HR: 1340h
AN: P13A-0138    [Abstracts]
TI: Global Distribution of Water Vapor in the Martian Atmosphere: Results from TES
AU: * Krelove, K
EM: kara.krelove@asu.edu
AF: Arizona State University, Mars Space Flight Facility Moeur Building, Rm 131, Tempe, AZ 85287
AU: Christensen, P
EM: phil.christensen@asu.edu
AF: Arizona State University, Mars Space Flight Facility Moeur Building, Rm 131, Tempe, AZ 85287
AU: Smith, M
EM: Michael.D.Smith@nasa.gov
AF: NASA GFSC, 8800 Greenbelt Road, Greenbelt, MD 20771
AB: Atmospheric water vapor is an integral part of the water cycle on Mars, just as on Earth, and is the one that we can study most easily. Following methods laid out by Smith ( Geophys. Res. Lett. v28, n22, 2001), this study used data from the TES instrument onboard the MGS orbiter to calculate a brightness temperature ratio of water vapor to the background atmosphere, a ratio that changes in quadratic proportion to the column depth of water vapor present. Multiple spectral bands from 200 to 400 cm^-1 were used in order to avoid most interference from dust and water ice in the Martian atmosphere. Smith looked primarily at annual and interannual variability in longitude-averaged vapor; this study expands the viewpoint to examine in detail the global distribution of water vapor over a single Martian year. Due to elevation-related effects in the column depth calculation, data were mapped in both raw form, and adjusted for elevation differences. It was found that water vapor is not evenly distributed at a given latitude; rather, there are significant longitudinal variations. The most notable variations occur at equatorial latitudes, from 30°N to 30°S, but the effects are not restricted to these latitudes. Although there is no good evidence of extremely localized (order of a few km) sources of water vapor, there is evidence quite suggestive of large-scale regolith exchange, particularly in but not restricted to the southern hemisphere, poleward of 45°S, and possibly in Arabia Terra. There are also patterns to suggest that there is a net loss of water vapor to the north, in contradiction to some MCGM results; however, this will require further study. Overall, elevation and seasonal air temperature/wind changes exhibit the strongest controls over water vapor column depth; thermal inertia has a lesser role. Albedo does not appear to independently influence the water vapor distribution.
DE: 5405 Atmospheres (0343, 1060)
DE: 5445 Meteorology (3346)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005