MODEL FOR THE COMPOSITION OF THE MARTIAN ATMOSPHERE.

A model is calculated for the globally averaged density distributions of the constituents of the Martian atmosphere from the surface to a height of 250 km. Improved data are used on the turbulent mixing coefficient as a function of height, and the distribution of temperature and the chemical and photochemical reaction rates. The model representation closely fits existing measurements of the densities of certain constituents. An analysis is made of how the composition depends on possible long-period variations in temperature, humidity, and turbulent mixing. The relative contribution of various catalytic cycles is ascertained, as well as the important role of excited O(**1D) atoms.