Meridional Martian water abundance profiles during the 1988–1989 season

In this paper we report on measurements of the latitudinal distribution of atmospheric water vapor column abundance that were collected on 4 nights during spring and summer in the Martian southern hemisphere before and after the 1988 opposition. The profiles for early southern spring and southern autumnal equinox agree with those measured during the same season in 1977 by the Mars Atmospheric Water Detector (MAWD) on the Viking Orbiters, but the profiles during southern mid- and late summer show twice as much water in the southern hemisphere and planetwide as did the Viking MAWD. An equatorial water column abundance maximum was a relatively constant feature of the profiles acquired and 4 × 10 14 g was observed to appear and disappear at latitudes south of −30°. Based on the lack of global dust storms observed during the 1988–1989 spring and summer compared to the 1977 Viking measurements during the same period, the water abundance measurements reported in this paper represent observations in a relatively clear atmosphere.