Parameters of the Magnetic Flux inside Coronal Holes
Parameters of the Magnetic Flux inside Coronal Holes
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DOI：
10.1007/s11207-009-9433-7
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发表时间：
2009-11-01
期刊：
影响因子：
2.8
通讯作者：
Watanabe, Hiroko
中科院分区：
文献类型：
--
作者：
Abramenko, Valentyna;Yurchyshyn, Vasyl;Watanabe, Hiroko
分析了低纬冕洞(CHS)内部的磁通分布参数。根据太阳和日光层天文台(SOHO)/MDI全盘磁图和SOHO/EIT284图像对44个CHS进行的统计研究表明，净磁通量密度B(净)与相关的太阳风速V(X)无关。CHS的面积和净通量均与太阳风速相关，其空间Pearson相关系数分别为0.75和0.71。对B(Net)和V(X)之间的低相关性提出了可能的解释。观察到的非相关性可能源于磁场的结构复杂性。作为磁场复杂性的度量，填充因子f(R)被计算为空间尺度的函数。在CHS中，f(R)在2 mm以上的尺度上几乎是恒定的，这表明它是一种单一的结构组织和平稳的时间演化。Hinode SOT/SP数据的填充因子为0.04，MDI/HR数据的填充因子为0.07。Hinode的数据表明，在小于2 mm的尺度上，填充因子迅速减小，这意味着具有多重分形结构和高度间歇性、爆发式的能量释放机制。CH磁场在2毫米以上的尺度上缺乏必要的复杂性似乎是净磁通量密度似乎与太阳风速度无关的最合理的原因：太阳风加速所需的能量释放动力学似乎发生在1毫米以下的小尺度上。
The parameters of the magnetic flux distribution inside low-latitude coronal holes (CHs) were analyzed. A statistical study of 44 CHs based on Solar and Heliospheric Observatory (SOHO)/MDI full disk magnetograms and SOHO/EIT 284 images showed that the density of the net magnetic flux, B (net), does not correlate with the associated solar wind speeds, V (x) . Both the area and net flux of CHs correlate with the solar wind speed and the corresponding spatial Pearson correlation coefficients are 0.75 and 0.71, respectively. A possible explanation for the low correlation between B (net) and V (x) is proposed. The observed non-correlation might be rooted in the structural complexity of the magnetic field. As a measure of the complexity of the magnetic field, the filling factor, f(r), was calculated as a function of spatial scales. In CHs, f(r) was found to be nearly constant at scales above 2 Mm, which indicates a monofractal structural organization and smooth temporal evolution. The magnitude of the filling factor is 0.04 from the Hinode SOT/SP data and 0.07 from the MDI/HR data. The Hinode data show that at scales smaller than 2 Mm, the filling factor decreases rapidly, which means a multifractal structure and highly intermittent, burst-like energy release regime. The absence of the necessary complexity in CH magnetic fields at scales above 2 Mm seems to be the most plausible reason why the net magnetic flux density does not seem to be related to the solar wind speed: the energy release dynamics, needed for solar wind acceleration, appears to occur at small scales below 1 Mm.