Narrowing of the discrete auroral arc by the ionosphere
Narrowing of the discrete auroral arc by the ionosphere
复制标题
电离层使离散极光弧变窄
DOI：
10.1029/2007ja012402
复制
发表时间：
2007
影响因子：
--
通讯作者：
A. Streltsov
中科院分区：
文献类型：
--
作者：
A. Streltsov
[1] 我们研究了电离层在强烈、狭窄的离散极光弧发展中的作用。我们的研究表明，一对向下和向上的磁场排列电流（FAC）与电离层之间的相互作用可以导致向上电流通道变窄和向下电流通道变宽，使得初始电流对的总宽度保持不变。在这种情况下，向上电流的强度增加，而大范围向下电流的强度减小。促进向上和向下 FAC 之间这种不对称的条件包括低电离层电导率 (≤1 mho) 和中等强度的电流密度 (<5 μA/m 2 )。模拟表明，电离层不仅在电流的结构和幅度上造成显着的不对称，而且在相应的平行电场的结构和幅度上也造成显着的不对称。向上电流通道中的平行电场的动力学与电流本身的动力学类似，但向下电流通道中的场的动力学与电流的动力学不同。主要区别在于，向下电流通道的宽度随时间变宽，但通道内部平行电场的尺度变小。这种效应对于理解极光区的平行电子加速非常重要。特别是，它可以解释为什么所谓的“黑色”极光弧（由电离层沿着磁场线流动的电子产生）总是以非常窄的离散暗线的形式出现。
[1] We investigate the role of the ionosphere in the development of intense, narrow discrete auroral arcs. Our study shows that interactions between a pair of downward and upward magnetic field-aligned currents (FACs) and the ionosphere can lead to the narrowing of the upward current channel and broadening of the downward current channel such that the total width of the initial current pair remains the same. In this case the intensity of the upward current increases, and the intensity of the large-scale downward current decreases. Conditions promoting this asymmetry between the upward and downward FACs include low ionospheric conductivity (≤1 mho) and a moderate magnitude of the current density (<5 μA/m 2 ). Simulations show that the ionosphere causes significant asymmetry not only in the structure and amplitude of the currents but also in the structure and amplitude of the corresponding parallel electric fields. The dynamics of the parallel electric field in the upward current channel is similar to the dynamics of the current itself, but the dynamics of the field in the downward current channel differs from the dynamics of the current. The major difference is that the width of the downward current channel becomes broader with time but the scale size of the parallel electric field becomes smaller inside the channel. This effect is quite important for understanding the parallel electron acceleration in the auroral zone. In particular, it may explain why the so-called "black" auroral arcs, which are produced by the electrons flowing along the magnetic field lines from the ionosphere, always appear in the form of very narrow, discrete dark lines.
质子极光、强电场与电离层电子密度损耗之间的关系
DOI：
--
发表时间：
2009
期刊：
J. Geophys. Res. 114
影响因子：
--
作者：
Fujii;R.;Y. Iwata;S. Oyama;S. Nozawa;Y. Ogawa
通讯作者：
Y. Ogawa