ISEE 1 & 2 observations of the oscillating magnetopause
ISEE 1 & 2 observations of the oscillating magnetopause
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DOI：
10.1029/gl015i008p00744
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发表时间：
1988-08
影响因子：
5.2
通讯作者：
P. Song;R. Elphic;C. Russell
中科院分区：
文献类型：
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作者：
P. Song;R. Elphic;C. Russell
用ISEE 1和2上的磁力计观测到的多次磁层顶交叉的检查使我们能够确定周期大于约2分钟的磁层顶表面波振荡的振幅及其与纬度、当地时间和行星际磁场方向（IMF）的依赖关系。磁层顶向南的振荡比向北的振荡更强。当国际货币基金组织向南移动时，振荡幅度随太阳次点角度的增加而增大，这表明重联相关现象可以在磁层顶产生表面波。当IMF向北时，振荡不随距离太阳次点的距离而增长，这与开尔文-亥姆霍兹（K-H）不稳定性的预期增长相反。对太阳风动压谱的研究表明，太阳风动压波动可能是观测到的所有北向IMF边界振荡的原因。因此，K-H不稳定性在造成日侧磁层顶表面波时最多只起很小的作用，其周期超过约2分钟。
Examination of multiple magnetopause crossings observed with the magnetometers on ISEE 1 and 2 has allowed us to determine the amplitude of the oscillation of surface waves on the magnetopause with periods greater than about 2 minutes and its dependence on latitude, local time and direction of the interplanetary magnetic field (IMF). The magnetopause is more oscillatory for southward IMF than for northward IMF. When the IMF is southward, the amplitude of the oscillation increases with increasing angle from the subsolar point, which suggests that reconnection-related phenomena can generate surface waves on the magnetopause. When the IMF is northward, the oscillation does not grow with distance from the subsolar point, which is contrary to the expected growth of the Kelvin-Helmholtz (K-H) instability. A study of the spectrum of the solar wind dynamic pressure shows that solar wind pressure fluctuations may cause all of the observed boundary oscillations for northward IMF. Thus the K-H instability plays at most a very minor role in causing the surface waves on the dayside magnetopause with periods longer than about 2 minutes.