Accession Number:

AD0627660

Title:

A MODEL FOR THE LOWER ATMOSPHERE OF MARS BASED ON MARINER IV OCCULTATION DATA,

Descriptive Note:

Corporate Author:

LOCKHEED MISSILES AND SPACE CO PALO ALTO CALIF RESEARCH LABS

Personal Author(s):

Report Date:

1965-12-01

Pagination or Media Count:

32.0

Abstract:

The Mariner IV occultation experiment has resulted in several surprising conclusions about the lower atmosphere of Mars, including very low values for the neutral properties temperature, pressure, and density and the dominance of CO2. Guided by these new results and theoretical models of the Martian atmosphere, a neutral property model has been derived which takes into account surface air temperature variation. The neutral properties up to 50 km exhibit a strong dependence on the surface temperature. Thus, it appears that the meteorology of Mars, even at the higher altitudes, depends significantly on the surface temperature distribution. An isopycnic constant density level is manifested in the model at 10 km where the density value is 5.77 x 0.000001 gmcc for surface temperatures ranging from 175K to 325K. At 50 km, the density variation for this same surface temperature range is a factor of 4. The height of the tropopause boundary between convective and radiative equilibrium regimes, taken to vary linearly with the surface temperature, is one of the principal uncertainties since the computed properties are sensitive to it. The accuracy of the model is indicated to decrease with altitude, especially above 30 km where the effects of CO2 photochemistry, doppler broadening, and the departure from local thermodynamic equilibrium start to become important. Author

Subject Categories:

  • Astrophysics
  • Unmanned Spacecraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE