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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >How Do Auroral Substorms Depend on Earth's Dipole Magnetic Moment?
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How Do Auroral Substorms Depend on Earth's Dipole Magnetic Moment?

机译：极光亚暴取决于地球的偶极子吗磁矩吗?

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Earth's dipole magnetic moment M is known to decrease by ~9% over the past 150 years. It has been argued that the decrease in M makes the near-Earth space environment different. We investigated how the change in M affects the development of an auroral substorm by increasing and decreasing M by a factor of 1.5 in global magnetohydrodynamics simulation. The ionospheric conductivity decreases with increasing M, in accordance with the aid of empirical relations. When we imposed the southward interplanetary magnetic field, an auroral substorm took place regardless of M, but its development depends largely on M. When M is lower, (1) the expansion onset takes place later, (2) the auroral electrojet develops slowly, and (3) the maximum auroral electrojet increases. The first two consequences are probably associated with the slow magnetospheric convection as manifested by the polar cap potential drop. The third consequence is associated with the nonlinear dependence of substorm-associated field-aligned currents (FACs) on the ionospheric conductivity. The maximum values of the westward auroral electrojet and the net FACs increase with decreasing M, whereas the incident magnetic energy into the magnetosphere decreases with decreasing M. This implies that the efficiency of the generation of the substorm-associated FACs increases with decreasing M. It is also found that, for the lower M-value, the auroral oval shifts equatorward during the growth phase and expands more equatorward and poleward during the expansion phase. Evolution of substorms depends largely on the value of Earth's dipole moment and the ionospheric conductivity.
机译：地球的偶极子磁矩M是已知的减少~ 9%在过去的150年里。被认为M的减少使近地空间环境不同。米的变化如何影响调查极光亚暴的发展增加和减少M×1.5在全球的一个因素磁流体动力学模拟。电导率随增加M根据实证关系的援助。当我们向南星际磁场,极光亚暴不管M,但其发展所依赖在很大程度上M .当M较低,(1)扩张开始发生后,(2)极光电喷流发展缓慢,和(3)最大极光电喷流增加。后果可能是相关的缓慢的体现的磁性层的对流极冠潜在的下降。结果与非线性相关依赖的substorm-associated field-aligned电流在电离层电导率(流式细胞仪)。向西极光的最大值电喷流和净流式细胞仪增加降低M,而入射磁场能量进入磁层随降低m .这意味着效率substorm-associated流式细胞仪的生成增加而降低m也发现,对于m值越低,极光椭圆在成长阶段,朝赤道方向转变扩展更多的阻碍和向极扩张阶段。在很大程度上地球的偶极矩和的值电离层电导率。

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