HR: 14:10h
AN: P32B-03 INVITED     [PDF]
TI: Progress in General Circulation Modeling of Recent Climate Change on Mars
AU: * Haberle, R M
EM: Robert.M.Haberle@nasa.gov
AF: NASA/Ames Research Center, Space Science Division MS 245-3, Moffett Field, CA 94035 United States
AB: The Mars Global Surveyor and Odyssey spacecraft reveal evidence that Mars may have experienced significant climate change in the recent past (10$^{5}$ - 10$^{8}$ My). Examples include gullies, cold-based tropical glaciers, paleolakes, youthful near-surface ice, and recent localized heavy erosion. Except for the gullies and erosion, the evidence for recent climate changes requires ice and/or liquid water at low latitudes. An obvious question, therefore, is how is it possible for ice and/or liquid water to exist at low latitudes which is not possible in the present climate system? Possible mechanisms for recent climate change are volcanism, impacts, polar wander, solar variability, and orbital changes. Of these, orbital changes are the least controversial and most widely accepted mechanism for climate change. Jakosky and Carr (1985) used simple scaling arguments to suggest that at high obliquity water evaporating from the north polar cap would be transported southward by the general circulation and precipitate out at low latitudes forming tropical ice deposits. General circulation models have since confirmed this prediction. However the location and abundance of the GCM-predicted deposits varies from model to model for a given orbital configuration. The reason for this variability is probably related to how the processes that control the water cycle are represented in the models. Thus far, the models run for these high obliquity cases have simple representations of cloud microphysical processes, and totally ignore the radiative effects of water vapor and clouds. Regolith exchange and dust/ice interactions are also neglected. This talk will review the current status of general circulation modeling of recent climate change and the directions future efforts are headed towards. Reference: Jakosky, B.M., and M.H. Carr (1985). Nature, 315, 559-561.
DE: 3319 General circulation
DE: 5407 Atmospheres--evolution
DE: 5416 Glaciation
DE: 5445 Meteorology (3346)
DE: 5462 Polar regions
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting