Farmer, C. B.

English

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Workshop on Early Detection of Stratospheric Changes.
March 5 - 7 , 198,6
SUMMARY OF THE RESULTS FROM ATMOS
C.B. Farmer
The ATMOS experiment was flown for the first time in April, 1985, as part
of the Spacelab 3 payload. The instrument is a Michelson interferometer
operating in the absorption (solar occultation) mode, covering the 2 to 16
microns wavelength range (600 to 4500 cm~l) at a resolution of 0.01 cm~l.
During the Spacelab 3 mission ATMOS recorded 12 sunset and 4 sunrise occul-
tations, on April 30th, and May 1st and 2nd. The sunsets occurred at
latitudes between 25 and 33° N and the sunrises between 47 and 49° S.
The reduction and analysis of the data has been carried out with the ATMOS
computer system, a dedicated facility at JPL with remote terminals at
several coinvestigator sites in the US and in Europe. The analysis is
currently proceeding towards the final determination of vertical profiles of:
1. Density, temperature and pressure;
2. Concentration of:
(i) minor gases
(ii) nitrogen trace species
(iii) halogen source gases
(iv) halogen products
(v) other trace gases;
3. Winds in the mesosphere and lower thermosphere;
4. Isotopic abundances.
In addition to these, useful upper limits (i.e. at or below the concentration
levels predicted by current photochemical models) are being determined for
other key species such as CIO, HOC1, H02, and 1^ 02.
An atlas of high signal-to-noise coadded spectra of the sun and of the upper
atmosphere, at tangent altitude intervals of approximately two scale heights,
is being prepared for publication later this year.
The Table summarises the altitude ranges over which the profiles of concen-
tration can be retrieved for each of the molecular constituents identified
in the ATMOS spectra thus far. In general, the precision of the retrieved
values of mixing ratio is about 10%, and can be better than 5% for con-
stituents which show a large number of spectral features (for example, 03,
C02, N20, HC1, HN03 etc.). The systematic uncertainties (excluding molecular
spectral parameters) are estimated to be between 10 and 20%, depending on
the spectral region involved. It is expected that these uncertainties will
be reduced considerably as the refinement of the analyses proceeds. Never-
theless, the precision achieved at the present time is sufficient to reveal
longitudinal variability (e.g. 1^ 0, 03), hemispheric (or diurnal) differences,
and vertical structure.
https://ntrs.nasa.gov/search.jsp?R=19910073978 2020-03-17T14:52:21+00:00Z
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The analysis of the first data set has necessitated a careful verification
and redefinition of the microwindows assigned to the species retrievals.
In turn the ATMOS spectra are proving to be of great value in clarifying
deficiencies in the basic molecular spectral parameters.
TABLE 1 MOLECULAR SPECIES IDENTIFIED IN THE ATMQS SPECTRA
Constituent
N2
C02
CO
H20
03
N20
CH4
NO
N02
,N205
HN03
HN04
CF4
Altitude Range (km)
Fll, 12,
CH3C1
22
HC1
HF
COF2
C10N0
OCS
HCN
C2H2
< 18
5
5
5
< 10
5
5
< 18
< 18
20
18
18
5
5
5
18
12
< 15
18
18
< 18
< 18
5
5
- 35
- 140
- 120
- 85
- 90
- 65
- 80
- 140
- 50
- 38
- 50
- 40
- .40
- 20
- ~ 35
- 35
- 60
- 55
- 40
- 35
- 20
- 30
- 14
- 10
Comments/Isotopes
Pressure at the tangent altitude
T,P,p; C12, C13, 016, 017, 018
C12, C13, 016, 017, 018
HDO between 5 and 35 km
03(16,16,18) < 20 to 42 km
C12, C13
Max. 1.6 x 10~9 at 32 km (sunrise)
Max. 3 x 1C)""10 at 28 km (sunset)
Several bands observed
Several Q branches
3 x 10~9 above 45 km
6 x 10~10 above 45 km
2 bands; max. ~ 1.3 x 10~10 near 32 kn
5 bands; max. ~ 1.5 x 10~* near 30 km
2 bands observed
February 1986


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