SETI bioastro: Atmospheric Circulation of Close-In Extrasolar Giant Planets: I. Global, Barotro

From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Jul 17 2006 - 14:26:12 PDT

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    Astrophysics, abstract
    astro-ph/0607338

    From: Kristen Menou [view email]

    Date: Fri, 14 Jul 2006 16:27:37 GMT (2377kb)

    Atmospheric Circulation of Close-In Extrasolar Giant Planets: I. Global,
    Barotropic, Adiabatic Simulations

    Authors: James Y-K. Cho (QM Univ. London), Kristen Menou (Columbia), Brad
    Hansen (UCLA), Sara Seager (Carnegie/DTM)

    Comments: 47 pages, 2 Tables + 18 figures, submitted to ApJ

    We present results from a set of over 300 pseudospectral simulations of
    atmospheric circulation on extrasolar giant planets with circular orbits.
    The simulations are of high enough resolution (up to 341 total and sectoral
    modes) to resolve small-scale eddies and waves, required for reasonable
    physical accuracy. In this work, we focus on the global circulation pattern
    that emerges in a shallow, ``equivalent-barotropic'', turbulent atmosphere
    on both tidally synchronized and unsynchronized planets. A full exploration
    of the large physical and numerical parameter-space is performed to identify
    robust features of the circulation. The model is validated with Solar System
    giant planets. For extrasolar giant planets with physical parameters similar
    to \HD 209458 b --a presumably synchronized extrasolar giant planet
    representative in many dynamical respects-- the circulation is characterized
    by the following features: 1) a coherent polar vortex that revolves around
    the pole in each hemisphere; 2) a low number--typically two or three--of
    slowly-varying, broad zonal (east-west) jets that form when the maximum jet
    speed is comparable to, or somewhat stronger than, those observed on the
    planets in the Solar System; and, 3) motion-associated temperature field,
    whose detectability and variability depend on the strength of the net
    heating rate and the global root mean square wind speed in the atmosphere.
    In many ways, the global circulation is Earth-like, rather than
    Jupiter-like. However, if extrasolar giant planets rotate faster and are not
    close-in (therefore not synchronized), their circulations become more
    Jupiter-like.

    http://arxiv.org/abs/astro-ph/0607338


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