THREE-DIMENSIONAL MODELING OF HOT JUPITER ATMOSPHERIC FLOWS
THREE-DIMENSIONAL MODELING OF HOT JUPITER ATMOSPHERIC FLOWS
复制标题
热木星大气流动的三维建模
DOI：
10.1088/0004-637x/714/2/1334
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
K. Menou
中科院分区：
文献类型：
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作者：
E. Rauscher;K. Menou
我们利用雷丁大学的中间大气环流模型，建立了一个从200巴延伸到1毫巴的三维热木星模型。我们的水平光谱分辨率为T31(相当于一个48×96的网格)，具有33个对数间隔的垂直能级。辐射强迫采用简化的牛顿格式。我们采用了与Cooper&Showman的HD 209458B模型几乎相同的物理设置，以便于直接进行模型间比较。我们的结果与他们的大致一致，但也出现了显著的差异。大气流动的特征是赤道超高速急流、跨音速风速和远离白天的热量向东平流。我们在行星日侧发现了一个动态诱导的逆温(“平流层”)，并发现行星边缘的温度与当地的辐射平衡值有系统地不同，这是凌日光谱解释的一个潜在的偏差来源。虽然我们的大气模型与Cooper&Showman的大气模型几乎相同，并且我们求解相同的气象方程，但我们使用不同的算法方法，光谱隐式和网格显式，众所周知，这些方法在地球模拟环境中产生完全一致的结果。这里发现的模型差异表明，一种或两种数值方法并不能忠实地捕捉到在炎热的木星背景下工作的所有大气动力学。我们强调了我们的模型中出现了类似激波的特征，很像Showman等人最近报道的那样，并建议像Goodman强调的那样，在热木星大气模型中可能需要改进能量守恒的表示。
We present a three-dimensional hot Jupiter model, extending from 200 bar to 1 mbar, using the Intermediate General Circulation Model from the University of Reading. Our horizontal spectral resolution is T31 (equivalent to a grid of 48 × 96), with 33 logarithmically spaced vertical levels. A simplified (Newtonian) scheme is employed for the radiative forcing. We adopt a physical setup nearly identical to the model of HD 209458b by Cooper & Showman to facilitate a direct model inter-comparison. Our results are broadly consistent with theirs but significant differences also emerge. The atmospheric flow is characterized by a super-rotating equatorial jet, transonic wind speeds, and eastward advection of heat away from the dayside. We identify a dynamically induced temperature inversion (“stratosphere”) on the planetary dayside and find that temperatures at the planetary limb differ systematically from local radiative equilibrium values, a potential source of bias for transit spectroscopic interpretations. While our model atmosphere is quasi-identical to that of Cooper & Showman and we solve the same meteorological equations, we use different algorithmic methods, spectral-implicit versus grid-explicit, which are known to yield fully consistent results in the Earth modeling context. The model discrepancies identified here indicate that one or both numerical methods do not faithfully capture all of the atmospheric dynamics at work in the hot Jupiter context. We highlight the emergence of a shock-like feature in our model, much like that reported recently by Showman et al., and suggest that improved representations of energy conservation may be needed in hot Jupiter atmospheric models, as emphasized by Goodman.