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arXiv 2006.03285physics.space-phphysics.plasm-ph
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内日球层磁场涨落的标度性质

On the Scaling Properties of Magnetic Field Fluctuations Through the Inner Heliosphere

Tommaso Alberti, Monica Laurenza, Giuseppe Consolini, Anna Milillo, Maria Federica Marcucci, Vincenzo Carbone, Stuart D. Bale

摘要:

虽然已经利用来自若干空间飞行任务的数据对行星际磁场可变性进行了广泛的实地研究,但新发射的飞行任务提供了高分辨率测量并接近太阳,为研究太阳系最内层的多尺度可变性提供了可能性。本文利用帕克太阳探测器的观测资料,研究了不同日心距下太阳风磁场波动的标度特性。结果表明,在距离接近说0.4 au的一个明确的过渡。靠近太阳的涨落显示出f^-3/2的频率功率谱和规则的标度性质,而距离大于0.4 au的涨落显示出f^-5/3的柯尔莫哥洛夫谱,并具有反常标度的特征。观测到的湍流的统计特性表明,太阳风磁波动,在远离太阳的后期阶段,表现出典型的湍流的多重分形行为,并通过湍流描述,而在早期阶段,当离开日华,这些属性的故障被观察到,从而显示出统计单分形的全球自相似性。从物理上讲,在太阳附近观察到的崩溃应该是由于具有规则统计的湍流,或者是由于存在强烈的随机波动,这些波动能够抵消存在异常标度所必需的相关性。

英文摘要:

Although the interplanetary magnetic field variability has been extensively investigated in situ by means of data coming from several space missions, the newly launched missions providing high-resolution measures and approaching the Sun, offer the possibility to study the multiscale variability in the innermost solar system. Here by means of the Parker Solar Probe measurements we investigate the scaling properties of solar wind magnetic field fluctuations at different heliocentric distances. The results show a clear transition at distances close to say 0.4 au. Closer to the Sun fluctuations show a f^-3/2 frequency power spectra and regular scaling properties, while for distances larger than 0.4 au fluctuations show a Kolmogorov spectrum f^-5/3 and are characterized by anomalous scalings. The observed statistical properties of turbulence suggests that the solar wind magnetic fluctuations, in the late stage far form the Sun, show a multifractal behaviour typical of turbulence and described through intermittency, while in the early stage, when leaving the solar corona, a breakdown of these properties are observed, thus showing a statistical monofractal global self-similarity. Physically the breakdown observed close to the Sun should be due either to a turbulence with regular statistics or to the presence of intense stochastic fluctuations able to cancel out correlations necessary for the presence of anomalous scaling.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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