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arXiv 1306.1899astro-ph.SR
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太阳风速度的能见度图分析

Visibility graph analysis of solar wind velocity

Vinita Suyal, Awadhesh Prasad, Harinder P. Singh

摘要:

分析了1998-2012年和1975-1983年期间先进成分探测器(ACE)和太阳神号探测器分别获得的太阳风速度的现场测量结果。这些数据主要分别属于第23太阳活动周(1996-2008)和第21太阳活动周(1976-1986)。我们使用有向水平可见图(Directed Horizontal Visibility graph,DHVg)算法并估计一个图泛函,即度距离(degree distance,D)作为Kullback-Leibler散度(KLD)的参数来理解太阳风时间序列的时间不可逆性。我们估计了这些时间序列在太阳活动周期的不同阶段的度距离不可逆性参数。首先对已知的动力学数据建立不可逆性参数,然后将其应用于太阳风速度时间序列。据观察,太阳风速度波动的不可逆性在0.3天文单位(太阳神数据)和1天文单位(ACE数据)表现出类似的行为。此外,它在太阳活动周期的不同阶段发生变化。

英文摘要:

We analyze in situ measurements of solar wind velocity obtained by Advanced Composition Explorer (ACE) spacecraft and Helios spacecraft during the years 1998-2012 and 1975-1983 respectively. The data belong to mainly solar cycle 23 (1996-2008) and solar cycle 21 (1976-1986) respectively. We use Directed Horizontal Visibility graph (DHVg) algorithm and estimate a graph functional, namely, the degree distance (D) as the Kullback-Leibler divergence (KLD) argument to understand time irreversibility of solar wind time series. We estimate this degree distance irreversibility parameter for these time series at different phases of solar activity cycle. Irreversibility parameter is first established for known dynamical data and then applied for solar wind velocity time series. It is observed that irreversibility in solar wind velocity fluctuations show similar behaviour at 0.3 AU (Helios data) and 1 AU (ACE data). Moreover it changes over the different phases of solar activity cycle.

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