Atmospheric circulation of hot Jupiters: Coupled radiative-dynamical general circulation model simulations of HD 189733b and HD 209458b - AstrophysicsReportar como inadecuado




Atmospheric circulation of hot Jupiters: Coupled radiative-dynamical general circulation model simulations of HD 189733b and HD 209458b - Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We present global, three-dimensional numerical simulations of HD 189733b andHD 209458b that couple the atmospheric dynamics to a realistic representationof non-gray cloud-free radiative transfer. The model, which we call theSubstellar and Planetary Atmospheric Radiation and Circulation SPARC model,adopts the MITgcm for the dynamics and uses the radiative model of McKay,Marley, Fortney, and collaborators for the radiation. Like earlier work withsimplified forcing, our simulations develop a broad eastward equatorial jet,mean westward flow at higher latitudes, and substantial flow over the poles atlow pressure. For HD 189733b, our simulations without TiO and VO opacity canexplain the broad features of the observed 8 and 24-micron light curves,including the modest day-night flux variation and the fact that the planet-starflux ratio peaks before the secondary eclipse. Our simulations also providereasonable matches to the Spitzer secondary-eclipse depths at 4.5, 5.8, 8, 16,and 24 microns and the groundbased upper limit at 2.2 microns. However, wesubstantially underpredict the 3.6-micron secondary-eclipse depth, suggestingthat our simulations are too cold in the 0.1-1 bar region. Predicted temporalvariability in secondary-eclipse depths is ~1% at Spitzer bandpasses,consistent with recent observational upper limits at 8 microns. We also showthat nonsynchronous rotation can significantly alter the jet structure. For HD209458b, we include TiO and VO opacity; these simulations develop a hot >2000K dayside stratosphere. Despite this stratosphere, we do not reproduce currentSpitzer photometry of this planet. Light curves in Spitzer bandpasses showmodest phase variation and satisfy the observational upper limit on day-nightphase variation at 8 microns. abridged



Autor: Adam P. Showman, Jonathan J. Fortney, Yuan Lian, Mark S. Marley, Richard S. Freedman, Heather A. Knutson, David Charbonneau

Fuente: https://arxiv.org/







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