Effects of compressibility on driving zonal flow in gas giants
Effects of compressibility on driving zonal flow in gas giants
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DOI：
10.1016/j.icarus.2012.03.018
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发表时间：
2012-05-01
期刊：
影响因子：
3.2
通讯作者：
Wicht, J.
中科院分区：
文献类型：
--
作者：
Gastine, T.;Wicht, J.
在气态巨行星表面观察到的带状结构与方向与纬度交替的强纬向风有关。利用非弹性近似下可压缩对流的三维数值模拟，探讨了快速旋转球壳中纬向风的性质。由于该模型仅限于电绝缘的外壳，因此我们忽略了磁效应。对不同密度尺度高度和瑞利数的系统参数研究可以探索对流和纬向射流对这些参数的依赖，并推导出尺度定律。虽然密度分层影响局地气流幅值和对流尺度，但全球量和纬向喷流特性与密度分层基本无关。区向射流由雷诺应力维持，雷诺应力依赖于区向流和圆柱径向流分量之间的相关性。随着超临界度的增加，这种相关性的逐渐丧失阻碍了我们所有的模拟，并解释了为什么额外的压缩涡度源几乎不影响纬向流动。所有这些共同的特征可以解释为什么以前的Boussinesq模型已经成功地再现了气态巨行星中带状喷流的形态。(c) 2012 Elsevier Inc.版权所有。
The banded structures observed on the surfaces of the gas giants are associated with strong zonal winds alternating in direction with latitude. We use three-dimensional numerical simulations of compressible convection in the anelastic approximation to explore the properties of zonal winds in rapidly rotating spherical shells. Since the model is restricted to the electrically insulating outer envelope, we therefore neglect magnetic effects.A systematic parametric study for various density scaleheights and Rayleigh numbers allows to explore the dependence of convection and zonal jets on these parameters and to derive scaling laws.While the density stratification affects the local flow amplitude and the convective scales, global quantities and zonal jets properties remain fairly independent of the density stratification. The zonal jets are maintained by Reynolds stresses, which rely on the correlation between zonal and cylindrically radial flow components. The gradual loss of this correlation with increasing supercriticality hampers all our simulations and explains why the additional compressional source of vorticity hardly affects zonal flows.All these common features may explain why previous Boussinesq models were already successful in reproducing the morphology of zonal jets in gas giants. (c) 2012 Elsevier Inc. All rights reserved.