HR: 0800h
AN: P31C-0553    [Abstracts]
TI: Zero Obliquity Studies of Heat Transport in the Martian Paleo-climate
AU: * Soto, A
EM: asoto@caltech.edu
AF: California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125, United States
AU: Mischna, M A
EM: michael.a.mischna@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Richarson, M I
EM: mir@gps.caltech.edu
AF: California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125, United States
AB: Global-mean climate models of the Martian atmosphere have predicted that early in Martian history, and for a range of initial total CO₂ inventories, the atmosphere heat transport would be insufficient to prevent the formation of year-round CO₂ polar caps. As a consequence of cap formation, the atmosphere would collapse to a vapor pressure, or cap-buffered, state. If Mars were trapped in a collapsed state for most of its planetary history, the amount of time available for physical and chemical weathering would be, as a result, greatly limited. Predictions of atmospheric collapse in the extant global-mean climate models involves representation of an inherently three-dimensional, time varying process—heat transport—in terms of a single, globally uniform parameterization. This parameterization is unavoidably the weakest link in any low-order (0-D and 1-D) atmospheric evolution model, though its proper representation is only of critical importance when the atmosphere is near a significant transition, such as the threshold for collapse. Using a global climate model, MarsWRF, we investigate the details of the three-dimensional, time varying heat transport at the threshold for atmospheric collapse. To definitively address whether pole-ward atmospheric heat transport can, alone, prevent collapse, the most illuminating experiment is one at 0° obliquity. In this situation, solar heating near the poles tends to zero, and condensation cannot be prevented in the absence of transport, regardless of the atmospheric thickness and greenhouse effect. This investigation allows us to determine the validity of the heat transport parameterizations used by global-mean climate models, particularly with regard to atmospheric collapse.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 5210 Planetary atmospheres, clouds, and hazes (0343)
DE: 5405 Atmospheres (0343, 1060)
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting