Quasi‐periodic modulations of the Jovian magnetotail
Quasi‐periodic modulations of the Jovian magnetotail
复制标题
木星磁尾的准周期调制
DOI：
10.1029/98gl00861
复制
发表时间：
1998
影响因子：
5.2
通讯作者：
D. Williams
中科院分区：
文献类型：
--
作者：
J. Woch;N. Krupp;A. Lagg;B. Wilken;S. Livi;D. Williams
利用木星磁尾中伽利略轨道C9上的高能粒子探测器进行的测量表明，由于行星自转，高能离子强度存在明显的准周期变化，这些变化叠加在众所周知的10小时调制上。强度的变化与粒子能谱和等离子体流型的变化有关。它们显然是时间性质的，而不是航天器穿过周期性分离的空间结构的结果。调制周期约为3天。这种振荡在整个中磁尾区域(20-80rJ)最为明显，然而，即使在深尾区，这种振荡似乎也会持续下去。调制的幅度取决于粒子能量。测量到的最高能量(约1 MeV)显示出最强的变化。在伽利略的其他轨道上也观察到了具有类似周期的高能粒子特征。这些调制的原因尚不清楚；然而，可以推测它们对应于木星磁尾的两个基本状态之间的准周期转变，这两个状态的发生具有木星磁层固有的时间常数。
Measurements with the Energetic Particles Detector (EPD) on Galileo orbit C9 in the Jovian magnetotail revealed the existence of distinct quasi‐periodic variations of energetic ion intensities which are superimposed on the well‐known 10‐hour modulations due to the planetary rotation. The intensity variations are associated with changes of the particle energy spectra and the plasma flow pattern. They are clearly of temporal nature and not the consequence of the spacecraft passing through periodically separated spatial structures. The modulation period is about 3 days. The oscillations are most pronounced throughout the middle magnetotail regime (20 to 80 RJ), however, seem to persist even in the deep tail region. The amplitude of the modulation is dependent on the particle energy. The highest energies measured (about 1 MeV) show the strongest variations. Energetic particle features with similar periodicity are observed on other Galileo orbits as well. The cause of these modulations is unclear; however, it may be speculated that they correspond to a quasi‐periodic transition between two basic states of the Jovian magnetotail which occur with a time constant inherent to the Jovian magnetosphere.