Driving Saturn's magnetospheric periodicities from the upper atmosphere/ionosphere: Magnetotail response to dual sources
Driving Saturn's magnetospheric periodicities from the upper atmosphere/ionosphere: Magnetotail response to dual sources
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从高层大气/电离层驱动土星磁层周期性：磁尾对双源的响应
DOI：
10.1029/2012ja018183
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发表时间：
2012
影响因子：
--
通讯作者：
M. Kivelson
中科院分区：
文献类型：
--
作者：
X. Jia;M. Kivelson
[1]尽管土星内部磁场高度轴对称，但在土星的电磁辐射、磁扰动和粒子群中，与旋转相关的周期是明显的。虽然接近云顶的平均自转周期，但电磁周期在几年的时间尺度上略有漂移，在高纬度，南北来源的电磁周期有所不同。这种周期性的来源仍然是一个谜。所研究的模式将动量源置于高层大气/电离层，两个半球的风型以不同的速率绕自旋轴旋转，这是2005-2006年南半球夏季的典型特征，卡西尼号数据已经对其进行了广泛的分析。低海拔的震源将解释太阳风扰乱磁层流动模式后的持续相位，但可能不会产生适当的磁层响应。然而，电离层涡流驱动场向电流进入磁层的磁流体动力学模拟表明，双源几乎定量地解释了许多测量到的磁层响应。本文的重点是磁尾，在那里，该模型被证明再现了许多有良好记录的数据分析结果，包括在两个周期的每个周期都明显出现的特征，以及那些表现为具有幅度调制和相移的载波信号的特征。特别是，该模式解释了电流片的拍打和等离子体片厚度的调制，以及南北不同时期高纬度密度增强的周期性结构。
[1] Despite the high degree of axial symmetry of Saturn's internal magnetic field, rotation-associated periodicities are evident in Saturn's electromagnetic radiation, its magnetic perturbations and its particle populations. Although close to the mean rotation period of the cloud tops, the electromagnetic period drifts slightly over a time scale of years and, at high latitudes, differs for sources in the north and south. The source of the periodicity remains a mystery. The model investigated here places the momentum source in the upper atmosphere/ionosphere, with the wind patterns in the two hemispheres rotating about the spin axis at different rates typical of the 2005–2006 southern summer for which Cassini data have been extensively analyzed. A source at low altitudes would account for the persistence of phase following solar wind disruption of magnetospheric flow patterns but might not produce appropriate magnetospheric responses. However, a magnetohydrodynamic simulation in which vortical winds in the ionosphere drive field-aligned currents into the magnetosphere shows that the dual sources account nearly quantitatively for many measured magnetospheric responses. This paper focuses on the magnetotail where the model is shown to reproduce many well-documented results of data analysis including the features that appear distinctly at each of the two periods and those that appear as a carrier signal with amplitude modulation and phase shifts. In particular, the model accounts for current sheet flapping and modulation of the plasma sheet thickness and for the periodic structure of density enhancements at high latitudes at different periods in the north and the south.
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影响因子：
--
作者：
C. Arridge;K. Khurana;C. Russell;D. Southwood;N. Achilleos;M. Dougherty;A. Coates;H. Leinweber
通讯作者：
C. Arridge;K. Khurana;C. Russell;D. Southwood;N. Achilleos;M. Dougherty;A. Coates;H. Leinweber
影响因子：
5.2
作者：
Burton M
通讯作者：
Burton M
土星赤道磁层中行星周期附近的磁场振荡：振幅和相位随径向距离和当地时间的变化
DOI：
10.1029/2009ja014729
发表时间：
2010
期刊：
Space Physics
影响因子：
--
作者：
Andrews D
通讯作者：
Andrews D
土星的轴对称磁场：没有可检测到的长期变化或倾斜
影响因子：
5.3
作者：
Cao H
通讯作者：
Cao H
土星磁层中的行星周期振荡：赤道磁场振荡与土星千米辐射调制的相位关系
DOI：
10.1029/2007ja012937
发表时间：
2008
期刊：
Space Physics
影响因子：
--
作者：
Andrews D
通讯作者：
Andrews D