HR: 1340h
AN: P13A-0975    [Abstracts]
TI: Modeling the Evolution of Snowpacks on Mars
AU: * Zent, A P
EM: Aaron.P.Zent@nasa.gov
AF: NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035 United States
AU: Sutter, B
EM: bsutter@mail.arc.nasa.gov
AF: SETI Institute, 515 Whisman, Mountain View, CA 94043 United States
AB: A radiative-convective atmosphere model has been coupled with a numerical model of snowpack evolution in order to evaluate the factors that can lead to snowpack melting on Mars. The model accounts for snowpack temperature, melting, transport of liquid and water vapor, ablation, densification and grain metamorphosis. The model allows us to explore the importance of latitude, ambient relative humidity, hillside slope and azimuth, variations in the optical properties and abundance of admixed martian dust, and wind speed. The model also allows us to vary the orbital parameters, atmospheric pressure, and solar irradiance to simulate snowpack evolution over geologic history. Although snowmelt has been argued to account for Mars gully formation (Christensen, 2002), it has been argued by Heldmann and Mellon (2004) that melting is an unlikely origin, based on the form and distribution of gullies. The model presented here will be used to determine the minimum conditions necessary for melting in a variety of gully configurations, and those requirements can be compared to likely climate scenarios to evaluate the plausibility of a melt origin. Particular attention will be focused on determining the dust abundance and distribution required for melting, based upon realistic optical constants for Mars surficial dust. In addition, the potential role of topography in shielding the snowpack from radiation to the Martian sky will be addressed. Initial dust-free, planar geometry simulations have yet to identify any circumstances in which melting is likely, as expected. Sublimation, ablation is the mechanism by which snowpacks disappear
DE: 1833 Hydroclimatology
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting