HR: 12:05h
AN: SA52A-08    [Abstracts]
TI: Towards a Classification System for Assessing Extrasolar Planet Habitability
AU: * Sohl, L E
EM: les14@columbia.edu
AF: NASA/GISS at Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: Chandler, M A
EM: mac59@columbia.edu
AF: NASA/GISS at Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: Scharf, C A
EM: caleb@astro.columbia.edu
AF: Dept. of Astronomy, 550 West 120th Street Mail Code 5246, New York, NY 10027 United States
AU: Del Genio, A
EM: adelgenio@giss.nasa.gov
AF: NASA/GISS at Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: Allison, M
EM: Michael.D.Allison@nasa.gov
AF: NASA/GISS at Columbia University, 2880 Broadway, New York, NY 10025 United States
AU: Menou, K
EM: kristen@astro.columbia.edu
AF: Dept. of Astronomy, 550 West 120th Street Mail Code 5246, New York, NY 10027 United States
AB: There is currently no quantitatively-based framework on which to focus the search for Earth-like habitable planets, or to assess the habitability of extrasolar planets already discovered. We suggest that previous assessments have been limited by an incomplete understanding of what a habitable planet could be, and that the search for habitable worlds has been overly limited. We propose to create the first quantitative guide to the habitability and observable characteristics of a broad range of extrasolar planets, using a hierarchy of numerical climate models for worlds spanning a parameter space of orbit and spin configurations, gravity, stellar parents, hydrologic cycles, and atmospheric composition. Habitability is defined, at least initially, via terrestrial analogs. We will explore these through a series of 3-D general circulation model (GCM) paleoclimate simulations, based upon available geologic data. The time slices selected represent Earth's own passage through distinct phases of habitability, from the late Archaean (2.8 Ga) through the Early Paleozoic (440 Ma); each phase reflects steps in the co-evolution of climate and life. Various impacts upon the hydrologic cycle of Earth-like worlds, such as changes in rotation rate, land/sea distribution and ocean heat transports will also be explored using generic GCM simulations at a higher resolution (2 x 2.5 degree grid). Our classification effort will then extend to non-Earth-like terrestrial bodies and to gas giants orbiting various types of stars, through the use of simplified GCMs and 1-D energy balance models (EBMs) better suited to exploration of certain conditions as superrotation, tidal lock, and non-Earth-specific radiative schemes. This array of models will not only allow us to explore a broader range of investigations, but will also permit some degree of calibration and physical understanding between the different approaches. In addition to unveiling the physical diversity of potential habitable zones and exoplanet climates, this effort will form a critical basis for the selection of candidate planets for intensive observation by future planet-finding instruments. At the same time, the project will help us to understand both the Earth and our Solar System within the much broader context of exoplanetary habitability and the potential for extrasolar life.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 3367 Theoretical modeling
DE: 5210 Planetary atmospheres, clouds, and hazes (0343)
DE: 5225 Early environment of Earth
DE: 5704 Atmospheres (0343, 1060)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005