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C. D. Parkinson (Caltech/JPL), M. I. Richardson (Caltech), J. C. McConnell (York University), Y. L. Yung (Caltech), V. S. Meadows (Caltech/JPL)
A new technique has been developed for the treatment of hydrodynamic loss processes from planetary atmospheres utilising the Godunov method. A detailed description of a first order Godunov scheme is given by Godunov (1959), Gombosi (1984), and Leveque (2002). Solving the one-dimensional, steady state approximation becomes problematic at the distance where the outflow becomes supersonic. This method overcomes the instabilities inherent in modeling transonic conditions by solving the coupled, time dependent mass, momentum, and energy equations, instead of integrating time independent equations. We validate a preliminary model of hydrodynamic escape against simple, idealised cases (viz., steady state and isothermal conditions) showing that a robust solution obtains and then compare to existing cases in the literature (Watson et al., 1981; Kasting and Pollack, 1983; Chassefiere, 1996). A focus of this work is on observable aspects of atmospheres that may be useful for comparison between models and observations. "Close-in" hot Jupiter's provide an ideal test case because of recent observations of HD 209458b. The general tools developed here will be applied to various problems such as the early Earth and Venus, and close-in extrasolar gas giant planets and are directly applicable to modifications required for the VPL terrestrial planet models.
The author(s) of this abstract have provided an email address for comments about the abstract: chris.parkinson@jpl.nasa.gov
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.