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Science 17 December 1976:
Vol. 194. no. 4271, pp. 1300 - 1303
DOI: 10.1126/science.194.4271.1300
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Articles

Structure of Mars' Atmosphere up to 100 Kilometers from the Entry Measurements of Viking 2

ALVIN SEIFF 1 and DONN B. KIRK 1

1 Space Science Division, NASA Ames Research Center, Moffett Field, California 94035

The Viking 2 entry science data on the structure of Mars' atmosphere up to 100 kilometers define a morning atmosphere with an isothermal region near the surface; a surface pressure 10 percent greater than that recorded simultaneously at the Viking 1 site, which implies a landing site elevation lower by 2.7 kilometers than the reference ellipsoid; and a thermal structure to 100 kilometers at least qualitatively consistent with pre-Viking modeling of thermal tides. The temperature profile exhibits waves whose amplitude grows with altitude, to sim25°K at 90 kilometers. These waves are believed to be a consequence of layered vertical oscillations and associated heating and cooling by compression and expansion, excited by the daily thermal cycling of the planet surface. As is necessary for gravity wave propagation, the atmosphere is stable against convection, except possibly in some very local regions. Temperature is everywhere appreciably above the carbon dioxide condensation boundary at both landing sites, precluding the occurrence of carbon dioxide hazes in northern summer at latitudes to at least 50°N. Thus, ground level mists seen in these latitudes would appear to be condensed water vapor.

Submitted on October 18, 1976


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Scientific Results of the Viking Missions.
G. A. Soffen and G. A. SOFFEN (1976)
Science 194, 1274-1276
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Composition and Structure of the Martian Upper Atmosphere: Analysis of Results from Viking.
M. B. McElroy, M. B. MCELROY, T. Y. KONG, Y. L. YUNG, and A. O. NIER (1976)
Science 194, 1295-1298
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Temperatures of the Martian Surface and Atmosphere: Viking Observation of Diurnal and Geometric Variations.
H. H. Kieffer, H. H. KIEFFER, P. R. CHRISTENSEN, T. Z. MARTIN, E. D. MINER, and F. D. PALLUCONI (1976)
Science 194, 1346-1351
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