u r e m e n t of the N H 3 6450 A b a n d , the e x a c t q u a n t i t a t i v e v a l u e m a y be subject to some doubt. H o w e v e r , the q u a l i t a t i v e results are valid.
T h e profiles of each b a n d b e h a v e in a similar m a n n e r as t h e e q u a t o r i a l limb is a p p r o a c h e d . T h e wings of the b a n d b e c o m e less intense a n d t h e central d e p t h of t h e b a n d decreases slightly; i.e., the b a n d s b e c o m e w e a k e r a n d narrower. IV. COMPARISON TO THE I~ESULTS OF TEIFEL J u p i t e r ' s 6190, 6450, a n d 7290A b a n d s h a v e also been studied b y Teifel (1969, 1970). The m e t h o d s of o b s e r v a t i o n a n d I
4.0
3.5
o~ 3.0
,--- 2,5
}
N ~.o 1.5
! +++
1.0
I
[
I
[
I
0
0.2
0.4
0.6
0.8
r/RjuPITE R
FIG. 4. Variation of the 6450A NH 3 band along the equator.
~2
AVERY, MICHALSKY~ JR., AND STOKES TABLE III CH4 7290A PnOFILES, NORT~I--SOUTH A
0.2
0.6
0.8 (N)
o.8 (s)
7146 54 62 70 78 86 7194 7202 16 18 26 34 42 50 58 66 74 82 90 7298 7306 14 22 30 38 46 54 7362 70 78 86 7394 7402 10 18 26 34 42 50 56 7466
1.000 1.000 .987 .965 .935 .901 .864 .825 .775 .737 .700 .665 .623 .580 .529 .484 .450 .439 .445 .481 .525 .575 .615 .653 .690 .726 .760 .793 .821 .848 .875 .902 .920 .936 .952 .966 .976 .986 .995 1.000 1.000
1.000 .997 .984 .967 .936 .900 .862 .818 .775 .730 .685 .645 .604 .560 .505 .442 .406 .394 .415 .455 .500 .551 .592 .633 .672 .713 .742 .785 .822 .855 .891 .901 .919 .936 .950 .966 .979 .989 .997 1.000 1.000
1.000 .997 .977 .950 .920 .888 .852 .808 .767 .733 .693 .653 .603 .547 .489 .439 .392 .377 .408 .462 .50s .559 .600 .641 .676 .725 .768 .808 .840 .866 .892 .916 .939 .961 .980 .993 1.000 1.000 1.000 1.000 1.000
1.000 .997 .968 .935 .898 .860 .825 .779 .732 .692 .657 .627 .575 .525 .468 .421 .389 .371 .397 .437 .480 .527 .565 .609 .658 .701 .743 .772 .800 .825 .850 .873 .896 .916 .936 .955 .969 . 983 .992 .998 1.000
reduction for this work and that of Teifel are similar, except for spatial resolution. O u r s p a t i a l r e s o l u t i o n is a b o u t 4", w h e r e a s T e i f e l ' s s p e c t r o g r a p h i c r e s o l u t i o n is a b o u t 16". T e i f e l ' s 11969) r e s u l t s f o r t h e 6 1 9 0 , 6 4 5 0 , and 7290A bands at the center of the disk
are slightly larger than ours. We do not consider the difference as being significant. Teifel (1970) concentrated on the spatial variation of the 7290 A CH 4 band. While the trends (equivalent width increases toward the poles and decreases toward the limb relative to the center) and absolute
53
J U P I T E R ' S C H 4 AND N H 3 BANDS TABLE IV CH4 6 1 9 0 A P~OFILES
6042 50 58 66 74 82 90 6098 6106 14 22 30 38 46 54 62 70 78 86 6194 6202 10 18 26 34 42 50 58 66 74 82 90 6298 6306 6314 6322
0.0
0.2
0.4
0.6
0.8
1.000 1.000 1.000 1.000 1.000 1.000 .998 .994 .984 .970 .956 .942 .927 .913 .896 .878 .856 .845 .821 .808 .812 .829 .855 .882 .902 .923 .941 .955 .964 .974 .983 .991 .997 1.000 1.000 1.000
1.000 .999 .995 .993 .993 .987 .983 .979 .972 .965 .951 .936 .918 .906 .894 .880 .866 .849 .834 .824 .822 .841 .863 .882 .901 .925 .943 .958 .970 .979 .988 .995 .998 1.000 1.000 1.000
1.000 1.000 .999 .995 .990 .986 .981 .975 .970 .963 .956 .946 .933 .920 .907 .892 .877 .856 .835 .814 .828 .845 .866 .888 .917 .933 .946 .958 .968 .975 .981 .986 .991 .996 .999 1.000
1.000 1.000 1.000 1.000 1.000 .999 .994 .989 .984 .967 .955 .941 .926 .912 .900 .886 .869 .853 .844 .837 .852 .861 .876 .895 .915 .946 .957 .979 .989 .997 1.000 1.000 1.000 1.000 1.000 1.000
1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 .995 .986 .972 .956 .942 .927 .913 .896 .878 .859 .839 .810 .826 .849 .869 .884 .902 .920 .936 .953 .966 .980 .987 .993 .999 1.000 1.000 1.000
changes in equivalent width are very similar both in our work and Teifel's (1970), Teifel's values are 40% larger than ours and 30% larger than his 1969 value at the center of the disk. The cause of these very large differences is not known. A comparison of band profiles would be of great value in attempting to find the source of conflicting results. Unfortunately, Teifel (1973) has informed us t h a t neither individual nor mean profiles are available at this time.
V . CONCLUSIONS
Relative to the equivalent widths at the center of the disk, the 6190/~ and 7290A bands of methane and the 6450 A band of ammonia decrease in strength as the equatorial limbs are approached. The decrease in the ammonia band m ay approach 40%. The 7290A CI~ 4 band increases in strength toward the poles along the central meridian. There may be an a s y m m e t r y at the poles.
54
AVERY, MICHALSKY, JR., AI~D STOKES TABLE V N H a 6 4 5 0 ~ PROFILES A
0.0
0.2
0.4
0.6
0.8
6386 6394 6402 10 18 26 34 42 50 58 66 74 82 6490
1.000 .998 .995 .989 .983 .975 .959 .922 .898 .926 .959 .983 .996 1.000
1.000 .996 .990 .983 .975 .964 .947 .919 .903 .922 .962 .982 .995 1.000
1.000 1.000 1.000 1.000 .997 .988 .969 .949 .939 .945 .963 .994 1.000 1.000
1.000 1.000 1.000 .999 .996 .987 .967 .948 .931 .953 .98I .996 .999 1.0O0
1.000 1.000 1.000 1.000 1.000 .998 .986 .951 .935 .953 .983 .997 1.000 1.000
1.0
0.9 0.8 >- 0.3 -~ 0.6
0.5
0.4 0.3 70~
I
r
I
[
I
r
I
1146
1194
1242
7290
73~
7386
?4)4
7458
FIG. 5. 7 2 9 0 A C H , b a n d profile a t t h e c e n t e r of J u p i t e r ' s disk. On the basis of this work and that of Teifel, the equivalent widths at the center of Jupiter's disk of the 6190, 6450, and 7290A bands can be taken as 19±2, 4 ± 1, a n d 77 ± 3 A , r e s p e c t i v e l y . REFERENCES DANIELSON, R. E., AND TOMASKO, M. G. (1969). A t w o l a y e r m o d e l of t h e J o v i a n clouds. J . Atmos. Sci. 26, 889-897. HUNT, G. E. (1973). F o r m a t i o n of s p e c t r a l lines in p l a n e t a r y a t m o s p h e r e . IV. T h e o r e t i c a l evid e n c e for s t r u c t u r e of t h e J o v i a n clouds f r o m spectroscopic o b s e r v a t i o n s of m e t h a n e a n d h y d r o g e n q u a d r u p o l e lines. Icarus 18,637-648.
McELRoY, M. B. (1969). T h e a t m o s p h e r i c c o m p o s i t i o n of t h e J o v i a n p l a n e t s . J . Atmos. Sci. 26, 798-812. ~V[IcHALSKY, J . J., STOKES, l~. A., AVER~, R . W., AND DEMn-RCUS, W. C. (1973). M o l e c u l a r b a n d v a r i a t i o n s as a p r o b e of t h e v e r t i c a l s t r u c t u r e of a J o v i a n a t m o s p h e r e . ]carus, in press. TEIFEL, V. (~x. (1969). Molecular a b s o r p t i o n a n d t h e possible s t r u c t u r e of t h e cloud layers of J u p i t e r a n d S a t u r n . J. Atmos. Sci. 26, 854-859. TEIFET,, V. G. (1970). Optical c h a r a c t e r i s t i c s a n d c o m p o s i t i o n of J u p i t e r a t m o s p h e r e IV. R e s u l t s of p h o t o e l e c t r i c s p e c t r o p h o t o m e t r y in t h e 6 3 0 0 - 8 1 0 0 A range. Astronomicheskii Vestnilc 5, 222-231. TEIFEL, V. Cx. (1973). P r i v a t e c o m m u n i c a t i o n .
Variation of Jupiter's CH4 and NH3 Bands with Position on the Planetary Disk REXFORD W. AVERy,1 J O S E P H J. MICHALSKY, JR., AND
R O B E R T A. ST O K E S 1
Battelle Observatory, Richland, Washington, and Department of Physics and Astronomy, University of Kentucky, Lexingtonl Kentucky R e c e i v e d M a y 8, 1973; r e v i s e d A u g u s t 6, 1973 W e r e p o r t h e r e t h e results o f r e c e n t s p e c t r o p h o t o m e t r i e scans o f t h e 6190 A a n d 7290A m e t h a n e b a n d s a n d t h e 6450A a m m o n i a b a n d on J u p i t e r as a f u n c t i o n o f p o s i t i o n on t h e p l a n e t a r y disk. The e q u i v a l e n t w i d t h s are f o u n d to decrease t o w a r d t h e e q u a t o r i a l l i m b a n d t o increase t o w a r d t h e poles relative t o t h e c e n t e r o f t h e disk.
I . INTRODUCTION
Recent theoretical work by a number of investigators (Hunt, 1973 ; Michalsky et al., 1973) has indicated t hat careful observations of the spatial variations in the strength of absorption features might be used to narrow the range of atmospheric models used for the study of the giant planets. I t has become clear t h a t even the gross observational features are inconsistent with the reflecting layer models which have traditionally been used for interpretation of spectra (MeElroy, 1969). The use of multilayer scattering models to represent the upper cloud decks has been shown to be more consistent with observations (Danielson and Tomasko, 1969); however, available observational data has not permitted a satisfactory characterization of the scattering layers. The observations reported here were made in an a t t e m p t to ascertain whether center-tolimb variations in widths of absorption features can be used to determine the gross vertical structure in a cloudy atmosphere. An effort was made to obtain high spatial t Visiting Astronomer, K i t t Peak National O b s e r v a t o r y , w h i c h is o p e r a t e d b y t h e Associat i o n o f U n i v e r s i t i e s for R e s e a r c h in A s t r o n o m y , Inc., u n d e r c o n t r a c t w i t h t h e N a t i o n a l Science Foundation. Copyright © 1974by AcademicPress, Inc. 47 All rights of reproductionin any form reserved. Printed in Great Britain
resolution data which exhibited changes in band strength as a function of the angle of incidence and reflection of the incident solar radiation. The results can thus be compared directly to theoretical band variations computed for various models. II.
OBSERVATIONS
The observational data were obtained with the K P N O 84" and the K P N O low resolution scanner on J u l y 14-17, 1972. The scanner was operated in the first order with an S-20 detector. Jupi t er was scanned in the sequential mode between 2&66506010 and AA7490-7010 with spectral and spatial resolutions of 8A (AA = 8• and 2A/Ax = 8A). The sky-compensating feature of the scanner was not used. The effective spatial resolution (instrumental plus estimated random and systematic guiding errors) of Jupiter's disk was approximately 4.5 arcsec. Guiding was accomplished by use of the wide field viewer which precedes the focal plane. Jupi t er itself was used as the guide object. The position of the entrance aperture on the disk was estimated visually. Each observation consisted of as many scans as necessary to accumulate between 20 000 and 30 000 counts in t h e brightest channel. The observational sequence
48
AVERY, MICHALSK¥, JR.~ AND STOKES
started at the center of the disk and proceeded toward the N, E, S, or W limb in steps of about .2 radii. The sequence was then restarted at the center and proceeded to the opposite limb. Observations were made along both the equator and the central meridian. The Moon was used as the comparison source in order to remove any terrestrial or solar contributions to the line spectra of Jupiter. Visual inspection of the raw data (counts vs wavelength) showed no large variations of the 7290A methane band. The weak ammonia and methane bands were obviously varying with position on the disk. The profiles of the 7290A band at the north and south poles and the weak bands at either limb showed large variations and greatly reduced equivalent widths. We attribute much of the variation to difficulties in guiding at the limb and to terrestially scattered light. We have chosen not to report these measurements because of their highly questionable accuracy. TABLE
The reduction of the data to normalized profiles and equivalent widths followed standard procedures. The normalized lunar scans were first divided into the Jovian scans. The corrected scans were then normalized, using handdrawn continuum levels. The estimated uncertainty in the continuum level is ~2%. The straight average of all profiles at each position were computed. These were integrated numberically to yield the equivalent widths (Table I and Figs. 1-4) as a function of position on the disk. The adopted profiles given in Tables I I - V and Fig. 5 represent smoothed average profiles and have the same equivalent widths as given in Table I. The uncertainties in the disk position (±0.1 planetary radius) are the combined rms estimates of the instrumental spatial resolution and guiding errors. The estimated errors in the equivalent widths of the 6190 A CH 4 and 6450 A N H 3 bands are largely due to uncertainties in the continuum levels and to blending corrections I
EQUIVALENT WIDTHS AND POSITIONS OF MEASURED PROFILES I~H 3 6 5 4 0 A profiles
C H , 6190J~ profiles Position
Eq. W.
# Obs.
Position
A 0.0E-W 0.2E-W 0.4E 0.6E-W 0.8E-W
2 2 1 2 2
0.0E-W 0.3E-W 0.4E 0.6E-W 0.8E-W
Eq. W.
72.8 71.3 71.6 71.6 66.7 66.9 65.0
± ~: ± ± ± ± i
3.3±0.6 3.7±0.6 2.0±0.7 1.9±0.6 1.6±0.6
2 2 1 2 2
C H 4 7 2 9 0 A profiles # Obs.
Position
A 0.0 E - W 0.2 E - W 0.4 E - W 0.5 E - W 0.6 E - W 0.8 E - W 0.95 E - W
# Obs.
A
17.6±1.2 17.5±1.2 17.0±1.0 14.9±1.2 15.7il.2 C H 4 7290/~ profiles
Position
Eq. W.
Eq. W.
# Obs.
A 2.3 2.2 2.4 1.8 2.4 3.1 4.0
11 4 2 2 3 4 4
0.0 0.2 0.4 0.5 0.8 0.8 0.8
N-S N-S N-S 1~ S N-S
72.8 ± 73.1 ~ -76.1 ± 75.7 ± 83.4 ± 79.6 ±
2.3 1.1 2.0 2.5 1.3 4.5
11 4 -4 2 2 4
JUPITER'S C H 4 AND ~ H ] BANDS
49
TABLE II Ctt4 7 2 9 0 A PROFILES, EAST--WEST )~ 7146 54 62 70 78 86 7194 7202 10 18 26 34 42 50 58 66 74 82 90 7298 7306 14 22 30 38 46 54 62 70 78 86 7394 7402 10 18 26 34 42 50 58 66 7474
0.0
0.2
0.4
0.5
0.6
0.8
.95
1.000 1.000 .985 .960 .925 .895 .855 .815 .771 .735 .690 .658 .625 .585 .534 .489 .454 .444 .462 .502 .540 .580 .617 .650 .685 .721 .757 .790 .818 .847 .871 .897 .916 .937 .954 .972 .985 .995 .999 1,000 1,000 1.000
1.000 .999 .995 .984 .952 .914 .875 .838 .785 .744 .700 .662 .628 .586 .543 .507 .474 .445 .437 .489 .529 .567 .604 .647 .697 .733 .770 .805 .833 .858 .882 .904 .924 .945 .963 .976 .986 .995 1.000 1.000 1.000 1.000
1.000 1.000 .995 .979 .950 .915 .881 .846 .804 .762 .727 .687 .649 .610 .572 .532 .498 .479 .485 .524 .562 .596 .630 .662 .699 .742 .777 .810 .834 .862 .885 .905 .921 .932 .945 .957 .969 .981 .990 .997 .999 1.000
1.000 .995 .982 .965 .938 .905 .868 .821 .875 .750 .713 .675 .630 .585 .540 .507 .475 .454 .466 .500 .536 .585 .620 .654 .687 .725 .759 .794 .825 .850 .875 .897 .915 .934 .947 .957 .969 .981 .991 .998 1.000 1.000
1,000 1,000 1,000 ,999 .983 .942 .902 .859 .818 .774 .733 .679 .628 .578 .526 .477 .452 .439 .454 .496 .539 .584 .628 .674 .715 .758 .797 .823 .849 .885 .899 .923 .943 .958 .973 .984 .995 1.000 1.000 1.000 l.OOO 1,000
1.000 1.000 1.000 .990 .963 .926 .888 .847 .807 .771 .736 .695 .656 .614 .563 .512 .471 .448 .424 .510 .545 .588 .634 .672 .712 .749 .785 .816 .844 .863 .887 .909 .929 .944 .958 .968 .978 .987 .995 1.000 1.000 1.000
1.000 1.000 .999 .992 .965 .935 .903 .870 .830 .792 .754 .713 .765 .642 .600 .549 .504 .470 .475 .520 .570 .610 .646 .680 .715 .744 .771 .797 .823 .845 .865 .886 .906 .925 .940 .954 .965 .975 .995 .992 1.000 1.000
i n t h e w i n g s . T h e 6450/t~ b a n d a p p e a r s t o be partially blended and has an ill-defined continuum level. The quoted errors for the 7290 A CH 4 band were calculated directly from each data set. There are two important sources of possible systematic errors in the 7290/~
measurements. First, the assumed continuum was found by drawing a straight line between the apparent terminations of the blue and red wings. This procedure could have had the effect of weakening the central portion of the profile in relation to the wings and would cause an overall
50
AVER)/, MICttALSKY, JR., AND STOKES T
T
T
"[
84 (S) 82 -
o~
80 (N-S)
78 -~ 76
L--
(N)
72
1
70 0.0
L
0.2
0.5
0.4
0.8
r/RjuPIIER
FIG. l. V a r i a t i o n o f t h e 7 2 9 0 ~ CH4 b a n d along t h e c e n t r a l m e r i d i a n .
decrease in the equivalent width. This possible systematic is estimated to be no greater than - 0 to ÷SA in equivalent width. Second, the terrestrial H~O band at 7190A is strongly blended with the blue wing of the 7290A band. Since the same lunar observations were used for all scans, any error in the lunar corrections will result in a systematic error. The largest possible systematic error in the equivalent width due to blending is estimated at ±5 A. The overall systematic error in the equivalent widths of the 7290A band is
estimated to be no greater than - 5 to +7 A. These possible systematic errors affect all profiles and equivalent widths in the same manner--i.e., scale factor errors may exist, but significant differential errors probably do not exist. III. RESULTS Table I and Figs. 1 and 2 show that the strength of the 7290 A CH 4 band increases with latitude along the central meridian (about 10%) and decreases with longitude I
I
,~ -
I
t
70
V-
54 52 60
I
I
I
I
0.0
0.2
0.4
0.5
] 0.8
r/RjuPIER
FIG. 2. E q u a t o r i a l v a r i a t i o n o f t h e 7290• CH4 b a n d .
1.0
JUPITER'S C H 4 AND N H s BANDS
18
51
I
I
I
[ 0.4
I 0.6
I 0.8
-
l? o~
14
[ 0.0
I 0.2
rlRjupITER
FIa. 3. Equatorial variation of the 6190A CH4 band. along t h e e q u a t o r (about 10%). T h e 6190 A C H 4 b a n d also decreases a b o u t 10% f r o m center v a l u e as t h e E - W limbs are a p p r o a c h e d . T h e 6450/~ N H s b a n d shows a m u c h larger decrease as t h e E - W " limbs arc a p p r o a c h e d . T h e reality of t h e decreasing e q u i v a l e n t widths w i t h increasing longitude c a n n o t be questioned. Because of t h e p r o b l e m s associated w i t h the m e a s u r e m e n t of the N H 3 6450 A b a n d , the e x a c t q u a n t i t a t i v e v a l u e m a y be subject to some doubt. H o w e v e r , the q u a l i t a t i v e results are valid.
T h e profiles of each b a n d b e h a v e in a similar m a n n e r as t h e e q u a t o r i a l limb is a p p r o a c h e d . T h e wings of the b a n d b e c o m e less intense a n d t h e central d e p t h of t h e b a n d decreases slightly; i.e., the b a n d s b e c o m e w e a k e r a n d narrower. IV. COMPARISON TO THE I~ESULTS OF TEIFEL J u p i t e r ' s 6190, 6450, a n d 7290A b a n d s h a v e also been studied b y Teifel (1969, 1970). The m e t h o d s of o b s e r v a t i o n a n d I
4.0
3.5
o~ 3.0
,--- 2,5
}
N ~.o 1.5
! +++
1.0
I
[
I
[
I
0
0.2
0.4
0.6
0.8
r/RjuPITE R
FIG. 4. Variation of the 6450A NH 3 band along the equator.
~2
AVERY, MICHALSKY~ JR., AND STOKES TABLE III CH4 7290A PnOFILES, NORT~I--SOUTH A
0.2
0.6
0.8 (N)
o.8 (s)
7146 54 62 70 78 86 7194 7202 16 18 26 34 42 50 58 66 74 82 90 7298 7306 14 22 30 38 46 54 7362 70 78 86 7394 7402 10 18 26 34 42 50 56 7466
1.000 1.000 .987 .965 .935 .901 .864 .825 .775 .737 .700 .665 .623 .580 .529 .484 .450 .439 .445 .481 .525 .575 .615 .653 .690 .726 .760 .793 .821 .848 .875 .902 .920 .936 .952 .966 .976 .986 .995 1.000 1.000
1.000 .997 .984 .967 .936 .900 .862 .818 .775 .730 .685 .645 .604 .560 .505 .442 .406 .394 .415 .455 .500 .551 .592 .633 .672 .713 .742 .785 .822 .855 .891 .901 .919 .936 .950 .966 .979 .989 .997 1.000 1.000
1.000 .997 .977 .950 .920 .888 .852 .808 .767 .733 .693 .653 .603 .547 .489 .439 .392 .377 .408 .462 .50s .559 .600 .641 .676 .725 .768 .808 .840 .866 .892 .916 .939 .961 .980 .993 1.000 1.000 1.000 1.000 1.000
1.000 .997 .968 .935 .898 .860 .825 .779 .732 .692 .657 .627 .575 .525 .468 .421 .389 .371 .397 .437 .480 .527 .565 .609 .658 .701 .743 .772 .800 .825 .850 .873 .896 .916 .936 .955 .969 . 983 .992 .998 1.000
reduction for this work and that of Teifel are similar, except for spatial resolution. O u r s p a t i a l r e s o l u t i o n is a b o u t 4", w h e r e a s T e i f e l ' s s p e c t r o g r a p h i c r e s o l u t i o n is a b o u t 16". T e i f e l ' s 11969) r e s u l t s f o r t h e 6 1 9 0 , 6 4 5 0 , and 7290A bands at the center of the disk
are slightly larger than ours. We do not consider the difference as being significant. Teifel (1970) concentrated on the spatial variation of the 7290 A CH 4 band. While the trends (equivalent width increases toward the poles and decreases toward the limb relative to the center) and absolute
53
J U P I T E R ' S C H 4 AND N H 3 BANDS TABLE IV CH4 6 1 9 0 A P~OFILES
6042 50 58 66 74 82 90 6098 6106 14 22 30 38 46 54 62 70 78 86 6194 6202 10 18 26 34 42 50 58 66 74 82 90 6298 6306 6314 6322
0.0
0.2
0.4
0.6
0.8
1.000 1.000 1.000 1.000 1.000 1.000 .998 .994 .984 .970 .956 .942 .927 .913 .896 .878 .856 .845 .821 .808 .812 .829 .855 .882 .902 .923 .941 .955 .964 .974 .983 .991 .997 1.000 1.000 1.000
1.000 .999 .995 .993 .993 .987 .983 .979 .972 .965 .951 .936 .918 .906 .894 .880 .866 .849 .834 .824 .822 .841 .863 .882 .901 .925 .943 .958 .970 .979 .988 .995 .998 1.000 1.000 1.000
1.000 1.000 .999 .995 .990 .986 .981 .975 .970 .963 .956 .946 .933 .920 .907 .892 .877 .856 .835 .814 .828 .845 .866 .888 .917 .933 .946 .958 .968 .975 .981 .986 .991 .996 .999 1.000
1.000 1.000 1.000 1.000 1.000 .999 .994 .989 .984 .967 .955 .941 .926 .912 .900 .886 .869 .853 .844 .837 .852 .861 .876 .895 .915 .946 .957 .979 .989 .997 1.000 1.000 1.000 1.000 1.000 1.000
1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 .995 .986 .972 .956 .942 .927 .913 .896 .878 .859 .839 .810 .826 .849 .869 .884 .902 .920 .936 .953 .966 .980 .987 .993 .999 1.000 1.000 1.000
changes in equivalent width are very similar both in our work and Teifel's (1970), Teifel's values are 40% larger than ours and 30% larger than his 1969 value at the center of the disk. The cause of these very large differences is not known. A comparison of band profiles would be of great value in attempting to find the source of conflicting results. Unfortunately, Teifel (1973) has informed us t h a t neither individual nor mean profiles are available at this time.
V . CONCLUSIONS
Relative to the equivalent widths at the center of the disk, the 6190/~ and 7290A bands of methane and the 6450 A band of ammonia decrease in strength as the equatorial limbs are approached. The decrease in the ammonia band m ay approach 40%. The 7290A CI~ 4 band increases in strength toward the poles along the central meridian. There may be an a s y m m e t r y at the poles.
54
AVERY, MICHALSKY, JR., AI~D STOKES TABLE V N H a 6 4 5 0 ~ PROFILES A
0.0
0.2
0.4
0.6
0.8
6386 6394 6402 10 18 26 34 42 50 58 66 74 82 6490
1.000 .998 .995 .989 .983 .975 .959 .922 .898 .926 .959 .983 .996 1.000
1.000 .996 .990 .983 .975 .964 .947 .919 .903 .922 .962 .982 .995 1.000
1.000 1.000 1.000 1.000 .997 .988 .969 .949 .939 .945 .963 .994 1.000 1.000
1.000 1.000 1.000 .999 .996 .987 .967 .948 .931 .953 .98I .996 .999 1.0O0
1.000 1.000 1.000 1.000 1.000 .998 .986 .951 .935 .953 .983 .997 1.000 1.000
1.0
0.9 0.8 >- 0.3 -~ 0.6
0.5
0.4 0.3 70~
I
r
I
[
I
r
I
1146
1194
1242
7290
73~
7386
?4)4
7458
FIG. 5. 7 2 9 0 A C H , b a n d profile a t t h e c e n t e r of J u p i t e r ' s disk. On the basis of this work and that of Teifel, the equivalent widths at the center of Jupiter's disk of the 6190, 6450, and 7290A bands can be taken as 19±2, 4 ± 1, a n d 77 ± 3 A , r e s p e c t i v e l y . REFERENCES DANIELSON, R. E., AND TOMASKO, M. G. (1969). A t w o l a y e r m o d e l of t h e J o v i a n clouds. J . Atmos. Sci. 26, 889-897. HUNT, G. E. (1973). F o r m a t i o n of s p e c t r a l lines in p l a n e t a r y a t m o s p h e r e . IV. T h e o r e t i c a l evid e n c e for s t r u c t u r e of t h e J o v i a n clouds f r o m spectroscopic o b s e r v a t i o n s of m e t h a n e a n d h y d r o g e n q u a d r u p o l e lines. Icarus 18,637-648.
McELRoY, M. B. (1969). T h e a t m o s p h e r i c c o m p o s i t i o n of t h e J o v i a n p l a n e t s . J . Atmos. Sci. 26, 798-812. ~V[IcHALSKY, J . J., STOKES, l~. A., AVER~, R . W., AND DEMn-RCUS, W. C. (1973). M o l e c u l a r b a n d v a r i a t i o n s as a p r o b e of t h e v e r t i c a l s t r u c t u r e of a J o v i a n a t m o s p h e r e . ]carus, in press. TEIFEL, V. (~x. (1969). Molecular a b s o r p t i o n a n d t h e possible s t r u c t u r e of t h e cloud layers of J u p i t e r a n d S a t u r n . J. Atmos. Sci. 26, 854-859. TEIFET,, V. G. (1970). Optical c h a r a c t e r i s t i c s a n d c o m p o s i t i o n of J u p i t e r a t m o s p h e r e IV. R e s u l t s of p h o t o e l e c t r i c s p e c t r o p h o t o m e t r y in t h e 6 3 0 0 - 8 1 0 0 A range. Astronomicheskii Vestnilc 5, 222-231. TEIFEL, V. Cx. (1973). P r i v a t e c o m m u n i c a t i o n .