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arXiv 1402.3679astro-ph.EPphysics.flu-dynphysics.geo-ph
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快速旋转可压缩对流中的带状流标度

Zonal flow scaling in rapidly-rotating compressible convection

T. Gastine, M. Heimpel, J. Wicht

备注：
17 pages, 12 figures, 3 tables, accepted for publication in PEPI
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摘要：

木星和土星的表面风主要是纬向风。每颗行星都表现出强烈的赤道气流，两侧是高纬度的多个交替的纬向风。这些流动的渗透深度长期以来一直存在争议，仍然是一个未解决的问题。以前的旋转对流模型获得了多个高纬度带状喷流，与巨行星上的喷流相当，假设不可压缩（Boussinesq）流体，这对气体巨行星来说是不现实的。后来的可压缩旋转对流模型只得到了很少的高纬度急流，这些急流不适合于标度分析。在这里，我们提出了3-D数值模拟的可压缩对流在快速旋转球壳。为了探索高纬度纬向喷流的形成和缩放，我们考虑具有强径向密度变化和Ekman数范围的模型，同时保持土星的纬向流Rossby数特征。所有的模拟结果都显示出切向圆柱体外有一个很强的近赤道喷流。在低埃克曼数时，切向圆柱体内的每个半球中形成几个交替的射流。为了分析我们的数值模型和木星和土星的射流缩放，我们扩展莱茵缩放的基础上的地形$β$参数，这是以前适用于不可压缩流体的球壳，可压缩流体。喷流宽度预测的修改后的莱茵河长度被认为是在相对较好的协议与我们的数值模式的结果和云跟踪观测木星和土星。

英文摘要：

The surface winds of Jupiter and Saturn are primarily zonal. Each planet exhibits strong prograde equatorial flow flanked by multiple alternating zonal winds at higher latitudes. The depth to which these flows penetrate has long been debated and is still an unsolved problem. Previous rotating convection models that obtained multiple high latitude zonal jets comparable to those on the giant planets assumed an incompressible (Boussinesq) fluid, which is unrealistic for gas giant planets. Later models of compressible rotating convection obtained only few high latitude jets which were not amenable to scaling analysis. Here we present 3-D numerical simulations of compressible convection in rapidly-rotating spherical shells. To explore the formation and scaling of high-latitude zonal jets, we consider models with a strong radial density variation and a range of Ekman numbers, while maintaining a zonal flow Rossby number characteristic of Saturn. All of our simulations show a strong prograde equatorial jet outside the tangent cylinder. At low Ekman numbers several alternating jets form in each hemisphere inside the tangent cylinder. To analyse jet scaling of our numerical models and of Jupiter and Saturn, we extend Rhines scaling based on a topographic $β$-parameter, which was previously applied to an incompressible fluid in a spherical shell, to compressible fluids. The jet-widths predicted by this modified Rhines length are found to be in relatively good agreement with our numerical model results and with cloud tracking observations of Jupiter and Saturn.

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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