Global changes in the 0-70 km thermal structure of the Mars atmosphere derived from 1975 to 1989 microwave CO spectra

Conference · Thu Aug 30 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

OSTI ID:5384775

Clancy, R T ^[1]; Muhleman, D O; Berge, G L ^[2]

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1. Univ. of Colorado, Boulder (USA)
2. California Institute of Technology, Pasadena (USA)

Microwave spectra of Mars atmospheric CO were obtained in May (L{sub s}=197{degree}) and November (L{sub s}=305{degree}) of 1988 and January (L{sub s}=341{degree}) of 1989. The November observations, which include both {sup 12}CO and {sup 13}CO spectra, are analyzed to obtain the CO mixing ratio and temperature profile of the atmosphere of Mars for the 0-70 km altitude region. The resulting volume mixing ratio for CO (6{plus minus}1.5{times}10{sup {minus}4}) compares well with the 1967 infrared reflectance determination (8{plus minus}2{times}10{sup {minus}4}) by Kaplan et al. (1969). Based upon these observations and other ground-based observations of O{sub 2}, the authors suggest that large variations (>50%) in the global abundances of CO and O{sub 2} are not characteristic of the present Mars atmosphere. Assuming a constant CO mixing ratio, they derive atmospheric temperature profiles from the May 1988 and January 1989 {sup 12}CO spectra which are quite similar to the temperature profile found for the November 1988 period. The same analysis for {sup 12}CO spectra observed in November 1975, March-April 1980, and January 1982 yields Mars atmospheric temperature profiles which are distinctly different from the Viking northern summer profiles. The March-April 1980 and January 1982 profiles, in particular, are 20-40 K cooler than the Viking profile for altitudes above 10 km. They conjecture that, during such cold northern spring-summer seasons; condensation of H{sub 2}O{sub 2} above 20-30 km altitude may affect the altitude distribution of O{sub 3}; the base altitude of H{sub 2}O clouds may decrease to as low as 5-10 km; and CO{sub 2} condensation at low latitudes may occur locally in the 30-40 km altitude region. Finally, they propose 25 K solar longitudinal (L{sub s}) variations in low-to-mid-latitude temperatures for both dusty and clear periods of the Mars atmosphere.

• OSTI ID: 5384775
• Report Number(s): CONF-9001119--
• Conference Information: Journal Name: Journal of Geophysical Research; (United States) Journal Volume: 95:B9
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ATMOSPHERES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
ELEMENT ABUNDANCE
ELEMENTS
GLOBAL ASPECTS
MARS PLANET
MICROWAVE SPECTRA
MIXING
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PLANETARY ATMOSPHERES
PLANETS
SPECTRA
TEMPERATURE GRADIENTS
VARIATIONS