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2005 Annual Science Report

Virtual Planetary Laboratory (JPL/CalTech) Reporting  |  JUL 2004 – JUN 2005

Climate Model for Extrasolar Terrestrial Planets

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

We developed a one-dimensional (1-D) climate model to simulate terrestrial planetary environments. A 1-D model that focuses on the physical processes governing the vertical structure and composition of the surface/atmosphere system was chosen as the first step in this investigation because the disk averaged spectrum of a planet is strongly influenced by the vertical distribution of temperature, absorbing gases, and airborne particles. Radiative heating and cooling rates are generated with the Spectral Mapping Atmospheric Radiative Transfer model [Meadows and Crisp, 1996; Crisp, 1997]. This model describes solar and thermal radiation fields in realistic, vertically-inhomogeneous, scattering, absorbing and emitting atmospheres. The vertical convective heat and volatile transport is simulated by a mixing length formulation from a state-of-the-art planetary boundary layer model [Savijarvi, 1998]. Diffusive heat transport within the surface and near-surface atmosphere is simulated by a multi-layer vertical heat diffusion model [Sertorio and Tinetti, 2002]. The Community Aerosol and Radiation Model for Atmospheres [Ackerman, et al., 1995; Jensen, et al., 1994; Toon, et al., 1988] is used to simulate airborne particle nucleation, condensation, evaporation, coagulation, and precipitation for active volatile species or passive aerosols (dust). This model has been used extensively to study clouds on Earth [Ackerman et al. 1995; Jensen and Pfister, 2004; Fridlind et al., 2004]. It has also been applied to the atmospheres of Venus [James, et al., 1997], Mars [Colaprete, et al., 2003; Michelangeli, et al., 1993], and Titan [Barth and Toon, 2004]. The VPL climate model is currently being validated by simulating the environments of terrestrial planets in our solar system. This coming year, it will be used to simulate radiative-convective-conductive equilibrium environments for a range of plausible extrasolar planetary environments.

    David Crisp David Crisp
    Project Investigator
    John Armstrong

    Giovanna Tinetti

    Objective 1.1
    Models of formation and evolution of habitable planets

    Objective 1.2
    Indirect and direct astronomical observations of extrasolar habitable planets

    Objective 7.2
    Biosignatures to be sought in nearby planetary systems