A dynamo driven by zonal jets at the upper surface: Applications to giant planets
A dynamo driven by zonal jets at the upper surface: Applications to giant planets
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由上表面纬向喷流驱动的发电机：在巨行星上的应用
DOI：
10.1016/j.icarus.2011.11.014
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发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
N. Schaeffer
中科院分区：
文献类型：
--
作者：
C. Guervilly;P. Cardin;N. Schaeffer
我们提出了一种发电机机制，该机制是由于旋转球壳中存在正压不稳定的纬向喷流而产生的。纬向流的剪切不稳定性以全局罗斯贝模式的形式发展，其方位角波数取决于纬向射流的宽度。我们获得了磁雷诺数大于 103 的自持磁场。我们表明罗斯贝波的传播对于发电机作用至关重要。轴对称极向磁场的振幅取决于罗斯贝模式的波数，因此取决于纬向喷流的宽度。我们讨论了这种产生巨行星磁场的发电机机制的合理性。我们的结果表明，磁场的拓扑结构与在巨行星表面观察到的纬向风轮廓之间可能存在联系。对于狭窄的类木星喷流，极向磁场由轴向偶极子主导，而对于宽的类海王星喷流，轴对称极向场较弱。
We present a dynamo mechanism arising from the presence of barotropically unstable zonal jet currents in a rotating spherical shell. The shear instability of the zonal flow develops in the form of a global Rossby mode, whose azimuthal wavenumber depends on the width of the zonal jets. We obtain self-sustained magnetic fields at magnetic Reynolds numbers greater than 103. We show that the propagation of the Rossby waves is crucial for dynamo action. The amplitude of the axisymmetric poloidal magnetic field depends on the wavenumber of the Rossby mode, and hence on the width of the zonal jets. We discuss the plausibility of this dynamo mechanism for generating the magnetic field of the giant planets. Our results suggest a possible link between the topology of the magnetic field and the profile of the zonal winds observed at the surface of the giant planets. For narrow Jupiter-like jets, the poloidal magnetic field is dominated by an axial dipole whereas for wide Neptune-like jets, the axisymmetric poloidal field is weak.
影响因子：
3.2
作者：
Redmer, Ronald;Mattsson, Thomas R.;French, Martin
通讯作者：
French, Martin