On the secular variation of Saturn's magnetic field
On the secular variation of Saturn's magnetic field
复制标题
DOI：
10.1016/j.pepi.2015.11.002
复制
发表时间：
2016-01-01
影响因子：
2.3
通讯作者：
Bloxham, J.
中科院分区：
文献类型：
--
作者：
Stanley, S.;Bloxham, J.
土星近乎轴对称的磁场给发电机理论带来了一个问题，需要一种特殊的机制来使磁场轴对称。主要的解释是，发电机源区域周围的稳定分层层中的纬向流减弱了场的非轴对称分量。在这里，我们证明了这种轴对称过程的一个重要理论结果：场分量的长期变化必须非常缓慢。观测证据表明土星可能确实属于这种情况。此外，我们还提出了数值发电机模拟，再现了观察到的土星磁场的轴对称性，并证实了高度轴对称模型中极慢的长期变化率。这一结果的结果是，我们可以利用轴对称场的时间变化来了解卡西尼号现有数据中未观察到的非轴对称场分量。 (C) 2015 Elsevier B.V. 保留所有权利。
Saturn's nearly axisymmetric magnetic field poses a problem for dynamo theory, requiring that a special mechanism operates to axisymmetrize the field. The leading explanation is that zonal flows in a stably stratified layer surrounding the dynamo source region attenuate the non-axisymmetric components of the field. Here we demonstrate an important theoretical consequence of this axisymmetrization process: the secular variation of the field components must be extremely slow. Observational evidence suggests this may indeed be the case for Saturn. In addition, we present numerical dynamo simulations that reproduce the observed axisymmetry of Saturn's field and confirm the extremely slow secular variation rates in highly axisymmetric models. A consequence of this result is that we can use time variation of the axisymmetric field to learn about the non-axisymmetric field components which are not observed in present data from Cassini. (C) 2015 Elsevier B.V. All rights reserved.