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arXiv 1208.0126astro-ph.EP
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热对流层的大气环流:对初始条件不敏感

Atmospheric circulation of hot Jupiters: insensitivity to initial conditions

Beibei Liu, Adam P. Showman

摘要:

对热彗星的持续描述激发了各种各样的大气环流模型。这种模式必须从一个假定的初始状态开始进行积分,该初始状态通常被认为是无风的静止状态。在这里,我们调查的敏感性热木星大气环流模型的初始条件。我们考虑两类模型-浅水模型,这已被证明是成功的,在这些行星上发挥的动力学机制,和完整的三维模型类似的文献中正在探索。模型初始化与纬向射流,我们探讨了各种不同的初始射流配置文件。我们证明,在这两类模型中,最终的平衡状态是独立的初始条件-只要摩擦阻力附近的域的底部和/或与指定的行星内部的相互作用包括在内,使大气可以调整角动量随着时间的推移相对于内部。当包括这样的机制时,否则以非常不同的初始条件初始化的相同模型都收敛到相同的统计稳态。在某些情况下,模型表现出适度的时间变异性;这种变异性导致统计稳态的随机波动,但我们强调,即使在这些情况下,统计稳态本身并不依赖于初始条件。虽然热木星环流模型的结果取决于辐射强迫和摩擦阻力的细节,其中的方面仍然不确定,我们的结论是,初始条件的规格是不是一个来源的不确定性,至少在目前大多数模型中探索的参数范围。

英文摘要:

The ongoing characterization of hot Jupiters has motivated a variety of circulation models of their atmospheres. Such models must be integrated starting from an assumed initial state, which is typically taken to be a wind-free, rest state. Here, we investigate the sensitivity of hot-Jupiter atmospheric circulation models to initial conditions. We consider two classes of models--shallow-water models, which have proven successful at illuminating the dynamical mechanisms at play on these planets, and full three-dimensional models similar to those being explored in the literature. Models are initialized with zonal jets, and we explore a variety of different initial jet profiles. We demonstrate that, in both classes of models, the final, equilibrated state is independent of initial condition--as long as frictional drag near the bottom of the domain and/or interaction with a specified planetary interior are included so that the atmosphere can adjust angular momentum over time relative to the interior. When such mechanisms are included, otherwise identical models initialized with vastly different initial conditions all converge to the same statistical steady state. In some cases, the models exhibit modest time variability; this variability results in random fluctuations about the statistical steady state, but we emphasize that, even in these cases, the statistical steady state itself does not depend on initial conditions. Although the outcome of hot-Jupiter circulation models depend on details of the radiative forcing and frictional drag, aspects of which remain uncertain, we conclude that the specification of initial conditions is not a source of uncertainty, at least over the parameter range explored in most current models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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