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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.