Properties of Solar Wind Dynamic Pressure Pulses at 1 AU during the Deep Minimum between Solar Cycles 23 and 24
Properties of Solar Wind Dynamic Pressure Pulses at 1 AU during the Deep Minimum between Solar Cycles 23 and 24
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DOI：
10.1007/s11207-015-0700-5
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发表时间：
2015-05
期刊：
影响因子：
2.8
通讯作者：
Y. Xie;P. Zuo;X. Feng;Y. Zhang
中科院分区：
文献类型：
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作者：
Y. Xie;P. Zuo;X. Feng;Y. Zhang
在太阳活动周期23和24之间的深太阳极小期期间的观测提供了一个机会，以表征极端太阳活动下太阳风动态压力脉冲（DPP）的性质。在这项研究中，我们确定了226个DPP从2008年7月至2009年6月使用自动检测算法的基础上高分辨率等离子体数据从风航天器调查的DPP的功能，在深太阳极小期。为了比较，深太阳活动极小期和前一个太阳活动极小期期间的DPPs的统计特征的相似性和差异性也进行了研究。结果表明，深太阳极小期的DPPs数量和发生率仅为前一个极小期的1/3左右，这可能是由于太阳风动压较低，动压波动较弱。然而，从统计的角度来看，没有明显的差异是明显的其他基本DPP属性在两个太阳极小期，如绝对和相对幅度的动态压力变化和持续时间的过渡区的DPP。深太阳活动极小期期间DPP的其他基本特性如下：1）动压幅值变化峰值绝对值分布在1.0 ~ 1.5 nPa之间，2）最可几的相对压力变化在0.2 ~ 0.8之间，3）DPP持续时间在150 s ~ 210 s之间呈宽峰型，平均约为171 s，（4）76.7%的DPPs可以被认为是压力平衡结构;（5）DPPs的动态压力变化主要受密度变化的影响;（6）特别是在深太阳活动极小期，相当一部分DPPs（86.7%）与行星际日冕物质抛射（ICMEs）和流相互作用区（SIRs）等大尺度太阳风瞬变有关。
Observations during the deep solar minimum between Solar Cycles 23 and 24 offer an opportunity for characterizing the nature of solar wind dynamic pressure pulses (DPPs) under extreme solar activity. In this study, we identify 226 DPPs from July 2008 to June 2009 using an automatic detection algorithm based on high-resolution plasma data from theWindspacecraft to investigate the features of DPPs during the deep solar minimum. For comparison, the similarities and differences of the statistical characteristics of the DPPs during the deep solar minimum and during the previous solar minimum are also examined. It is found that the number and the occurrence rate of DPPs during the deep solar minimum are only about one-third of those during the previous minimum, which may be attributed to lower solar wind dynamic pressure and weaker dynamic pressure fluctuations. From a statistical perspective, however, no obvious difference is apparent between the other basic DPP properties in the two solar minima, such as the absolute and relative amplitude of the dynamic pressure changes and the durations of the transition regions of DPPs. Other basic properties of the DPPs during the deep solar minimum are as follows: 1) the distribution of the absolute value of the dynamic pressure amplitude change peaks at 1.0 – 1.5 nPa, 2) the most probable relative pressure changes are 0.2 – 0.8, 3) DPP durations are broad-peaked between 150 s and 210 s with a mean of about 171 s, 4) 76.7 % of the DPPs can be considered as pressure balance structures, 5) dynamic pressure changes across DPPs are dominated by density changes, 6) specially, during the deep solar minimum, a considerable portion of DPPs, 86.7 %, are associated with large-scale solar wind transients such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs).