arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1006.3239physics.space-phastro-ph.SRphysics.geo-phphysics.plasm-ph
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行星际磁场小尺度起伏的关联函数

Correlation functions of small-scale fluctuations of the interplanetary magnetic field

Z. Németh, G. Facskó, E. A. Lucek

摘要:

行星际磁场具有复杂的时空变化。单个航天器的测量只揭示了这个丰富的四维现象的一维部分。对四个星团航天器的多点测量为研究该区域的时空结构提供了一个独特的工具。利用聚类数据,我们确定了波动的三维关联函数。利用关联函数可以描述和测量场的变化。我们的结果可以用来验证理论预测,了解太阳风湍流的形成和性质。我们发现,相关长度变化超过近六个数量级。IMF湍流表现出显着的各向异性与两个不同的人口。在一定的时间间隔内,相关椭圆的三个轴的比率为1/2.2/6,而在剩余的时间内,我们发现沿一个轴的极高的相关性。我们发现有利的方向的相关椭球体的取向。

英文摘要:

The Interplanetary Magnetic Field shows complex spatial and temporal variations. Single spacecraft measurements reveal only a one dimensional section of this rich four dimensional phenomenon. Multi-point measurements of the four Cluster spacecraft provide a unique tool to study the spatiotemporal structure of the field. Using Cluster data we determined three dimensional correlation functions of the fluctuations. By means of the correlation function one can describe and measure field variations. Our results can be used to verify theoretical predictions, to understand the formation and nature of solar wind turbulence. We found that the correlation length varies over almost six orders of magnitude. The IMF turbulence shows significant anisotropy with two distinct populations. In certain time intervals the ratio of the three axes of the correlation ellipse is 1/2.2/6 while in the remaining time we found extremely high correlation along one axis. We found favoured directions in the orientation of the correlation ellipsoids.

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