2002 Annual Science Report
University of Washington Reporting | JUL 2001 – JUN 2002
Connection Between Orbit, Climate and Surface Modification Processes on Mars
In a review paper (Leovy, 2001), we show that models of the Martian climate system (general circulation models, GCMs) and observations are in good agreement and we suggest that GCMs can be used to explore the long-term distribution of ablation and deposition of fine particles over the Martian surface. This is an essential step for the evaluation of alternative hypotheses of the evolution of the surface, particularly the hypothesis that there was an extended early period of warm, wet climate in which most carbon dioxide was removed from the climate system as carbonate deposits. Recent GCM results suggest that regions of ablation and deposition remain remarkably stable over orbital cycles. Much of the northern plains and southern subtropics are persistent ablation regions with deposition in certain tropical regions as well as the Polar Regions. If this conclusion is correct, the northern plains are unlikely to be the hiding place for large volumes of water ice or carbonates and any large hidden volumes of water ice or carbonates must instead reside beneath much older tropical or southern hemisphere surfaces.
To explore this issue further, we have undertaken three tasks. (1) Orbital parameter variations over 1 billion years have been re-considered using software developed by Tom Quinn. Statistics of orbital parameter variations will be used as input to ablation-deposition histories generated with the aid of a GCM. (2) In collaboration with Bob Haberle at NASA Ames, we have begun to use a GCM to investigate the dependence of surface stress distributions on global mean surface pressure. Preliminary results show the expected increase of stress and ablation potential with pressure in the regions where ablation potential is high in the present climate. (3) Working with several undergraduate students, we have begun to investigate the global distribution of surface textural features that may be indicative of long-term ablation or deposition.
PROJECT MEMBERS:Conway Leovy
RELATED OBJECTIVES:Objective 8.0
Search for evidence of ancient climates, extinct life and potential habitats for extant life on Mars.
Define climatological and geological effects upon the limits of habitable zones around the Sun and other stars to help define the frequency of habitable planets in the universe.