论文标题
作用在椭圆形地幔上的扭转Alfvén模式的压力扭矩
Pressure torque of torsional Alfvén modes acting on an ellipsoidal mantle
论文作者
论文摘要
我们研究了流体芯与快速旋转的行星芯中磁性水动力模式产生的固体地幔之间的压力扭矩。开发了核心流体动力学的二维还原模型，以解释非球形核心掩体边界。这种准地藻模型的简化基于沿旋转轴的流体速度的赤道成分的不变性的假设。我们使用此模型来研究和量化线性模式的轴向扭矩，重点是椭圆形中的扭转alfvén模式（TM）。我们验证这些模式的周期不取决于旋转频率。此外，它们具有角动量，导致作用在地幔上的净压扭矩。该扭矩与赤道椭圆度线性缩放。我们估计，对于此处计算的TM，与地幔相结合的TM太弱了，无法解释地球当天的变化。
We investigate the pressure torque between the fluid core and the solid mantle arising from magnetohydrodynamic modes in a rapidly rotating planetary core. A two-dimensional reduced model of the core fluid dynamics is developed to account for the non-spherical core-mantle boundary. The simplification of such a quasi-geostrophic model rests on the assumption of invariance of the equatorial components of the fluid velocity along the rotation axis. We use this model to investigate and quantify the axial torques of linear modes, focusing on the torsional Alfvén modes (TM) in an ellipsoid. We verify that the periods of these modes do not depend on the rotation frequency. Furthermore, they possess angular momentum resulting in a net pressure torque acting on the mantle. This torque scales linearly with the equatorial ellipticity. We estimate that for the TM calculated here topographic coupling to the mantle is too weak to account for the variations in the Earth's length-of-day.
