On the variations of the solar wind magnetic field about the Parker spiral direction
On the variations of the solar wind magnetic field about the Parker spiral direction
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DOI：
10.1029/2009ja015040
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发表时间：
2010-09-09
影响因子：
2.8
通讯作者：
Borovsky, Joseph E.
中科院分区：
文献类型：
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作者：
Borovsky, Joseph E.
使用 ACE、Helios 和 OMNI2 测量，对太阳风磁场的方向矢量进行统计分析。发现了两个方向向量群体：关于帕克螺旋方向的高斯分布和各向同性群体。对各向同性总体的检查发现了喷射物、长期非帕克螺旋间隔、磁洼、日光层电流片交叉以及高斯总体的溢出。通过数值实验，探索并量化了从高斯总体到各向同性总体的球坐标溢出。 ACE 测量发现，高斯帕克螺线群的角宽度随着太阳风的速度而增加。逐年检查这两个种群的特性，没有发现明显的太阳周期趋势。在共转相互作用区域的压缩区域内，高斯帕克螺旋群的纵向宽度减小了大约两倍，而该群的横向宽度大致不变。 Helios 测量发现，越靠近太阳，高斯帕克螺线布居的角宽度就越小，各向同性分数也就越小。将太阳风结构的通量管模型与航天器测量进行比较：该模型大致符合 Helios 行为随距太阳距离的变化，并且该模型大致符合同转相互作用区域压缩中的 ACE 行为。
Using ACE, Helios, and OMNI2 measurements, the direction vectors of the solar wind magnetic field are statistically analyzed. Two populations of direction vectors are found: a Gaussian distribution about the Parker spiral direction and an isotropic population. Examination of the isotropic population finds ejecta, long-duration non-Parker spiral intervals, magnetic depressions, heliospheric-current-sheet crossings, and spillover from the Gaussian population. Via numerical experiments, spillover in spherical coordinates from the Gaussian population into the isotropic population is explored and quantified. ACE measurements find that the angular width of the Gaussian Parker spiral population increases with solar wind speed. Examining the properties of the two populations year by year, no clear solar-cycle trends are found. Inside the compression regions of corotating interaction regions, the longitudinal width of the Gaussian Parker spiral population decreases by about a factor of two, while the latitudinal width of that population is approximately unchanged. Helios measurements find that the angular width of the Gaussian Parker spiral population decreases closer to the Sun, and the isotropic fraction decreases. The flux tube model of the solar wind structure is compared with spacecraft measurements: the model approximately agrees with the Helios behavior versus the distance from the Sun, and the model approximately agrees with the ACE behavior in the corotating interaction region compressions.