Publication Abstracts

Stewart 1967

Stewart, R.W., 1967: Temperature and Composition of the Martian Atmosphere. Ph.D. thesis. Columbia University.

Calculations have been carried through to determine the thermal structure of the Martian atmosphere. The primary input to these calculations is provided by the following information revealed by the radio occultation experiment aboard the Mariner IV spacecraft:

1. A surface pressure of 5±1 mb.

2. A scale height near the surface of 9±1 km.

3. Solar flux and photoionization cross section data.

Ground-based observations and laboratory experiments indicate a total Mars CO2 content of 90±27 m-atm and an upper limit of 70 cm-atm for O2. We assume: a composition of 80% CO2 and 20% N2 at the ground, a surface tmperature of 180°K, representing the temperature at the latitude of the Mariner observation; and a mean molecular mass of 40. These values are consistent with the Mariner scale height. The above data determine the gross properties of the lower atmosphere.

The temperature above the mesopause is computed from the second order form of the thermal conduction equation. Radiative losses by atomic oxygen, carbon monoxide and carbon dioxide are included, and the variation of thermal conductivity with composition is allowed for.

The principal result of the study is the temperature of the Martian exosphere as a function of the solar heating flux. This result is used to obtain the variation of the exospheric temperature over a sunspot cycle. The exospheric temperature is found to vary from 180°K at sunspot minimum to 550°K at sunspot maximum.

A study of the relative effectiveness of CO and O as radiators of the planetary thermosphere is carried out. The results of this study are independent of the atmospheric model and serve as a useful check on numerical studies. In the present model it is found that radiative cooling by O dominates at sunspot minimum and cooling by CO dominates near sunspot maximum.

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BibTeX Citation

  author={Stewart, R. W.},
  title={Temperature and Composition of the Martian Atmosphere},
  school={Columbia University},
  address={New York, N.Y.},

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RIS Citation

ID  - st06710l
AU  - Stewart, R. W.
PY  - 1967
BT  - Temperature and Composition of the Martian Atmosphere
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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