A Statistical Survey of Low‐Frequency Magnetic Fluctuations at Saturn
A Statistical Survey of Low‐Frequency Magnetic Fluctuations at Saturn
复制标题
DOI：
10.1029/2020ja028387
复制
发表时间：
2021-02
期刊：
影响因子：
--
通讯作者：
D. Pan;Z. Yao;R. Guo;B. Bonfond;Yong Wei;W. Dunn;Binzheng Zhang;Q. Zong;Xuzhi Zhou;D. Grodent;W. Wan
中科院分区：
文献类型：
--
作者：
D. Pan;Z. Yao;R. Guo;B. Bonfond;Yong Wei;W. Dunn;Binzheng Zhang;Q. Zong;Xuzhi Zhou;D. Grodent;W. Wan
低频波与磁层能量耗散过程密切相关。卡西尼号探测器探索土星的磁层超过13年，直到2017年9月，覆盖了一个完整的太阳周期。利用这一丰富的遗产数据集，我们系统地研究了土星磁层中低频波的关键物理参数，包括它们的本地时间分布和对太阳活动的依赖性。我们发现波浪活动在中午附近达到峰值。在夜面，波强度也出现在午夜前后的峰值。由于每个太阳相的当地时间范围有限，我们无法就波对太阳活动的依赖性得出确切的结论。一般来说，波功率在夜面扇区表现出向更大距离单调下降的趋势，特别是在下降阶段，这意味着低频波主要来自磁层的相对内部区域。在昼面，较强的波大多位于磁层顶附近的25Rs处。该研究显示了土星磁层中低频波的全球图像，为磁层能量如何消散到土星的极地电离层和大气层提供了重要的影响。
Low‐frequency waves are closely related to magnetospheric energy dissipation processes. The Cassini spacecraft explored Saturn's magnetosphere for over 13 years, until September 2017, covering a period of more than a complete solar cycle. Using this rich heritage data set, we systematically investigated key physical parameters of low‐frequency waves in Saturn's magnetosphere, including their local time distribution and the dependence on solar activity. We found that the wave activity peaked in the near noon sector. For the nightside, the wave intensity also appeared to peak pre and postmidnight. Due to the limited local time coverage for each solar phase, we were not able to draw a firm conclusion on the wave's dependence on solar activity. In general, the wave power showed a monotonically decreasing trend toward larger distances in nightside sectors especially during the declining phase, which implied that low‐frequency waves mainly originate from the relatively inner regions of the magnetosphere. On the dayside, stronger waves were mostly located at/within ∼25 Rs, near the magnetopause. The study shows a global picture of low‐frequency waves in Saturn's magnetosphere, providing important implications for how magnetospheric energy dissipates into Saturn's polar ionosphere and atmosphere.