Water vapor in the Martian atmosphere - A discussion of the Viking data

A summary of calculations describing the Martian atmosphere water vapor content based on data from the Mars Atmospheric Water Detectors carried by the Viking landers is presented. The water column has been observed to vary with season, time of day, and locality. Over 5 yr of continuous data collection has permitted modeling of the Martian year into 24 seasonal periods of planetocentric solar longitude, with gaps in the model due to the presence of dust storms. The vapor content is asymmetric pole-to-pole, but symmetric latitudinally with respect to the equator. Low elevation areas display a higher vapor content, especially with rapid height changes in nearby terrain. Dust storms reduced the total atmospheric vapor, with concentration shifts tending toward the north, from where it is expected renewed balances will be reinstated. Consideration is also given to diurnal variations, and variations due to temperature, composition, and wind velocity.