VERTICAL DISTRIBUTION OF WATER-VAPOR AND MARS MODEL LOWER AND MIDDLE ATMOSPHERE

Observations and model calculations of water vapor diffusion suggest that about half the amount of water vapor is distributed with constant mixing ratio in the Martian atmosphere, the other half is the excess water vapor in the lower troposphere. During 24 hr the total content of water vapor may vary by a factor of two. The eddy diffusion coefficient providing agreement between calculations and observations is K = (3-10) × 106 cm2 sec-1 in the troposphere. An analytical expression is derived for condensate density in the stratosphere in terms of the temperature profile, the particle radius r, and K. The calculations agree with the Mars 5 measurements for r = 1.5 μm, condensate density 5 × 10-12 g/cm3 in the layer maximum at 30 to 35 km, condensate column density 7 × 10-6 cm-2, K = (1-3) × 106 cm2 sec-1, and the temperature profile T = 185 - 0.05z - 0.01z2 at 20 to 40 km. Condensation conditions yield a temperature of 160°K at 60 km in the evening; the scale height for scattered radiation yields T = 110°k at 80 to 90 km. The Mars model atmosphere has been developed up to 125 km. © 1979.